133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen//===-- EarlyIfConversion.cpp - If-conversion on SSA form machine code ----===// 233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// 333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// The LLVM Compiler Infrastructure 433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// 533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// This file is distributed under the University of Illinois Open Source 633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// License. See LICENSE.TXT for details. 733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// 833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen//===----------------------------------------------------------------------===// 933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// 1033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// Early if-conversion is for out-of-order CPUs that don't have a lot of 1133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// predicable instructions. The goal is to eliminate conditional branches that 1233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// may mispredict. 1333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// 1433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// Instructions from both sides of the branch are executed specutatively, and a 1533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// cmov instruction selects the result. 1633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// 1733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen//===----------------------------------------------------------------------===// 1833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 1933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen#include "llvm/ADT/BitVector.h" 201f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen#include "llvm/ADT/PostOrderIterator.h" 2133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen#include "llvm/ADT/SetVector.h" 2233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen#include "llvm/ADT/SmallPtrSet.h" 2333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen#include "llvm/ADT/SparseSet.h" 24786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund Olesen#include "llvm/ADT/Statistic.h" 2533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen#include "llvm/CodeGen/MachineBranchProbabilityInfo.h" 261f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen#include "llvm/CodeGen/MachineDominators.h" 2733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen#include "llvm/CodeGen/MachineFunction.h" 2833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen#include "llvm/CodeGen/MachineFunctionPass.h" 2947730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen#include "llvm/CodeGen/MachineLoopInfo.h" 3033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen#include "llvm/CodeGen/MachineRegisterInfo.h" 315ed625c3cff2511469e9b3c5131c29fd89ddd482Jakob Stoklund Olesen#include "llvm/CodeGen/MachineTraceMetrics.h" 325ed625c3cff2511469e9b3c5131c29fd89ddd482Jakob Stoklund Olesen#include "llvm/CodeGen/Passes.h" 3333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen#include "llvm/Support/CommandLine.h" 3433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen#include "llvm/Support/Debug.h" 3533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen#include "llvm/Support/raw_ostream.h" 36d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/Target/TargetInstrInfo.h" 37d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/Target/TargetRegisterInfo.h" 38d04a8d4b33ff316ca4cf961e06c9e312eff8e64fChandler Carruth#include "llvm/Target/TargetSubtargetInfo.h" 3933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 4033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenusing namespace llvm; 4133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 42dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines#define DEBUG_TYPE "early-ifcvt" 43dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines 4433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// Absolute maximum number of instructions allowed per speculated block. 4533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// This bypasses all other heuristics, so it should be set fairly high. 4633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenstatic cl::opt<unsigned> 4733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund OlesenBlockInstrLimit("early-ifcvt-limit", cl::init(30), cl::Hidden, 4833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen cl::desc("Maximum number of instructions per speculated block.")); 4933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 5033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// Stress testing mode - disable heuristics. 5133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenstatic cl::opt<bool> Stress("stress-early-ifcvt", cl::Hidden, 5233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen cl::desc("Turn all knobs to 11")); 5333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 54786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund OlesenSTATISTIC(NumDiamondsSeen, "Number of diamonds"); 55786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund OlesenSTATISTIC(NumDiamondsConv, "Number of diamonds converted"); 56786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund OlesenSTATISTIC(NumTrianglesSeen, "Number of triangles"); 57786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund OlesenSTATISTIC(NumTrianglesConv, "Number of triangles converted"); 58786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund Olesen 5933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen//===----------------------------------------------------------------------===// 6033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// SSAIfConv 6133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen//===----------------------------------------------------------------------===// 6233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// 6333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// The SSAIfConv class performs if-conversion on SSA form machine code after 6400f43076a3d9cc76ef4736cf3e7215e19b05f6d5Matt Beaumont-Gay// determining if it is possible. The class contains no heuristics; external 6533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// code should be used to determine when if-conversion is a good idea. 6633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// 6700f43076a3d9cc76ef4736cf3e7215e19b05f6d5Matt Beaumont-Gay// SSAIfConv can convert both triangles and diamonds: 6833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// 6933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// Triangle: Head Diamond: Head 7000f43076a3d9cc76ef4736cf3e7215e19b05f6d5Matt Beaumont-Gay// | \ / \_ 7100f43076a3d9cc76ef4736cf3e7215e19b05f6d5Matt Beaumont-Gay// | \ / | 7233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// | [TF]BB FBB TBB 7333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// | / \ / 7433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// | / \ / 7533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// Tail Tail 7633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// 7733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// Instructions in the conditional blocks TBB and/or FBB are spliced into the 7800f43076a3d9cc76ef4736cf3e7215e19b05f6d5Matt Beaumont-Gay// Head block, and phis in the Tail block are converted to select instructions. 7933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// 8033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesennamespace { 8133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenclass SSAIfConv { 8233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen const TargetInstrInfo *TII; 8333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen const TargetRegisterInfo *TRI; 8433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineRegisterInfo *MRI; 8533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 861f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesenpublic: 8733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// The block containing the conditional branch. 8833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineBasicBlock *Head; 8933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 9033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// The block containing phis after the if-then-else. 9133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineBasicBlock *Tail; 9233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 9333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// The 'true' conditional block as determined by AnalyzeBranch. 9433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineBasicBlock *TBB; 9533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 9633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// The 'false' conditional block as determined by AnalyzeBranch. 