TargetFrameLowering.h revision 16c29b5f285f375be53dabaa73e3e91107485fe4
116c29b5f285f375be53dabaa73e3e91107485fe4Anton Korobeynikov//===-- llvm/Target/TargetFrameLowering.h ---------------------------*- C++ -*-===// 234695381d626485a560594f162701088079589dfMisha Brukman// 36fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell// The LLVM Compiler Infrastructure 46fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell// 57ed47a13356daed2a34cd2209a31f92552e3bdd8Chris Lattner// This file is distributed under the University of Illinois Open Source 67ed47a13356daed2a34cd2209a31f92552e3bdd8Chris Lattner// License. See LICENSE.TXT for details. 734695381d626485a560594f162701088079589dfMisha Brukman// 86fbcc26f1460eaee4e0eb8b426fc1ff0c7af11beJohn Criswell//===----------------------------------------------------------------------===// 9035dfbe7f2d109008d2d62d9f2a67efb477a7ab6Chris Lattner// 10fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner// Interface to describe the layout of a stack frame on the target machine. 11035dfbe7f2d109008d2d62d9f2a67efb477a7ab6Chris Lattner// 12035dfbe7f2d109008d2d62d9f2a67efb477a7ab6Chris Lattner//===----------------------------------------------------------------------===// 137cffcaaa48656fa6f90b041cc5f056304addef32Vikram S. Adve 1416c29b5f285f375be53dabaa73e3e91107485fe4Anton Korobeynikov#ifndef LLVM_TARGET_TARGETFRAMELOWERING_H 1516c29b5f285f375be53dabaa73e3e91107485fe4Anton Korobeynikov#define LLVM_TARGET_TARGETFRAMELOWERING_H 167cffcaaa48656fa6f90b041cc5f056304addef32Vikram S. Adve 17cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov#include "llvm/CodeGen/MachineBasicBlock.h" 18cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov 1909431e187f9abd45af08461df728204ee9731fd7Chris Lattner#include <utility> 20d9e3385ced2dc887e2fe8e1c071bd2611e4d3edeAnton Korobeynikov#include <vector> 2109431e187f9abd45af08461df728204ee9731fd7Chris Lattner 22d0fde30ce850b78371fd1386338350591f9ff494Brian Gaekenamespace llvm { 23cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov class CalleeSavedInfo; 2433464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov class MachineFunction; 2533464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov class MachineBasicBlock; 26d9e3385ced2dc887e2fe8e1c071bd2611e4d3edeAnton Korobeynikov class MachineMove; 2794c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov class RegScavenger; 28d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 29c07c0df634d31849ac659234e4718b57ddacb882Chris Lattner/// Information about stack frame layout on the target. It holds the direction 30c07c0df634d31849ac659234e4718b57ddacb882Chris Lattner/// of stack growth, the known stack alignment on entry to each function, and 31c07c0df634d31849ac659234e4718b57ddacb882Chris Lattner/// the offset to the locals area. 32c07c0df634d31849ac659234e4718b57ddacb882Chris Lattner/// 33c07c0df634d31849ac659234e4718b57ddacb882Chris Lattner/// The offset to the local area is the offset from the stack pointer on 34c07c0df634d31849ac659234e4718b57ddacb882Chris Lattner/// function entry to the first location where function data (local variables, 35c07c0df634d31849ac659234e4718b57ddacb882Chris Lattner/// spill locations) can be stored. 3616c29b5f285f375be53dabaa73e3e91107485fe4Anton Korobeynikovclass TargetFrameLowering { 371fca5ff62bb2ecb5bfc8974f4dbfc56e9d3ca721Chris Lattnerpublic: 38fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner enum StackDirection { 39fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner StackGrowsUp, // Adding to the stack increases the stack address 40fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner StackGrowsDown // Adding to the stack decreases the stack address 41fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner }; 428ff95de83cbe85d939535d2f4fb5f9b2b721081aTilmann Scheller 438ff95de83cbe85d939535d2f4fb5f9b2b721081aTilmann Scheller // Maps a callee saved register to a stack slot with a fixed offset. 448ff95de83cbe85d939535d2f4fb5f9b2b721081aTilmann Scheller struct SpillSlot { 458ff95de83cbe85d939535d2f4fb5f9b2b721081aTilmann Scheller unsigned Reg; 468ff95de83cbe85d939535d2f4fb5f9b2b721081aTilmann Scheller int Offset; // Offset relative to stack pointer on function entry. 478ff95de83cbe85d939535d2f4fb5f9b2b721081aTilmann Scheller }; 48fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattnerprivate: 49fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner StackDirection StackDir; 50fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner unsigned StackAlignment; 510035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson unsigned TransientStackAlignment; 52fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner int LocalAreaOffset; 537cffcaaa48656fa6f90b041cc5f056304addef32Vikram S. Advepublic: 5416c29b5f285f375be53dabaa73e3e91107485fe4Anton Korobeynikov TargetFrameLowering(StackDirection D, unsigned StackAl, int LAO, 5516c29b5f285f375be53dabaa73e3e91107485fe4Anton Korobeynikov unsigned TransAl = 1) 560035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson : StackDir(D), StackAlignment(StackAl), TransientStackAlignment(TransAl), 570035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson LocalAreaOffset(LAO) {} 58fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner 5916c29b5f285f375be53dabaa73e3e91107485fe4Anton Korobeynikov virtual ~TargetFrameLowering(); 60a1aad3b0eda2a516f663cb5f9f8c4c9bbb6ef224Reid Spencer 61fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner // These methods return information that describes the abstract stack layout 62fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner // of the target machine. 63fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner 64fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner /// getStackGrowthDirection - Return the direction the stack grows 65fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner /// 66fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner StackDirection getStackGrowthDirection() const { return StackDir; } 67fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner 680035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson /// getStackAlignment - This method returns the number of bytes to which the 690035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson /// stack pointer must be aligned on entry to a function. Typically, this 700035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson /// is the largest alignment for any data object in the target. 71fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner /// 72fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner unsigned getStackAlignment() const { return StackAlignment; } 73fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner 740035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson /// getTransientStackAlignment - This method returns the number of bytes to 750035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson /// which the stack pointer must be aligned at all times, even between 760035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson /// calls. 770035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson /// 780035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson unsigned getTransientStackAlignment() const { 790035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson return TransientStackAlignment; 800035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson } 810035f9c3b9982eeef098b608fceb7572df969b3eBob Wilson 82fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner /// getOffsetOfLocalArea - This method returns the offset of the local area 83fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner /// from the stack pointer on entrance to a function. 84fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner /// 85fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner int getOffsetOfLocalArea() const { return LocalAreaOffset; } 86fd529d2e4aed9a455d539962248fda8583d6ba8eChris Lattner 870098b3e2b69e527ddcf2ebad7a3081898fa3b4f0Evan Cheng /// getCalleeSavedSpillSlots - This method returns a pointer to an array of 880098b3e2b69e527ddcf2ebad7a3081898fa3b4f0Evan Cheng /// pairs, that contains an entry for each callee saved register that must be 8909431e187f9abd45af08461df728204ee9731fd7Chris Lattner /// spilled to a particular stack location if it is spilled. 9009431e187f9abd45af08461df728204ee9731fd7Chris Lattner /// 9109431e187f9abd45af08461df728204ee9731fd7Chris Lattner /// Each entry in this array contains a <register,offset> pair, indicating the 9209431e187f9abd45af08461df728204ee9731fd7Chris Lattner /// fixed offset from the incoming stack pointer that each register should be 938ff95de83cbe85d939535d2f4fb5f9b2b721081aTilmann Scheller /// spilled at. If a register is not listed here, the code generator is 9409431e187f9abd45af08461df728204ee9731fd7Chris Lattner /// allowed to spill it anywhere it chooses. 9534695381d626485a560594f162701088079589dfMisha Brukman /// 968ff95de83cbe85d939535d2f4fb5f9b2b721081aTilmann Scheller virtual const SpillSlot * 970098b3e2b69e527ddcf2ebad7a3081898fa3b4f0Evan Cheng getCalleeSavedSpillSlots(unsigned &NumEntries) const { 9809431e187f9abd45af08461df728204ee9731fd7Chris Lattner NumEntries = 0; 9909431e187f9abd45af08461df728204ee9731fd7Chris Lattner return 0; 10009431e187f9abd45af08461df728204ee9731fd7Chris Lattner } 10133464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov 10233464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov /// targetHandlesStackFrameRounding - Returns true if the target is 10333464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov /// responsible for rounding up the stack frame (probably at emitPrologue 10433464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov /// time). 10533464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov virtual bool targetHandlesStackFrameRounding() const { 10633464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov return false; 10733464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov } 10833464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov 10933464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov /// emitProlog/emitEpilog - These methods insert prolog and epilog code into 11033464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov /// the function. 11133464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov virtual void emitPrologue(MachineFunction &MF) const = 0; 11233464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov virtual void emitEpilogue(MachineFunction &MF, 11333464912237efaa0ed7060829e66b59055bdd48bAnton Korobeynikov MachineBasicBlock &MBB) const = 0; 114d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov 115cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov /// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee 116cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov /// saved registers and returns true if it isn't possible / profitable to do 117cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov /// so by issuing a series of store instructions via 118cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov /// storeRegToStackSlot(). Returns false otherwise. 119cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB, 120cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov MachineBasicBlock::iterator MI, 121cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov const std::vector<CalleeSavedInfo> &CSI, 122cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov const TargetRegisterInfo *TRI) const { 123cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov return false; 124cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov } 125cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov 126cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov /// restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee 127cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov /// saved registers and returns true if it isn't possible / profitable to do 128cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov /// so by issuing a series of load instructions via loadRegToStackSlot(). 129cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov /// Returns false otherwise. 130cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB, 131cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov MachineBasicBlock::iterator MI, 132cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov const std::vector<CalleeSavedInfo> &CSI, 133cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov const TargetRegisterInfo *TRI) const { 134cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov return false; 135cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov } 136cd775ceff0b25a0b026f643a7990c2924bd310a3Anton Korobeynikov 137d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// hasFP - Return true if the specified function should have a dedicated 138d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// frame pointer register. For most targets this is true only if the function 139d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// has variable sized allocas or if frame pointer elimination is disabled. 