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Fix incorrect choice of callee-saved registers save/restore points 

Make the shrink wrapping pass pay attention to uses/defs of the stack pointer.

Differential revision: https://reviews.llvm.org/D45524

llvm-svn: 330183
This commit is contained in:
Momchil Velikov 2018-04-17 08:37:38 +00:00
parent e54b7ff670
commit e256ab847b
1 changed files with 14 additions and 2 deletions
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16
llvm/lib/CodeGen/ShrinkWrap.cpp
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@ -68,6 +68,7 @@
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/CodeGen/TargetFrameLowering.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/Attributes.h"
@ -138,6 +139,9 @@ class ShrinkWrap : public MachineFunctionPass {
/// Current opcode for frame destroy.
unsigned FrameDestroyOpcode;
/// Stack pointer register, used by llvm.{savestack,restorestack}
unsigned SP;
/// Entry block.
const MachineBasicBlock *Entry;
@ -186,9 +190,11 @@ class ShrinkWrap : public MachineFunctionPass {
MBFI = &getAnalysis<MachineBlockFrequencyInfo>();
MLI = &getAnalysis<MachineLoopInfo>();
EntryFreq = MBFI->getEntryFreq();
const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
const TargetSubtargetInfo &Subtarget = MF.getSubtarget();
const TargetInstrInfo &TII = *Subtarget.getInstrInfo();
FrameSetupOpcode = TII.getCallFrameSetupOpcode();
FrameDestroyOpcode = TII.getCallFrameDestroyOpcode();
SP = Subtarget.getTargetLowering()->getStackPointerRegisterToSaveRestore();
Entry = &MF.front();
CurrentCSRs.clear();
MachineFunc = &MF;
@ -262,7 +268,13 @@ bool ShrinkWrap::useOrDefCSROrFI(const MachineInstr &MI,
continue;
assert(TargetRegisterInfo::isPhysicalRegister(PhysReg) &&
"Unallocated register?!");
UseOrDefCSR = RCI.getLastCalleeSavedAlias(PhysReg);
// The stack pointer is not normally described as a callee-saved register
// in calling convention definitions, so we need to watch for it
// separately. An SP mentioned by a call instruction, we can ignore,
// though, as it's harmless and we do not want to effectively disable tail
// calls by forcing the restore point to post-dominate them.
UseOrDefCSR = (!MI.isCall() && PhysReg == SP) ||
RCI.getLastCalleeSavedAlias(PhysReg);
} else if (MO.isRegMask()) {
// Check if this regmask clobbers any of the CSRs.
for (unsigned Reg : getCurrentCSRs(RS)) {