9733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineBasicBlock *FBB; 9833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 9933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// isTriangle - When there is no 'else' block, either TBB or FBB will be 10033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// equal to Tail. 10133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen bool isTriangle() const { return TBB == Tail || FBB == Tail; } 10233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 103870da6de2c3f3f40360e04882b9ddf42ded0930aJakob Stoklund Olesen /// Returns the Tail predecessor for the True side. 104870da6de2c3f3f40360e04882b9ddf42ded0930aJakob Stoklund Olesen MachineBasicBlock *getTPred() const { return TBB == Tail ? Head : TBB; } 105870da6de2c3f3f40360e04882b9ddf42ded0930aJakob Stoklund Olesen 106870da6de2c3f3f40360e04882b9ddf42ded0930aJakob Stoklund Olesen /// Returns the Tail predecessor for the False side. 107870da6de2c3f3f40360e04882b9ddf42ded0930aJakob Stoklund Olesen MachineBasicBlock *getFPred() const { return FBB == Tail ? Head : FBB; } 108870da6de2c3f3f40360e04882b9ddf42ded0930aJakob Stoklund Olesen 10933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// Information about each phi in the Tail block. 11033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen struct PHIInfo { 11133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineInstr *PHI; 11233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen unsigned TReg, FReg; 11333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Latencies from Cond+Branch, TReg, and FReg to DstReg. 11433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen int CondCycles, TCycles, FCycles; 11533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 11633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen PHIInfo(MachineInstr *phi) 11733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen : PHI(phi), TReg(0), FReg(0), CondCycles(0), TCycles(0), FCycles(0) {} 11833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen }; 11933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 12033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen SmallVector<PHIInfo, 8> PHIs; 12133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 1221f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesenprivate: 1231f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen /// The branch condition determined by AnalyzeBranch. 1241f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen SmallVector<MachineOperand, 4> Cond; 1251f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen 12633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// Instructions in Head that define values used by the conditional blocks. 12733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// The hoisted instructions must be inserted after these instructions. 12833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen SmallPtrSet<MachineInstr*, 8> InsertAfter; 12933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 13033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// Register units clobbered by the conditional blocks. 13133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen BitVector ClobberedRegUnits; 13233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 13333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Scratch pad for findInsertionPoint. 13433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen SparseSet<unsigned> LiveRegUnits; 13533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 13633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// Insertion point in Head for speculatively executed instructions form TBB 13733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// and FBB. 13833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineBasicBlock::iterator InsertionPoint; 13933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 14033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// Return true if all non-terminator instructions in MBB can be safely 14133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// speculated. 14233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen bool canSpeculateInstrs(MachineBasicBlock *MBB); 14333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 14433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// Find a valid insertion point in Head. 14533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen bool findInsertionPoint(); 14633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 147bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen /// Replace PHI instructions in Tail with selects. 148bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen void replacePHIInstrs(); 149bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen 150bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen /// Insert selects and rewrite PHI operands to use them. 151bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen void rewritePHIOperands(); 152bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen 15333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenpublic: 15433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// runOnMachineFunction - Initialize per-function data structures. 15533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen void runOnMachineFunction(MachineFunction &MF) { 15633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen TII = MF.getTarget().getInstrInfo(); 15733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen TRI = MF.getTarget().getRegisterInfo(); 15833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MRI = &MF.getRegInfo(); 15933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen LiveRegUnits.clear(); 16033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen LiveRegUnits.setUniverse(TRI->getNumRegUnits()); 16133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen ClobberedRegUnits.clear(); 16233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen ClobberedRegUnits.resize(TRI->getNumRegUnits()); 16333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 16433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 16533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// canConvertIf - If the sub-CFG headed by MBB can be if-converted, 16633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// initialize the internal state, and return true. 16733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen bool canConvertIf(MachineBasicBlock *MBB); 16833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 16933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen /// convertIf - If-convert the last block passed to canConvertIf(), assuming 1701f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen /// it is possible. Add any erased blocks to RemovedBlocks. 1711f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen void convertIf(SmallVectorImpl<MachineBasicBlock*> &RemovedBlocks); 17233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen}; 17333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen} // end anonymous namespace 17433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 17533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 17633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// canSpeculateInstrs - Returns true if all the instructions in MBB can safely 17733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// be speculated. The terminators are not considered. 17833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// 17933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// If instructions use any values that are defined in the head basic block, 18033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// the defining instructions are added to InsertAfter. 18133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// 18233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// Any clobbered regunits are added to ClobberedRegUnits. 18333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// 18433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenbool SSAIfConv::canSpeculateInstrs(MachineBasicBlock *MBB) { 18533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Reject any live-in physregs. It's probably CPSR/EFLAGS, and very hard to 18633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // get right. 18733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (!MBB->livein_empty()) { 18833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "BB#" << MBB->getNumber() << " has live-ins.\n"); 18933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 19033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 19133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 19233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen unsigned InstrCount = 0; 19386fc3100b552c8d400160581c2a00f2fd7b83b45Jakob Stoklund Olesen 19486fc3100b552c8d400160581c2a00f2fd7b83b45Jakob Stoklund Olesen // Check all instructions, except the terminators. It is assumed that 19586fc3100b552c8d400160581c2a00f2fd7b83b45Jakob Stoklund Olesen // terminators never have side effects or define any used register values. 19633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen for (MachineBasicBlock::iterator I = MBB->begin(), 19733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen E = MBB->getFirstTerminator(); I != E; ++I) { 19833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (I->isDebugValue()) 19933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen continue; 20033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 20133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (++InstrCount > BlockInstrLimit && !Stress) { 20233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "BB#" << MBB->getNumber() << " has more than " 20333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen << BlockInstrLimit << " instructions.