140d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov virtual bool hasFP(const MachineFunction &MF) const = 0; 141d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov 142d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// hasReservedCallFrame - Under normal circumstances, when a frame pointer is 143d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// not required, we reserve argument space for call sites in the function 144d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// immediately on entry to the current function. This eliminates the need for 145d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// add/sub sp brackets around call sites. Returns true if the call frame is 146d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// included as part of the stack frame. 147d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov virtual bool hasReservedCallFrame(const MachineFunction &MF) const { 148d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov return !hasFP(MF); 149d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov } 150d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov 151d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// canSimplifyCallFramePseudos - When possible, it's best to simplify the 152d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// call frame pseudo ops before doing frame index elimination. This is 153d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// possible only when frame index references between the pseudos won't 154d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// need adjusting for the call frame adjustments. Normally, that's true 155d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// if the function has a reserved call frame or a frame pointer. Some 156d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// targets (Thumb2, for example) may have more complicated criteria, 157d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov /// however, and can override this behavior. 158d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov virtual bool canSimplifyCallFramePseudos(const MachineFunction &MF) const { 159d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov return hasReservedCallFrame(MF) || hasFP(MF); 160d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov } 161d0c38176690e9602a93a20a43f1bd084564a8116Anton Korobeynikov 162d9e3385ced2dc887e2fe8e1c071bd2611e4d3edeAnton Korobeynikov /// getInitialFrameState - Returns a list of machine moves that are assumed 163d9e3385ced2dc887e2fe8e1c071bd2611e4d3edeAnton Korobeynikov /// on entry to all functions. Note that LabelID is ignored (assumed to be 164d9e3385ced2dc887e2fe8e1c071bd2611e4d3edeAnton Korobeynikov /// the beginning of the function.) 165d9e3385ced2dc887e2fe8e1c071bd2611e4d3edeAnton Korobeynikov virtual void getInitialFrameState(std::vector<MachineMove> &Moves) const; 16682f58740c76b42af8370247b23677a0318f6dde8Anton Korobeynikov 16782f58740c76b42af8370247b23677a0318f6dde8Anton Korobeynikov /// getFrameIndexOffset - Returns the displacement from the frame register to 16882f58740c76b42af8370247b23677a0318f6dde8Anton Korobeynikov /// the stack frame of the specified index. 16982f58740c76b42af8370247b23677a0318f6dde8Anton Korobeynikov virtual int getFrameIndexOffset(const MachineFunction &MF, int FI) const; 17082f58740c76b42af8370247b23677a0318f6dde8Anton Korobeynikov 17182f58740c76b42af8370247b23677a0318f6dde8Anton Korobeynikov /// getFrameIndexReference - This method should return the base register 17282f58740c76b42af8370247b23677a0318f6dde8Anton Korobeynikov /// and offset used to reference a frame index location. The offset is 17382f58740c76b42af8370247b23677a0318f6dde8Anton Korobeynikov /// returned directly, and the base register is returned via FrameReg. 17482f58740c76b42af8370247b23677a0318f6dde8Anton Korobeynikov virtual int getFrameIndexReference(const MachineFunction &MF, int FI, 17582f58740c76b42af8370247b23677a0318f6dde8Anton Korobeynikov unsigned &FrameReg) const; 17694c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov 17794c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov /// processFunctionBeforeCalleeSavedScan - This method is called immediately 17894c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov /// before PrologEpilogInserter scans the physical registers used to determine 17994c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov /// what callee saved registers should be spilled. This method is optional. 18094c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov virtual void processFunctionBeforeCalleeSavedScan(MachineFunction &MF, 18194c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov RegScavenger *RS = NULL) const { 18294c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov 18394c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov } 18494c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov 18594c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov /// processFunctionBeforeFrameFinalized - This method is called immediately 18694c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov /// before the specified function's frame layout (MF.getFrameInfo()) is 18794c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov /// finalized. Once the frame is finalized, MO_FrameIndex operands are 18894c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov /// replaced with direct constants. This method is optional. 18994c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov /// 19094c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov virtual void processFunctionBeforeFrameFinalized(MachineFunction &MF) const { 19194c5ae08750f314bc3cf1bf882b686244a3927d9Anton Korobeynikov } 1927cffcaaa48656fa6f90b041cc5f056304addef32Vikram S. Adve}; 1937cffcaaa48656fa6f90b041cc5f056304addef32Vikram S. Adve 194d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke} // End llvm namespace 195d0fde30ce850b78371fd1386338350591f9ff494Brian Gaeke 1967cffcaaa48656fa6f90b041cc5f056304addef32Vikram S. Adve#endif 197