From 3280da3cda96c43764bd6680d2e2021dedcfc051 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Wed, 11 Jan 2006 23:03:54 +0000 Subject: [PATCH] If a function has a non-zero sized frame, use an add to adjust the stack pointer in the epilog, not a load. llvm-svn: 25229 --- llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp | 29 ++++++++++++++------- 1 file changed, 20 insertions(+), 9 deletions(-) diff --git a/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp b/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp index ae136cbc420a..febbb47e13f7 100644 --- a/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp +++ b/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp @@ -370,23 +370,34 @@ void PPCRegisterInfo::emitPrologue(MachineFunction &MF) const { void PPCRegisterInfo::emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const { - const MachineFrameInfo *MFI = MF.getFrameInfo(); MachineBasicBlock::iterator MBBI = prior(MBB.end()); - MachineInstr *MI; assert(MBBI->getOpcode() == PPC::BLR && "Can only insert epilog into returning blocks"); - // Get the number of bytes allocated from the FrameInfo... - unsigned NumBytes = MFI->getStackSize(); - unsigned GPRSize = 4; + // Get the number of bytes allocated from the FrameInfo. + unsigned NumBytes = MF.getFrameInfo()->getStackSize(); + unsigned GPRSize = 4; if (NumBytes != 0) { + // If this function has a frame pointer, load the saved stack pointer from + // its stack slot. if (hasFP(MF)) { - MI = BuildMI(PPC::LWZ, 2, PPC::R31).addSImm(GPRSize).addReg(PPC::R31); - MBB.insert(MBBI, MI); + BuildMI(MBB, MBBI, PPC::LWZ, 2, PPC::R31) + .addSImm(GPRSize).addReg(PPC::R31); + } + + // The loaded (or persistent) stack pointer value is offseted by the 'stwu' + // on entry to the function. Add this offset back now. + if (NumBytes <= 32768) { + BuildMI(MBB, MBBI, PPC::ADDI, 2, PPC::R1) + .addReg(PPC::R1).addSImm(NumBytes); + } else { + BuildMI(MBB, MBBI, PPC::LIS, 1, PPC::R0).addSImm(NumBytes >> 16); + BuildMI(MBB, MBBI, PPC::ORI, 2, PPC::R0) + .addReg(PPC::R0).addImm(NumBytes & 0xFFFF); + BuildMI(MBB, MBBI, PPC::ADD4, 2, PPC::R1) + .addReg(PPC::R0).addReg(PPC::R1); } - MI = BuildMI(PPC::LWZ, 2, PPC::R1).addSImm(0).addReg(PPC::R1); - MBB.insert(MBBI, MI); } }