\n"); 20433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 20533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 20633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 20733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // There shouldn't normally be any phis in a single-predecessor block. 20833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (I->isPHI()) { 20933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "Can't hoist: " << *I); 21033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 21133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 21233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 21333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Don't speculate loads. Note that it may be possible and desirable to 21433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // speculate GOT or constant pool loads that are guaranteed not to trap, 21533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // but we don't support that for now. 21633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (I->mayLoad()) { 21733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "Won't speculate load: " << *I); 21833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 21933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 22033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 22133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // We never speculate stores, so an AA pointer isn't necessary. 22233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen bool DontMoveAcrossStore = true; 223dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines if (!I->isSafeToMove(TII, nullptr, DontMoveAcrossStore)) { 22433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "Can't speculate: " << *I); 22533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 22633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 22733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 22833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Check for any dependencies on Head instructions. 22933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen for (MIOperands MO(I); MO.isValid(); ++MO) { 23033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (MO->isRegMask()) { 23133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "Won't speculate regmask: " << *I); 23233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 23333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 23433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (!MO->isReg()) 23533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen continue; 23633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen unsigned Reg = MO->getReg(); 23733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 23833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Remember clobbered regunits. 23933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (MO->isDef() && TargetRegisterInfo::isPhysicalRegister(Reg)) 24033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen for (MCRegUnitIterator Units(Reg, TRI); Units.isValid(); ++Units) 24133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen ClobberedRegUnits.set(*Units); 24233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 24333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (!MO->readsReg() || !TargetRegisterInfo::isVirtualRegister(Reg)) 24433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen continue; 24533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineInstr *DefMI = MRI->getVRegDef(Reg); 24633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (!DefMI || DefMI->getParent() != Head) 24733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen continue; 24833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (InsertAfter.insert(DefMI)) 24933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "BB#" << MBB->getNumber() << " depends on " << *DefMI); 25033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (DefMI->isTerminator()) { 25133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "Can't insert instructions below terminator.\n"); 25233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 25333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 25433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 25533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 25633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return true; 25733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen} 25833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 25933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 26033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// Find an insertion point in Head for the speculated instructions. The 26133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// insertion point must be: 26233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// 26333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// 1. Before any terminators. 26433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// 2. After any instructions in InsertAfter. 26533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// 3. Not have any clobbered regunits live. 26633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// 26733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// This function sets InsertionPoint and returns true when successful, it 26833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// returns false if no valid insertion point could be found. 26933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// 27033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenbool SSAIfConv::findInsertionPoint() { 27133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Keep track of live regunits before the current position. 27233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Only track RegUnits that are also in ClobberedRegUnits. 27333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen LiveRegUnits.clear(); 27433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen SmallVector<unsigned, 8> Reads; 27533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineBasicBlock::iterator FirstTerm = Head->getFirstTerminator(); 27633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineBasicBlock::iterator I = Head->end(); 27733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineBasicBlock::iterator B = Head->begin(); 27833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen while (I != B) { 27933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen --I; 28033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Some of the conditional code depends in I. 28133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (InsertAfter.count(I)) { 28233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "Can't insert code after " << *I); 28333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 28433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 28533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 28633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Update live regunits. 28733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen for (MIOperands MO(I); MO.isValid(); ++MO) { 28833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // We're ignoring regmask operands. That is conservatively correct. 28933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (!MO->isReg()) 29033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen continue; 29133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen unsigned Reg = MO->getReg(); 29233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (!TargetRegisterInfo::isPhysicalRegister(Reg)) 29333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen continue; 29433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // I clobbers Reg, so it isn't live before I. 29533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (MO->isDef()) 29633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen for (MCRegUnitIterator Units(Reg, TRI); Units.isValid(); ++Units) 29733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen LiveRegUnits.erase(*Units); 29833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Unless I reads Reg. 29933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (MO->readsReg()) 30033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen Reads.push_back(Reg); 30133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 30233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Anything read by I is live before I. 30333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen while (!Reads.empty()) 30433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen for (MCRegUnitIterator Units(Reads.pop_back_val(), TRI); Units.isValid(); 30533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen ++Units) 30633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (ClobberedRegUnits.test(*Units)) 30733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen LiveRegUnits.insert(*Units); 30833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 30933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // We can't insert before a terminator. 