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[AArch64] Clean up callee-save CFI emission. NFC. 

Summary:
Avoid special case for FP, LR CFI emission and just allow general
AArch64FrameLowering::emitCalleeSavedFrameMoves() to handle them.  Also,
stop recalculating the stack offsets in emitCalleeSavedFrameMoves()
since we can just reuse the previously calculated offset stored in the
MachineFrameInfo.

Depends on D17000

Reviewers: t.p.northover, rengolin, mcrosier, jmolloy

Subscribers: aemerson, rengolin, mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D17004

llvm-svn: 261885
This commit is contained in:
Geoff Berry 2016-02-25 16:36:08 +00:00
parent 2fa386fd6c
commit 62d472507e
2 changed files with 9 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

52
llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
View File

@ -202,8 +202,7 @@ void AArch64FrameLowering::eliminateCallFramePseudoInstr(
} }
void AArch64FrameLowering::emitCalleeSavedFrameMoves( void AArch64FrameLowering::emitCalleeSavedFrameMoves(
MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI) const {
unsigned FramePtr) const {
MachineFunction &MF = *MBB.getParent(); MachineFunction &MF = *MBB.getParent();
MachineFrameInfo *MFI = MF.getFrameInfo(); MachineFrameInfo *MFI = MF.getFrameInfo();
MachineModuleInfo &MMI = MF.getMMI(); MachineModuleInfo &MMI = MF.getMMI();
@ -216,34 +215,13 @@ void AArch64FrameLowering::emitCalleeSavedFrameMoves(
if (CSI.empty()) if (CSI.empty())
return; return;
const DataLayout &TD = MF.getDataLayout();
bool HasFP = hasFP(MF);
// Calculate amount of bytes used for return address storing.
int stackGrowth = -TD.getPointerSize(0);
// Calculate offsets.
int64_t saveAreaOffset = (HasFP ? 2 : 1) * stackGrowth;
unsigned TotalSkipped = 0;
for (const auto &Info : CSI) { for (const auto &Info : CSI) {
unsigned Reg = Info.getReg(); unsigned Reg = Info.getReg();
int64_t Offset = MFI->getObjectOffset(Info.getFrameIdx()) - int64_t Offset =
getOffsetOfLocalArea() + saveAreaOffset; MFI->getObjectOffset(Info.getFrameIdx()) - getOffsetOfLocalArea();
// Don't output a new CFI directive if we're re-saving the frame pointer or
// link register. This happens when the PrologEpilogInserter has inserted an
// extra "STP" of the frame pointer and link register -- the "emitPrologue"
// method automatically generates the directives when frame pointers are
// used. If we generate CFI directives for the extra "STP"s, the linker will
// lose track of the correct values for the frame pointer and link register.
if (HasFP && (FramePtr == Reg || Reg == AArch64::LR)) {
TotalSkipped += stackGrowth;
continue;
}
unsigned DwarfReg = MRI->getDwarfRegNum(Reg, true); unsigned DwarfReg = MRI->getDwarfRegNum(Reg, true);
unsigned CFIIndex = MMI.addFrameInst(MCCFIInstruction::createOffset( unsigned CFIIndex = MMI.addFrameInst(
nullptr, DwarfReg, Offset - TotalSkipped)); MCCFIInstruction::createOffset(nullptr, DwarfReg, Offset));
BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION)) BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex) .addCFIIndex(CFIIndex)
.setMIFlags(MachineInstr::FrameSetup); .setMIFlags(MachineInstr::FrameSetup);
@ -512,21 +490,6 @@ void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION)) BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex) .addCFIIndex(CFIIndex)
.setMIFlags(MachineInstr::FrameSetup); .setMIFlags(MachineInstr::FrameSetup);
// Record the location of the stored LR
unsigned LR = RegInfo->getDwarfRegNum(AArch64::LR, true);
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createOffset(nullptr, LR, StackGrowth));
BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex)
.setMIFlags(MachineInstr::FrameSetup);
// Record the location of the stored FP
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg, 2 * StackGrowth));
BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex)
.setMIFlags(MachineInstr::FrameSetup);
} else { } else {
// Encode the stack size of the leaf function. // Encode the stack size of the leaf function.
unsigned CFIIndex = MMI.addFrameInst( unsigned CFIIndex = MMI.addFrameInst(
@ -536,8 +499,9 @@ void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
.setMIFlags(MachineInstr::FrameSetup); .setMIFlags(MachineInstr::FrameSetup);
} }
// Now emit the moves for whatever callee saved regs we have. // Now emit the moves for whatever callee saved regs we have (including FP,
emitCalleeSavedFrameMoves(MBB, MBBI, FramePtr); // LR if those are saved).
emitCalleeSavedFrameMoves(MBB, MBBI);
} }
} }

3
llvm/lib/Target/AArch64/AArch64FrameLowering.h
View File

@ -25,8 +25,7 @@ public:
true /*StackRealignable*/) {} true /*StackRealignable*/) {}
void emitCalleeSavedFrameMoves(MachineBasicBlock &MBB, void emitCalleeSavedFrameMoves(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI, MachineBasicBlock::iterator MBBI) const;
unsigned FramePtr) const;
void eliminateCallFramePseudoInstr(MachineFunction &MF, void eliminateCallFramePseudoInstr(MachineFunction &MF,
MachineBasicBlock &MBB, MachineBasicBlock &MBB,