From a3d7e7e9004731ac711f106a92be487bff423b09 Mon Sep 17 00:00:00 2001 From: Dale Johannesen Date: Fri, 24 Oct 2008 21:24:23 +0000 Subject: [PATCH] Rewrite logic to figure out whether LR needs to be saved/restored in the prolog/epilog. We need to do this iff something in the function stores into it. llvm-svn: 58116 --- lib/Target/PowerPC/PPCMachineFunctionInfo.h | 20 +++++---- lib/Target/PowerPC/PPCRegisterInfo.cpp | 46 ++++++++++----------- 2 files changed, 34 insertions(+), 32 deletions(-) diff --git a/lib/Target/PowerPC/PPCMachineFunctionInfo.h b/lib/Target/PowerPC/PPCMachineFunctionInfo.h index 230ea0b0e04..42883d78728 100644 --- a/lib/Target/PowerPC/PPCMachineFunctionInfo.h +++ b/lib/Target/PowerPC/PPCMachineFunctionInfo.h @@ -31,9 +31,10 @@ private: /// int ReturnAddrSaveIndex; - /// UsesLR - Indicates whether LR is used in the current function. This is - /// only valid after the initial scan of the function by PEI. - bool UsesLR; + /// MustSaveLR - Indicates whether LR is defined (or clobbered) in the current + /// function. This is only valid after the initial scan of the function by + /// PEI. + bool MustSaveLR; /// SpillsCR - Indicates whether CR is spilled in the current function. bool SpillsCR; @@ -79,12 +80,13 @@ public: int getTailCallSPDelta() const { return TailCallSPDelta; } void setTailCallSPDelta(int size) { TailCallSPDelta = size; } - /// UsesLR - This is set when the prolog/epilog inserter does its initial scan - /// of the function, it is true if the LR/LR8 register is ever explicitly - /// accessed/clobbered in the machine function (e.g. by calls and movpctolr, - /// which is used in PIC generation). - void setUsesLR(bool U) { UsesLR = U; } - bool usesLR() const { return UsesLR; } + /// MustSaveLR - This is set when the prolog/epilog inserter does its initial + /// scan of the function. It is true if the LR/LR8 register is ever explicitly + /// defined/clobbered in the machine function (e.g. by calls and movpctolr, + /// which is used in PIC generation), or if the LR stack slot is explicitly + /// referenced by builtin_return_address. + void setMustSaveLR(bool U) { MustSaveLR = U; } + bool mustSaveLR() const { return MustSaveLR; } void setSpillsCR() { SpillsCR = true; } bool isCRSpilled() const { return SpillsCR; } diff --git a/lib/Target/PowerPC/PPCRegisterInfo.cpp b/lib/Target/PowerPC/PPCRegisterInfo.cpp index 586ad6bcf58..ae52611e1a7 100644 --- a/lib/Target/PowerPC/PPCRegisterInfo.cpp +++ b/lib/Target/PowerPC/PPCRegisterInfo.cpp @@ -389,15 +389,15 @@ bool PPCRegisterInfo::hasFP(const MachineFunction &MF) const { /// MustSaveLR - Return true if this function requires that we save the LR /// register onto the stack in the prolog and restore it in the epilog of the /// function. -static bool MustSaveLR(const MachineFunction &MF) { +static bool MustSaveLR(const MachineFunction &MF, unsigned LR) { const PPCFunctionInfo *MFI = MF.getInfo(); - // We need an save/restore of LR if there is any use/def of LR explicitly, or - // if there is some use of the LR stack slot (e.g. for builtin_return_address. - return MFI->usesLR() || MFI->isLRStoreRequired() || - // FIXME: Anything that has a call should clobber the LR register, - // isn't this redundant?? - MF.getFrameInfo()->hasCalls(); + // We need a save/restore of LR if there is any def of LR (which is + // defined by calls, including the PIC setup sequence), or if there is + // some use of the LR stack slot (e.g. for builtin_return_address). + // (LR comes in 32 and 64 bit versions.) + MachineRegisterInfo::def_iterator RI = MF.getRegInfo().def_begin(LR); + return RI !