31033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (I != FirstTerm && I->isTerminator()) 31133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen continue; 31233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 31333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Some of the clobbered registers are live before I, not a valid insertion 31433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // point. 31533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (!LiveRegUnits.empty()) { 31633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG({ 31733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen dbgs() << "Would clobber"; 31833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen for (SparseSet<unsigned>::const_iterator 31933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen i = LiveRegUnits.begin(), e = LiveRegUnits.end(); i != e; ++i) 32033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen dbgs() << ' ' << PrintRegUnit(*i, TRI); 32133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen dbgs() << " live before " << *I; 32233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen }); 32333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen continue; 32433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 32533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 32633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // This is a valid insertion point. 32733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen InsertionPoint = I; 32833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "Can insert before " << *I); 32933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return true; 33033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 33133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "No legal insertion point found.\n"); 33233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 33333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen} 33433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 33533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 33633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 33733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// canConvertIf - analyze the sub-cfg rooted in MBB, and return true if it is 33833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// a potential candidate for if-conversion. Fill out the internal state. 33933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// 34033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenbool SSAIfConv::canConvertIf(MachineBasicBlock *MBB) { 34133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen Head = MBB; 342dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines TBB = FBB = Tail = nullptr; 34333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 34433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (Head->succ_size() != 2) 34533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 34633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineBasicBlock *Succ0 = Head->succ_begin()[0]; 34733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineBasicBlock *Succ1 = Head->succ_begin()[1]; 34833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 34933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Canonicalize so Succ0 has MBB as its single predecessor. 35033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (Succ0->pred_size() != 1) 35133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen std::swap(Succ0, Succ1); 35233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 35333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (Succ0->pred_size() != 1 || Succ0->succ_size() != 1) 35433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 35533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 35633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen Tail = Succ0->succ_begin()[0]; 35733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 35833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // This is not a triangle. 35933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (Tail != Succ1) { 36033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Check for a diamond. We won't deal with any critical edges. 36133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (Succ1->pred_size() != 1 || Succ1->succ_size() != 1 || 36233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen Succ1->succ_begin()[0] != Tail) 36333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 36433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "\nDiamond: BB#" << Head->getNumber() 36533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen << " -> BB#" << Succ0->getNumber() 36633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen << "/BB#" << Succ1->getNumber() 36733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen << " -> BB#" << Tail->getNumber() << '\n'); 36833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 36933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Live-in physregs are tricky to get right when speculating code. 37033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (!Tail->livein_empty()) { 37133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "Tail has live-ins.\n"); 37233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 37333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 37433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } else { 37533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "\nTriangle: BB#" << Head->getNumber() 37633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen << " -> BB#" << Succ0->getNumber() 37733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen << " -> BB#" << Tail->getNumber() << '\n'); 37833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 37933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 38033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // This is a triangle or a diamond. 38133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // If Tail doesn't have any phis, there must be side effects. 38233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (Tail->empty() || !Tail->front().isPHI()) { 38333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "No phis in tail.\n"); 38433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 38533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 38633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 38733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // The branch we're looking to eliminate must be analyzable. 38833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen Cond.clear(); 38933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (TII->AnalyzeBranch(*Head, TBB, FBB, Cond)) { 39033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "Branch not analyzable.\n"); 39133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 39233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 39333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 39433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // This is weird, probably some sort of degenerate CFG. 39533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (!TBB) { 39633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "AnalyzeBranch didn't find conditional branch.\n"); 39733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 39833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 39933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 40033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // AnalyzeBranch doesn't set FBB on a fall-through branch. 40133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Make sure it is always set. 40233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen FBB = TBB == Succ0 ? Succ1 : Succ0; 40333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 40433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Any phis in the tail block must be convertible to selects. 40533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen PHIs.clear(); 406870da6de2c3f3f40360e04882b9ddf42ded0930aJakob Stoklund Olesen MachineBasicBlock *TPred = getTPred(); 407870da6de2c3f3f40360e04882b9ddf42ded0930aJakob Stoklund Olesen MachineBasicBlock *FPred = getFPred(); 40833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen for (MachineBasicBlock::iterator I = Tail->begin(), E = Tail->end(); 40933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen I != E && I->isPHI(); ++I) { 41033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen PHIs.push_back(&*I); 41133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen PHIInfo &PI = PHIs.back(); 41233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Find PHI operands corresponding to TPred and FPred. 41333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen for (unsigned i = 1; i != PI.PHI->getNumOperands(); i += 2) { 41433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (PI.PHI->getOperand(i+1).getMBB() == TPred) 41533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen PI.TReg = PI.PHI->getOperand(i).getReg(); 41633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (PI.PHI->getOperand(i+1).getMBB() == FPred) 41733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen PI.FReg = PI.PHI->getOperand(i).getReg(); 41833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 41933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen assert(TargetRegisterInfo::isVirtualRegister(PI.TReg) && "Bad PHI"); 42033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen assert(TargetRegisterInfo::isVirtualRegister(PI.FReg) && "Bad PHI"); 42133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 42233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Get target information. 