From 51195af45f4142035f23c7d58d1311face3900a4 Mon Sep 17 00:00:00 2001 From: Bruno Cardoso Lopes Date: Tue, 28 Aug 2007 05:13:42 +0000 Subject: [PATCH] Added method to get Mips register numbers Changed the stack frame layout, StackGrowsUp fits better to Mips strange stack. Stack offset calculation bug fixed! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41529 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/Mips/MipsRegisterInfo.cpp | 156 +++++++++++++++++--------- lib/Target/Mips/MipsRegisterInfo.h | 9 +- lib/Target/Mips/MipsTargetMachine.cpp | 9 +- 3 files changed, 113 insertions(+), 61 deletions(-) diff --git a/lib/Target/Mips/MipsRegisterInfo.cpp b/lib/Target/Mips/MipsRegisterInfo.cpp index 5d78d902c98..a946e46fa54 100644 --- a/lib/Target/Mips/MipsRegisterInfo.cpp +++ b/lib/Target/Mips/MipsRegisterInfo.cpp @@ -41,6 +41,48 @@ MipsRegisterInfo::MipsRegisterInfo(const TargetInstrInfo &tii) : MipsGenRegisterInfo(Mips::ADJCALLSTACKDOWN, Mips::ADJCALLSTACKUP), TII(tii) {} +/// getRegisterNumbering - Given the enum value for some register, e.g. +/// Mips::RA, return the number that it corresponds to (e.g. 31). +unsigned MipsRegisterInfo:: +getRegisterNumbering(unsigned RegEnum) +{ + switch (RegEnum) { + case Mips::ZERO : return 0; + case Mips::AT : return 1; + case Mips::V0 : return 2; + case Mips::V1 : return 3; + case Mips::A0 : return 4; + case Mips::A1 : return 5; + case Mips::A2 : return 6; + case Mips::A3 : return 7; + case Mips::T0 : return 8; + case Mips::T1 : return 9; + case Mips::T2 : return 10; + case Mips::T3 : return 11; + case Mips::T4 : return 12; + case Mips::T5 : return 13; + case Mips::T6 : return 14; + case Mips::T7 : return 15; + case Mips::T8 : return 16; + case Mips::T9 : return 17; + case Mips::S0 : return 18; + case Mips::S1 : return 19; + case Mips::S2 : return 20; + case Mips::S3 : return 21; + case Mips::S4 : return 22; + case Mips::S5 : return 23; + case Mips::S6 : return 24; + case Mips::S7 : return 25; + case Mips::K0 : return 26; + case Mips::K1 : return 27; + case Mips::GP : return 28; + case Mips::SP : return 29; + case Mips::FP : return 30; + case Mips::RA : return 31; + default: assert(0 && "Unknown register number!"); + } +} + void MipsRegisterInfo:: storeRegToStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I, unsigned SrcReg, int FI, @@ -114,6 +156,12 @@ foldMemoryOperand(MachineInstr* MI, unsigned OpNum, int FI) const return NewMI; } +//===----------------------------------------------------------------------===// +// +// Callee Saved Registers methods +// +//===----------------------------------------------------------------------===// + /// Mips Callee Saved Registers const unsigned* MipsRegisterInfo:: getCalleeSavedRegs(const MachineFunction *MF) const @@ -159,49 +207,50 @@ getReservedRegs(const MachineFunction &MF) const // Stack Frame Processing methods // +----------------------------+ // -// Too meet ABI, we construct the frame on the reverse -// of natural order. +// The stack is allocated decrementing the stack pointer on +// the first instruction of a function prologue. Once decremented, +// all stack referencesare are done thought a positive offset +// from the stack/frame pointer, so the stack is considering +// to grow up! Otherwise terrible hacks would have to be made +// to get this stack ABI compliant :) // -// The LLVM Frame will look like this: +// The stack frame required by the ABI: +// Offset // -// As the stack grows down, we start at 0, and the reference -// is decrement. +// 0 ---------- +// 4 Args to pass +// . saved $GP (used in PIC - not supported yet) +// . Local Area +// . saved "Callee Saved" Registers +// . saved FP +// . saved RA +// StackSize ----------- // -// 0 ---------- -// -4 Args to pass -// . saved "Callee Saved" Registers -// . Local Area -// . saved FP -// . saved RA -// -StackSize ----------- -// -// On the EliminateFrameIndex we just negate the address above -// and we get the stack frame required by the ABI, which is: -// -// sp + stacksize ------------- -// saved $RA (only on non-leaf functions) -// saved $FP (only with frame pointer) -// saved "Callee Saved" Registers -// Local Area -// saved $GP (used in PIC - not supported yet) -// Args to pass area -// sp ------------- +// Offset - offset from sp after stack allocation on function prologue // // The sp is the stack pointer subtracted/added from the stack size // at the Prologue/Epilogue // // References to the previous stack (to obtain arguments) are done -// with fixed location stack frames using positive stack offsets. +// with offsets that exceeds the stack size: (stacksize+(4*(num_arg-1)) // // Examples: // - reference to the actual stack frame -// for any local area var there is smt like : FI >= 0, StackOffset: -4 -// sw REGX, 4(REGY) +// for any local area var there is smt like : FI >= 0, StackOffset: 4 +// sw REGX, 4(SP) // // - reference to previous stack frame -// suppose there's a store to the 5th arguments : FI < 0, StackOffset: 16. +// suppose there's a load to the 5th arguments : FI < 0, StackOffset: 16. // The emitted instruction will be something like: -// sw REGX, 16+StackSize (REGY) +// lw REGX, 16+StackSize(SP) +// +// Since the total stack size is unknown on LowerFORMAL_ARGUMENTS, all +// stack references (ObjectOffset) created to reference the function +// arguments, are negative numbers. This way, on eliminateFrameIndex it's +// possible to detect those references and the offsets are adjusted to +// their real location. +// +// // //===----------------------------------------------------------------------===// @@ -252,7 +301,10 @@ eliminateFrameIndex(MachineBasicBlock::iterator II, int SPAdj, DOUT << "stackSize : " << stackSize << "\n"; #endif - int Offset = ( (spOffset >= 0) ? (stackSize + spOffset) : (-spOffset)); + // as explained on LowerFORMAL_ARGUMENTS, detect negative offsets + // and adjust SPOffsets considering the final stack size. + int Offset = ((spOffset < 0) ? (stackSize + (-(spOffset+4))) : (spOffset)); + Offset += MI.getOperand(i-1).getImm(); #ifndef NDEBUG DOUT << "Offset : " << Offset << "\n"; @@ -271,50 +323,51 @@ emitPrologue(MachineFunction &MF) const MipsFunctionInfo *MipsFI = MF.getInfo(); MachineBasicBlock::iterator MBBI = MBB.begin(); + // Replace the dummy '0' SPOffset by the negative offsets, as + // explained on LowerFORMAL_ARGUMENTS + MipsFI->adjustLoadArgsFI(MFI); + MipsFI->adjustStoreVarArgsFI(MFI); + // Get the number of bytes to allocate from the FrameInfo. int NumBytes = (int) MFI->getStackSize(); #ifndef NDEBUG DOUT << "\n<--- EMIT PROLOGUE --->\n"; - DOUT << "Stack size :" << NumBytes << "\n"; + DOUT << "Actual Stack size :" << NumBytes << "\n"; #endif - // Don't need to allocate space on the stack. + // No need to allocate space on the stack. if (NumBytes == 0) return; int FPOffset, RAOffset; - // Always allocate space for saved RA and FP, - // even if FramePointer is not used. When not - // using FP, the last stack slot becomes empty - // and RA is saved before it. + // Allocate space for saved RA and FP when needed if ((hasFP(MF)) && (MFI->hasCalls())) { - FPOffset = NumBytes+4; - RAOffset = (NumBytes+8); + FPOffset = NumBytes; + RAOffset = (NumBytes+4); + NumBytes += 8; } else if ((!hasFP(MF)) && (MFI->hasCalls())) { FPOffset = 0; - RAOffset = NumBytes+4; + RAOffset = NumBytes; + NumBytes += 4; } else if ((hasFP(MF)) && (!MFI->hasCalls())) { - FPOffset = NumBytes+4; + FPOffset = NumBytes; RAOffset = 0; + NumBytes += 4; } - MFI->setObjectOffset(MFI->CreateStackObject(4,4), -FPOffset); - MFI->setObjectOffset(MFI->CreateStackObject(4,4), -RAOffset); + MFI->setObjectOffset(MFI->CreateStackObject(4,4), FPOffset); + MFI->setObjectOffset(MFI->CreateStackObject(4,4), RAOffset); MipsFI->setFPStackOffset(FPOffset); MipsFI->setRAStackOffset(RAOffset); - #ifndef NDEBUG - DOUT << "FPOffset :" << FPOffset << "\n"; - DOUT << "RAOffset :" << RAOffset << "\n"; - #endif - // Align stack. - NumBytes += 12; unsigned Align = MF.getTarget().getFrameInfo()->getStackAlignment(); NumBytes = ((NumBytes+Align-1)/Align*Align); #ifndef NDEBUG + DOUT << "FPOffset :" << FPOffset << "\n"; + DOUT << "RAOffset :" << RAOffset << "\n"; DOUT << "New stack size :" << NumBytes << "\n\n"; #endif @@ -359,13 +412,6 @@ emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const int FPOffset = MipsFI->getFPStackOffset(); int RAOffset = MipsFI->getRAStackOffset(); - #ifndef NDEBUG - DOUT << "\n<--- EMIT EPILOGUE --->" << "\n"; - DOUT << "Stack size :" << NumBytes << "\n"; - DOUT << "FPOffset :" << FPOffset << "\n"; - DOUT << "RAOffset :" << RAOffset << "\n\n"; - #endif - // if framepointer enabled, restore it and restore the // stack pointer if (hasFP(MF)) { diff --git a/lib/Target/Mips/MipsRegisterInfo.h b/lib/Target/Mips/MipsRegisterInfo.h index ebc0318b88a..cc8215c8649 100644 --- a/lib/Target/Mips/MipsRegisterInfo.h +++ b/lib/Target/Mips/MipsRegisterInfo.h @@ -27,6 +27,10 @@ struct MipsRegisterInfo : public MipsGenRegisterInfo { MipsRegisterInfo(const TargetInstrInfo &tii); + /// getRegisterNumbering - Given the enum value for some register, e.g. + /// Mips::RA, return the number that it corresponds to (e.g. 31). + static unsigned getRegisterNumbering(unsigned RegEnum); + /// Code Generation virtual methods... void storeRegToStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, @@ -62,6 +66,7 @@ struct MipsRegisterInfo : public MipsGenRegisterInfo { MachineBasicBlock &MBB, MachineBasicBlock::iterator I) const; + /// Stack Frame Processing Methods void eliminateFrameIndex(MachineBasicBlock::iterator II, int SPAdj, RegScavenger *RS = NULL) const; @@ -70,11 +75,11 @@ struct MipsRegisterInfo : public MipsGenRegisterInfo { void emitPrologue(MachineFunction &MF) const; void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const; - // Debug information queries. + /// Debug information queries. unsigned getRARegister() const; unsigned getFrameRegister(MachineFunction &MF) const; - // Exception handling queries. + /// Exception handling queries. unsigned getEHExceptionRegister() const; unsigned getEHHandlerRegister() const; }; diff --git a/lib/Target/Mips/MipsTargetMachine.cpp b/lib/Target/Mips/MipsTargetMachine.cpp index 95db8242c76..372e267d462 100644 --- a/lib/Target/Mips/MipsTargetMachine.cpp +++ b/lib/Target/Mips/MipsTargetMachine.cpp @@ -31,13 +31,14 @@ createTargetAsmInfo() const } // DataLayout --> Big-endian, 32-bit pointer/ABI/alignment -// -// FrameInfo --> StackGrowsDown, 8 bytes aligned, -// LOA : 0 +// The stack is always 8 byte aligned +// On function prologue, the stack is created by decrementing +// its pointer. Once decremented, all references are done with positive +// offset from the stack/frame pointer, so StackGrowsUp is used. MipsTargetMachine:: MipsTargetMachine(const Module &M, const std::string &FS): Subtarget(*this, M, FS), DataLayout("E-p:32:32:32"), - InstrInfo(*this), FrameInfo(TargetFrameInfo::StackGrowsDown, 8, 0), + InstrInfo(*this), FrameInfo(TargetFrameInfo::StackGrowsUp, 8, 0), TLInfo(*this) {} // return 0 and must specify -march to gen MIPS code.