17cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 27cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak//==- MachineBranchProbabilityInfo.h - Machine Branch Probability Analysis -==// 37cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// 47cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// The LLVM Compiler Infrastructure 57cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// 67cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// This file is distributed under the University of Illinois Open Source 77cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// License. See LICENSE.TXT for details. 87cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// 97cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak//===----------------------------------------------------------------------===// 107cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// 117cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// This pass is used to evaluate branch probabilties on machine basic blocks. 127cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak// 137cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak//===----------------------------------------------------------------------===// 147cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 157cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak#ifndef LLVM_CODEGEN_MACHINEBRANCHPROBABILITYINFO_H 167cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak#define LLVM_CODEGEN_MACHINEBRANCHPROBABILITYINFO_H 177cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 18990ca5517fd6666d4049b6b8281d9df99da11637Jakob Stoklund Olesen#include "llvm/CodeGen/MachineBasicBlock.h" 19255f89faee13dc491cb64fbeae3c763e7e2ea4e6Chandler Carruth#include "llvm/Pass.h" 207cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak#include "llvm/Support/BranchProbability.h" 217cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak#include <climits> 227cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 237cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszaknamespace llvm { 247cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 257cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszakclass MachineBranchProbabilityInfo : public ImmutablePass { 262d24e2a396a1d211baaeedf32148a3b657240170David Blaikie virtual void anchor(); 277cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 287cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // Default weight value. Used when we don't have information about the edge. 297cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // TODO: DEFAULT_WEIGHT makes sense during static predication, when none of 307cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // the successors have a weight yet. But it doesn't make sense when providing 317cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // weight to an edge that may have siblings with non-zero weights. This can 327cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // be handled various ways, but it's probably fine for an edge with unknown 337cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // weight to just "inherit" the non-zero weight of an adjacent successor. 347cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak static const uint32_t DEFAULT_WEIGHT = 16; 357cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 367cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszakpublic: 377cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak static char ID; 387cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 397cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak MachineBranchProbabilityInfo() : ImmutablePass(ID) { 407cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak PassRegistry &Registry = *PassRegistry::getPassRegistry(); 417cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak initializeMachineBranchProbabilityInfoPass(Registry); 427cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak } 437cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 447cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak void getAnalysisUsage(AnalysisUsage &AU) const { 457cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak AU.setPreservesAll(); 467cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak } 477cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 487cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // Return edge weight. If we don't have any informations about it - return 497cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // DEFAULT_WEIGHT. 5025101bb2a799a36be9f077ee2fc2dcf0df2b6efbJakub Staszak uint32_t getEdgeWeight(const MachineBasicBlock *Src, 5125101bb2a799a36be9f077ee2fc2dcf0df2b6efbJakub Staszak const MachineBasicBlock *Dst) const; 527cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 53990ca5517fd6666d4049b6b8281d9df99da11637Jakob Stoklund Olesen // Same thing, but using a const_succ_iterator from Src. This is faster when 54990ca5517fd6666d4049b6b8281d9df99da11637Jakob Stoklund Olesen // the iterator is already available. 55990ca5517fd6666d4049b6b8281d9df99da11637Jakob Stoklund Olesen uint32_t getEdgeWeight(const MachineBasicBlock *Src, 56990ca5517fd6666d4049b6b8281d9df99da11637Jakob Stoklund Olesen MachineBasicBlock::const_succ_iterator Dst) const; 57990ca5517fd6666d4049b6b8281d9df99da11637Jakob Stoklund Olesen 58340d596509129de8c3fa9dbe4184a2b148b78757Chandler Carruth // Get sum of the block successors' weights, potentially scaling them to fit 59340d596509129de8c3fa9dbe4184a2b148b78757Chandler Carruth // within 32-bits. If scaling is required, sets Scale based on the necessary 60340d596509129de8c3fa9dbe4184a2b148b78757Chandler Carruth // adjustment. Any edge weights used with the sum should be divided by Scale. 6125101bb2a799a36be9f077ee2fc2dcf0df2b6efbJakub Staszak uint32_t getSumForBlock(const MachineBasicBlock *MBB, uint32_t &Scale) const; 62340d596509129de8c3fa9dbe4184a2b148b78757Chandler Carruth 637cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // A 'Hot' edge is an edge which probability is >= 80%. 647cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak bool isEdgeHot(MachineBasicBlock *Src, MachineBasicBlock *Dst) const; 657cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 667cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // Return a hot successor for the block BB or null if there isn't one. 67c4e15628255b24cb17138404abe3d94bde811e25Chandler Carruth // NB: This routine's complexity is linear on the number of successors. 687cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak MachineBasicBlock *getHotSucc(MachineBasicBlock *MBB) const; 697cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 707cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // Return a probability as a fraction between 0 (0% probability) and 717cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // 1 (100% probability), however the value is never equal to 0, and can be 1 7294c22716d60ff5edf6a98a3c67e0faa001be1142Sylvestre Ledru // only iff SRC block has only one successor. 73883f2fab47ca2f7f6efebb10a5e859f5804bed07Chandler Carruth // NB: This routine's complexity is linear on the number of successors of 74883f2fab47ca2f7f6efebb10a5e859f5804bed07Chandler Carruth // Src. Querying sequentially for each successor's probability is a quadratic 75883f2fab47ca2f7f6efebb10a5e859f5804bed07Chandler Carruth // query pattern. 767cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak BranchProbability getEdgeProbability(MachineBasicBlock *Src, 777cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak MachineBasicBlock *Dst) const; 787cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 797cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // Print value between 0 (0% probability) and 1 (100% probability), 8094c22716d60ff5edf6a98a3c67e0faa001be1142Sylvestre Ledru // however the value is never equal to 0, and can be 1 only iff SRC block 817cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak // has only one successor. 827cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak raw_ostream &printEdgeProbability(raw_ostream &OS, MachineBasicBlock *Src, 837cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak MachineBasicBlock *Dst) const; 847cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak}; 857cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 867cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak} 877cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 887cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak 897cc2b07437a1243c33324549a1904fefc5f1845eJakub Staszak#endif 90