42333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (!TII->canInsertSelect(*Head, Cond, PI.TReg, PI.FReg, 42433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen PI.CondCycles, PI.TCycles, PI.FCycles)) { 42533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "Can't convert: " << *PI.PHI); 42633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 42733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 42833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 42933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 43033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Check that the conditional instructions can be speculated. 43133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen InsertAfter.clear(); 43233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen ClobberedRegUnits.reset(); 43333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (TBB != Tail && !canSpeculateInstrs(TBB)) 43433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 43533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (FBB != Tail && !canSpeculateInstrs(FBB)) 43633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 43733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 43833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Try to find a valid insertion point for the speculated instructions in the 43933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // head basic block. 44033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (!findInsertionPoint()) 44133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return false; 44233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 443786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund Olesen if (isTriangle()) 444786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund Olesen ++NumTrianglesSeen; 445786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund Olesen else 446786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund Olesen ++NumDiamondsSeen; 44733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return true; 44833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen} 44933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 450bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen/// replacePHIInstrs - Completely replace PHI instructions with selects. 451bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen/// This is possible when the only Tail predecessors are the if-converted 452bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen/// blocks. 453bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesenvoid SSAIfConv::replacePHIInstrs() { 454bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen assert(Tail->pred_size() == 2 && "Cannot replace PHIs"); 45533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineBasicBlock::iterator FirstTerm = Head->getFirstTerminator(); 45633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen assert(FirstTerm != Head->end() && "No terminators"); 45733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DebugLoc HeadDL = FirstTerm->getDebugLoc(); 45833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 45933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Convert all PHIs to select instructions inserted before FirstTerm. 46033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen for (unsigned i = 0, e = PHIs.size(); i != e; ++i) { 46133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen PHIInfo &PI = PHIs[i]; 46233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "If-converting " << *PI.PHI); 46333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen unsigned DstReg = PI.PHI->getOperand(0).getReg(); 46433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen TII->insertSelect(*Head, FirstTerm, HeadDL, DstReg, Cond, PI.TReg, PI.FReg); 46536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines DEBUG(dbgs() << " --> " << *std::prev(FirstTerm)); 46633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen PI.PHI->eraseFromParent(); 467dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines PI.PHI = nullptr; 46833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 469bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen} 470bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen 471bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen/// rewritePHIOperands - When there are additional Tail predecessors, insert 472bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen/// select instructions in Head and rewrite PHI operands to use the selects. 473bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen/// Keep the PHI instructions in Tail to handle the other predecessors. 474bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesenvoid SSAIfConv::rewritePHIOperands() { 475bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen MachineBasicBlock::iterator FirstTerm = Head->getFirstTerminator(); 476bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen assert(FirstTerm != Head->end() && "No terminators"); 477bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen DebugLoc HeadDL = FirstTerm->getDebugLoc(); 478bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen 479bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen // Convert all PHIs to select instructions inserted before FirstTerm. 480bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen for (unsigned i = 0, e = PHIs.size(); i != e; ++i) { 481bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen PHIInfo &PI = PHIs[i]; 482bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen DEBUG(dbgs() << "If-converting " << *PI.PHI); 483bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen unsigned PHIDst = PI.PHI->getOperand(0).getReg(); 484bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen unsigned DstReg = MRI->createVirtualRegister(MRI->getRegClass(PHIDst)); 485bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen TII->insertSelect(*Head, FirstTerm, HeadDL, DstReg, Cond, PI.TReg, PI.FReg); 48636b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines DEBUG(dbgs() << " --> " << *std::prev(FirstTerm)); 487bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen 488bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen // Rewrite PHI operands TPred -> (DstReg, Head), remove FPred. 489bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen for (unsigned i = PI.PHI->getNumOperands(); i != 1; i -= 2) { 490bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen MachineBasicBlock *MBB = PI.PHI->getOperand(i-1).getMBB(); 491bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen if (MBB == getTPred()) { 492bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen PI.PHI->getOperand(i-1).setMBB(Head); 493bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen PI.PHI->getOperand(i-2).setReg(DstReg); 494bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen } else if (MBB == getFPred()) { 495bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen PI.PHI->RemoveOperand(i-1); 496bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen PI.PHI->RemoveOperand(i-2); 497bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen } 498bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen } 499bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen DEBUG(dbgs() << " --> " << *PI.PHI); 500bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen } 501bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen} 502bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen 503bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen/// convertIf - Execute the if conversion after canConvertIf has determined the 504bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen/// feasibility. 505bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen/// 506bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen/// Any basic blocks erased will be added to RemovedBlocks. 507bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen/// 508bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesenvoid SSAIfConv::convertIf(SmallVectorImpl<MachineBasicBlock*> &RemovedBlocks) { 509bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen assert(Head && Tail && TBB && FBB && "Call canConvertIf first."); 510bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen 511786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund Olesen // Update statistics. 512786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund Olesen if (isTriangle()) 513786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund Olesen ++NumTrianglesConv; 514786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund Olesen else 515786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund Olesen ++NumDiamondsConv; 516786556c26847befdb011298fd7b36ae86fd150b0Jakob Stoklund Olesen 517bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen // Move all instructions into Head, except for the terminators. 518bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen if (TBB != Tail) 519bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen Head->splice(InsertionPoint, TBB, TBB->begin(), TBB->getFirstTerminator()); 520bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen if (FBB != Tail) 521bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen Head->splice(InsertionPoint, FBB, FBB->begin(), FBB->getFirstTerminator()); 522bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen 523bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen // Are there extra Tail predecessors? 524bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen bool ExtraPreds = Tail->pred_size() != 2; 525bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen if (ExtraPreds) 526bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen rewritePHIOperands(); 527bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen else 528bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen replacePHIInstrs(); 52933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 53033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Fix up the CFG, temporarily leave Head without any successors. 53133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen Head->removeSuccessor(TBB); 53233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen Head->removeSuccessor(FBB); 53333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (TBB != Tail) 53433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen TBB->removeSuccessor(Tail); 53533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen if (FBB != Tail) 53633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen FBB->removeSuccessor(Tail); 53733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 53833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Fix up Head's terminators. 53933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // It should become a single branch or a fallthrough. 540bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen DebugLoc HeadDL = Head->getFirstTerminator()->getDebugLoc(); 54133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen TII->RemoveBranch(*Head); 54233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 54333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Erase the now empty conditional blocks. It is likely that Head can fall 54433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // through to Tail, and we can join the two blocks. 5451f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen if (TBB != Tail) { 5461f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen RemovedBlocks.push_back(TBB); 5471f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen TBB->eraseFromParent(); 5481f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen } 5491f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen if (FBB != Tail) { 5501f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen RemovedBlocks.push_back(FBB); 5511f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen FBB->eraseFromParent(); 5521f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen } 55333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 55433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen assert(Head->succ_empty() && "Additional head successors?"); 555bc70ff3cb977fd69e120d89b0e04f316d87cdbefJakob Stoklund Olesen if (!ExtraPreds && Head->isLayoutSuccessor(Tail)) { 55633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // Splice Tail onto the end of Head. 55733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "Joining tail BB#" << Tail->getNumber() 55833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen << " into head BB#" << Head->getNumber() << '\n'); 55933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen Head->splice(Head->end(), Tail, 56033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen Tail->begin(), Tail->end()); 56133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen Head->transferSuccessorsAndUpdatePHIs(Tail); 5621f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen RemovedBlocks.push_back(Tail); 5631f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen Tail->eraseFromParent(); 56433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } else { 56533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen // We need a branch to Tail, let code placement work it out later. 56633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "Converting to unconditional branch.\n"); 56733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen SmallVector<MachineOperand, 0> EmptyCond; 568dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines TII->InsertBranch(*Head, Tail, nullptr, EmptyCond, HeadDL); 56933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen Head->addSuccessor(Tail); 57033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen } 57133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << *Head); 57233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen} 57333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 57433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 57533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen//===----------------------------------------------------------------------===// 57633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen// EarlyIfConverter Pass 57733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen//===----------------------------------------------------------------------===// 57833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 57933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesennamespace { 58033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenclass EarlyIfConverter : public MachineFunctionPass { 58133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen const TargetInstrInfo *TII; 58233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen const TargetRegisterInfo *TRI; 5830fac6aa076450f5474feb2ec697b7d63d33fa567Jakob Stoklund Olesen const MCSchedModel *SchedModel; 58433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineRegisterInfo *MRI; 5851f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen MachineDominatorTree *DomTree; 58647730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen MachineLoopInfo *Loops; 5879f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen MachineTraceMetrics *Traces; 5889f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen MachineTraceMetrics::Ensemble *MinInstr; 58933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen SSAIfConv IfConv; 59033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 59133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenpublic: 59233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen static char ID; 59333242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen EarlyIfConverter() : MachineFunctionPass(ID) {} 59436b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines void getAnalysisUsage(AnalysisUsage &AU) const override; 59536b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines bool runOnMachineFunction(MachineFunction &MF) override; 59636b56886974eae4f9c5ebc96befd3e7bfe5de338Stephen Hines const char *getPassName() const override { return "Early If-Conversion"; } 59733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 59833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenprivate: 59933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen bool tryConvertIf(MachineBasicBlock*); 6001f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen void updateDomTree(ArrayRef<MachineBasicBlock*> Removed); 60147730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen void updateLoops(ArrayRef<MachineBasicBlock*> Removed); 6029f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen void invalidateTraces(); 6039f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen bool shouldConvertIf(); 60433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen}; 60533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen} // end anonymous namespace 60633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 60733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenchar EarlyIfConverter::ID = 0; 60833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenchar &llvm::EarlyIfConverterID = EarlyIfConverter::ID; 60933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 61033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund OlesenINITIALIZE_PASS_BEGIN(EarlyIfConverter, 61133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen "early-ifcvt", "Early If Converter", false, false) 61233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund OlesenINITIALIZE_PASS_DEPENDENCY(MachineBranchProbabilityInfo) 6131f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund OlesenINITIALIZE_PASS_DEPENDENCY(MachineDominatorTree) 6149f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund OlesenINITIALIZE_PASS_DEPENDENCY(MachineTraceMetrics) 61533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund OlesenINITIALIZE_PASS_END(EarlyIfConverter, 61633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen "early-ifcvt", "Early If Converter", false, false) 61733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 61833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenvoid EarlyIfConverter::getAnalysisUsage(AnalysisUsage &AU) const { 61933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen AU.addRequired<MachineBranchProbabilityInfo>(); 6201f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen AU.addRequired<MachineDominatorTree>(); 6211f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen AU.addPreserved<MachineDominatorTree>(); 62247730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen AU.addRequired<MachineLoopInfo>(); 62347730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen AU.addPreserved<MachineLoopInfo>(); 6249f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen AU.addRequired<MachineTraceMetrics>(); 6259f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen AU.addPreserved<MachineTraceMetrics>(); 62633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MachineFunctionPass::getAnalysisUsage(AU); 62733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen} 62833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 6291f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen/// Update the dominator tree after if-conversion erased some blocks. 