=MF.getRegInfo().def_end() || MFI->isLRStoreRequired(); } @@ -406,7 +406,7 @@ void PPCRegisterInfo:: eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, MachineBasicBlock::iterator I) const { if (PerformTailCallOpt && I->getOpcode() == PPC::ADJCALLSTACKUP) { - // Add (actually substract) back the amount the callee popped on return. + // Add (actually subtract) back the amount the callee popped on return. if (int CalleeAmt = I->getOperand(1).getImm()) { bool is64Bit = Subtarget.isPPC64(); CalleeAmt *= -1; @@ -934,7 +934,7 @@ PPCRegisterInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF, // Save and clear the LR state. PPCFunctionInfo *FI = MF.getInfo(); unsigned LR = getRARegister(); - FI->setUsesLR(MF.getRegInfo().isPhysRegUsed(LR)); + FI->setMustSaveLR(MustSaveLR(MF, LR)); MF.getRegInfo().setPhysRegUnused(LR); // Save R31 if necessary @@ -1015,8 +1015,9 @@ PPCRegisterInfo::emitPrologue(MachineFunction &MF) const { bool IsPPC64 = Subtarget.isPPC64(); // Get operating system bool IsMachoABI = Subtarget.isMachoABI(); - // Check if the link register (LR) has been used. - bool UsesLR = MustSaveLR(MF); + // Check if the link register (LR) must be saved. + PPCFunctionInfo *FI = MF.getInfo(); + bool MustSaveLR = FI->mustSaveLR(); // Do we have a frame pointer for this function? bool HasFP = hasFP(MF) && FrameSize; @@ -1024,7 +1025,7 @@ PPCRegisterInfo::emitPrologue(MachineFunction &MF) const { int FPOffset = PPCFrameInfo::getFramePointerSaveOffset(IsPPC64, IsMachoABI); if (IsPPC64) { - if (UsesLR) + if (MustSaveLR) BuildMI(MBB, MBBI, TII.get(PPC::MFLR8), PPC::X0); if (HasFP) @@ -1033,13 +1034,13 @@ PPCRegisterInfo::emitPrologue(MachineFunction &MF) const { .addImm(FPOffset/4) .addReg(PPC::X1); - if (UsesLR) + if (MustSaveLR) BuildMI(MBB, MBBI, TII.get(PPC::STD)) .addReg(PPC::X0) .addImm(LROffset / 4) .addReg(PPC::X1); } else { - if (UsesLR) + if (MustSaveLR) BuildMI(MBB, MBBI, TII.get(PPC::MFLR), PPC::R0); if (HasFP) @@ -1048,7 +1049,7 @@ PPCRegisterInfo::emitPrologue(MachineFunction &MF) const { .addImm(FPOffset) .addReg(PPC::R1); - if (UsesLR) + if (MustSaveLR) BuildMI(MBB, MBBI, TII.get(PPC::STW)) .addReg(PPC::R0) .addImm(LROffset) @@ -1222,8 +1223,9 @@ void PPCRegisterInfo::emitEpilogue(MachineFunction &MF, bool IsPPC64 = Subtarget.isPPC64(); // Get operating system bool IsMachoABI = Subtarget.isMachoABI(); - // Check if the link register (LR) has been used. - bool UsesLR = MustSaveLR(MF); + // Check if the link register (LR) has been saved. + PPCFunctionInfo *FI = MF.getInfo(); + bool MustSaveLR = FI->mustSaveLR(); // Do we have a frame pointer for this function? bool HasFP = hasFP(MF) && FrameSize; @@ -1237,8 +1239,6 @@ void PPCRegisterInfo::emitEpilogue(MachineFunction &MF, RetOpcode == PPC::TCRETURNdi8 || RetOpcode == PPC::TCRETURNai8; - PPCFunctionInfo *FI = MF.getInfo(); - if (UsesTCRet) { int MaxTCRetDelta = FI->getTailCallSPDelta(); MachineOperand &StackAdjust = MBBI->getOperand(1); @@ -1309,7 +1309,7 @@ void PPCRegisterInfo::emitEpilogue(MachineFunction &MF, } if (IsPPC64) { - if (UsesLR) + if (MustSaveLR) BuildMI(MBB, MBBI, TII.get(PPC::LD), PPC::X0) .addImm(LROffset/4).addReg(PPC::X1); @@ -1317,10 +1317,10 @@ void PPCRegisterInfo::emitEpilogue(MachineFunction &MF, BuildMI(MBB, MBBI, TII.get(PPC::LD), PPC::X31) .addImm(FPOffset/4).addReg(PPC::X1); - if (UsesLR) + if (MustSaveLR) BuildMI(MBB, MBBI, TII.get(PPC::MTLR8)).addReg(PPC::X0); } else { - if (UsesLR) + if (MustSaveLR) BuildMI(MBB, MBBI, TII.get(PPC::LWZ), PPC::R0) .addImm(LROffset).addReg(PPC::R1); @@ -1328,7 +1328,7 @@ void PPCRegisterInfo::emitEpilogue(MachineFunction &MF, BuildMI(MBB, MBBI, TII.get(PPC::LWZ), PPC::R31) .addImm(FPOffset).addReg(PPC::R1); - if (UsesLR) + if (MustSaveLR) BuildMI(MBB, MBBI, TII.get(PPC::MTLR)).addReg(PPC::R0); }