6301f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesenvoid EarlyIfConverter::updateDomTree(ArrayRef<MachineBasicBlock*> Removed) { 6311f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen // convertIf can remove TBB, FBB, and Tail can be merged into Head. 6321f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen // TBB and FBB should not dominate any blocks. 6331f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen // Tail children should be transferred to Head. 6341f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen MachineDomTreeNode *HeadNode = DomTree->getNode(IfConv.Head); 6351f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen for (unsigned i = 0, e = Removed.size(); i != e; ++i) { 6361f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen MachineDomTreeNode *Node = DomTree->getNode(Removed[i]); 6371f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen assert(Node != HeadNode && "Cannot erase the head node"); 6381f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen while (Node->getNumChildren()) { 6391f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen assert(Node->getBlock() == IfConv.Tail && "Unexpected children"); 6401f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen DomTree->changeImmediateDominator(Node->getChildren().back(), HeadNode); 6411f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen } 6421f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen DomTree->eraseNode(Removed[i]); 6431f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen } 6441f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen} 6451f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen 64647730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen/// Update LoopInfo after if-conversion. 64747730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesenvoid EarlyIfConverter::updateLoops(ArrayRef<MachineBasicBlock*> Removed) { 64847730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen if (!Loops) 64947730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen return; 65047730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen // If-conversion doesn't change loop structure, and it doesn't mess with back 65147730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen // edges, so updating LoopInfo is simply removing the dead blocks. 65247730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen for (unsigned i = 0, e = Removed.size(); i != e; ++i) 65347730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen Loops->removeBlock(Removed[i]); 65447730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen} 65547730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen 6569f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen/// Invalidate MachineTraceMetrics before if-conversion. 6579f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesenvoid EarlyIfConverter::invalidateTraces() { 658ef6c76c984f821ea866902a7f9e695b16e971468Jakob Stoklund Olesen Traces->verifyAnalysis(); 6599f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen Traces->invalidate(IfConv.Head); 6609f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen Traces->invalidate(IfConv.Tail); 6619f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen Traces->invalidate(IfConv.TBB); 6629f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen Traces->invalidate(IfConv.FBB); 663ef6c76c984f821ea866902a7f9e695b16e971468Jakob Stoklund Olesen Traces->verifyAnalysis(); 6649f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen} 6659f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen 666eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen// Adjust cycles with downward saturation. 667eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesenstatic unsigned adjCycles(unsigned Cyc, int Delta) { 668eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen if (Delta < 0 && Cyc + Delta > Cyc) 669eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen return 0; 670eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen return Cyc + Delta; 671eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen} 672eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen 6739f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen/// Apply cost model and heuristics to the if-conversion in IfConv. 6749f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen/// Return true if the conversion is a good idea. 6759f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen/// 6769f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesenbool EarlyIfConverter::shouldConvertIf() { 677d6cf5f4224d0e600ebb810f1da09aabaeea7e6f3Jakob Stoklund Olesen // Stress testing mode disables all cost considerations. 678d6cf5f4224d0e600ebb810f1da09aabaeea7e6f3Jakob Stoklund Olesen if (Stress) 679d6cf5f4224d0e600ebb810f1da09aabaeea7e6f3Jakob Stoklund Olesen return true; 680d6cf5f4224d0e600ebb810f1da09aabaeea7e6f3Jakob Stoklund Olesen 6819f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen if (!MinInstr) 6829f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen MinInstr = Traces->getEnsemble(MachineTraceMetrics::TS_MinInstrCount); 68384ef6ba44394f983d985b02e328cbb2dd779e4b0Jakob Stoklund Olesen 684eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen MachineTraceMetrics::Trace TBBTrace = MinInstr->getTrace(IfConv.getTPred()); 685eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen MachineTraceMetrics::Trace FBBTrace = MinInstr->getTrace(IfConv.getFPred()); 68684ef6ba44394f983d985b02e328cbb2dd779e4b0Jakob Stoklund Olesen DEBUG(dbgs() << "TBB: " << TBBTrace << "FBB: " << FBBTrace); 687eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen unsigned MinCrit = std::min(TBBTrace.getCriticalPath(), 688eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen FBBTrace.getCriticalPath()); 689eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen 690eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen // Set a somewhat arbitrary limit on the critical path extension we accept. 691eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen unsigned CritLimit = SchedModel->MispredictPenalty/2; 692eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen 693eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen // If-conversion only makes sense when there is unexploited ILP. Compute the 694eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen // maximum-ILP resource length of the trace after if-conversion. Compare it 695eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen // to the shortest critical path. 696eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen SmallVector<const MachineBasicBlock*, 1> ExtraBlocks; 697eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen if (IfConv.TBB != IfConv.Tail) 698eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen ExtraBlocks.push_back(IfConv.TBB); 699eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen unsigned ResLength = FBBTrace.getResourceLength(ExtraBlocks); 700eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen DEBUG(dbgs() << "Resource length " << ResLength 701eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen << ", minimal critical path " << MinCrit << '\n'); 702eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen if (ResLength > MinCrit + CritLimit) { 703eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen DEBUG(dbgs() << "Not enough available ILP.\n"); 70484ef6ba44394f983d985b02e328cbb2dd779e4b0Jakob Stoklund Olesen return false; 70584ef6ba44394f983d985b02e328cbb2dd779e4b0Jakob Stoklund Olesen } 706eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen 707eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen // Assume that the depth of the first head terminator will also be the depth 708eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen // of the select instruction inserted, as determined by the flag dependency. 709eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen // TBB / FBB data dependencies may delay the select even more. 710eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen MachineTraceMetrics::Trace HeadTrace = MinInstr->getTrace(IfConv.Head); 711eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen unsigned BranchDepth = 712eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen HeadTrace.getInstrCycles(IfConv.Head->getFirstTerminator()).Depth; 713eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen DEBUG(dbgs() << "Branch depth: " << BranchDepth << '\n'); 714eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen 715eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen // Look at all the tail phis, and compute the critical path extension caused 716eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen // by inserting select instructions. 717eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen MachineTraceMetrics::Trace TailTrace = MinInstr->getTrace(IfConv.Tail); 718eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen for (unsigned i = 0, e = IfConv.PHIs.size(); i != e; ++i) { 719eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen SSAIfConv::PHIInfo &PI = IfConv.PHIs[i]; 720eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen unsigned Slack = TailTrace.getInstrSlack(PI.PHI); 721eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen unsigned MaxDepth = Slack + TailTrace.getInstrCycles(PI.PHI).Depth; 722eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen DEBUG(dbgs() << "Slack " << Slack << ":\t" << *PI.PHI); 723eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen 724eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen // The condition is pulled into the critical path. 725eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen unsigned CondDepth = adjCycles(BranchDepth, PI.CondCycles); 726eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen if (CondDepth > MaxDepth) { 727eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen unsigned Extra = CondDepth - MaxDepth; 728eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen DEBUG(dbgs() << "Condition adds " << Extra << " cycles.\n"); 729eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen if (Extra > CritLimit) { 730eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen DEBUG(dbgs() << "Exceeds limit of " << CritLimit << '\n'); 731eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen return false; 732eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen } 733eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen } 734eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen 735eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen // The TBB value is pulled into the critical path. 736eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen unsigned TDepth = adjCycles(TBBTrace.getPHIDepth(PI.PHI), PI.TCycles); 737eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen if (TDepth > MaxDepth) { 738eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen unsigned Extra = TDepth - MaxDepth; 739eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen DEBUG(dbgs() << "TBB data adds " << Extra << " cycles.\n"); 740eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen if (Extra > CritLimit) { 741eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen DEBUG(dbgs() << "Exceeds limit of " << CritLimit << '\n'); 742eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen return false; 743eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen } 744eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen } 745eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen 746eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen // The FBB value is pulled into the critical path. 747eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen unsigned FDepth = adjCycles(FBBTrace.getPHIDepth(PI.PHI), PI.FCycles); 748eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen if (FDepth > MaxDepth) { 749eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen unsigned Extra = FDepth - MaxDepth; 750eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen DEBUG(dbgs() << "FBB data adds " << Extra << " cycles.\n"); 751eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen if (Extra > CritLimit) { 752eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen DEBUG(dbgs() << "Exceeds limit of " << CritLimit << '\n'); 753eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen return false; 754eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen } 755eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen } 756eb74c08192d9c9425b2d8cf08852e9e787a87881Jakob Stoklund Olesen } 7579f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen return true; 7589f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen} 7599f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen 76033242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// Attempt repeated if-conversion on MBB, return true if successful. 76133242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen/// 76233242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenbool EarlyIfConverter::tryConvertIf(MachineBasicBlock *MBB) { 7631f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen bool Changed = false; 7649f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen while (IfConv.canConvertIf(MBB) && shouldConvertIf()) { 7651f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen // If-convert MBB and update analyses. 7669f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen invalidateTraces(); 7671f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen SmallVector<MachineBasicBlock*, 4> RemovedBlocks; 7681f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen IfConv.convertIf(RemovedBlocks); 7691f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen Changed = true; 7701f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen updateDomTree(RemovedBlocks); 77147730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen updateLoops(RemovedBlocks); 7721f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen } 7731f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen return Changed; 77433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen} 77533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 77633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesenbool EarlyIfConverter::runOnMachineFunction(MachineFunction &MF) { 77733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen DEBUG(dbgs() << "********** EARLY IF-CONVERSION **********\n" 778986d76d7b3844b9a2f3d01a48975952749267a93David Blaikie << "********** Function: " << MF.getName() << '\n'); 779dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines // Only run if conversion if the target wants it. 780dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines if (!MF.getTarget() 781dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines .getSubtarget<TargetSubtargetInfo>() 782dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines .enableEarlyIfConversion()) 783dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines return false; 784dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines 78533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen TII = MF.getTarget().getInstrInfo(); 78633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen TRI = MF.getTarget().getRegisterInfo(); 787e6521b57cc475e3606fd90e48363cc27aa17cc80Jakob Stoklund Olesen SchedModel = 788e6521b57cc475e3606fd90e48363cc27aa17cc80Jakob Stoklund Olesen MF.getTarget().getSubtarget<TargetSubtargetInfo>().getSchedModel(); 78933242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen MRI = &MF.getRegInfo(); 7901f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen DomTree = &getAnalysis<MachineDominatorTree>(); 79147730a774dd6392744ee62c7385665c780e1c4e1Jakob Stoklund Olesen Loops = getAnalysisIfAvailable<MachineLoopInfo>(); 7929f63e104271eb91e545fa8cdb16fb9e10a8a9578Jakob Stoklund Olesen Traces = &getAnalysis<MachineTraceMetrics>(); 793dce4a407a24b04eebc6a376f8e62b41aaa7b071fStephen Hines MinInstr = nullptr; 79433242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 79533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen bool Changed = false; 79633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen IfConv.runOnMachineFunction(MF); 79733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 7981f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen // Visit blocks in dominator tree post-order. The post-order enables nested 7991f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen // if-conversion in a single pass. The tryConvertIf() function may erase 8001f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen // blocks, but only blocks dominated by the head block. This makes it safe to 8011f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen // update the dominator tree while the post-order iterator is still active. 8021f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen for (po_iterator<MachineDominatorTree*> 8031f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen I = po_begin(DomTree), E = po_end(DomTree); I != E; ++I) 8041f523dc45e29874bf8101e50b42ba707ffc8aff9Jakob Stoklund Olesen if (tryConvertIf(I->getBlock())) 80533242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen Changed = true; 80633242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen 80733242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen return Changed; 80833242fd3ed5586091e73254b58dd1825e9d53c60Jakob Stoklund Olesen} 809