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[XCore] Fix handling of functions where only the LR is spilled.

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Previously we only checked if the LR required saving if the frame size was
non zero. However because the caller reserves 1 word for the callee to use
that doesn't count towards our frame size it is possible for the LR to need
saving and for the frame size to be 0.

We didn't hit when the LR needed saving because of a function calls because
the 1 word of stack we must allocate for our callee means the frame size
is always non zero in this case. However we can hit this case if the LR is
clobbered in inline asm.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181520 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Richard Osborne 2013-05-09 16:43:42 +00:00
parent a6ff92a975
commit 9bd913c4c1
2 changed files with 41 additions and 27 deletions
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57
lib/Target/XCore/XCoreFrameLowering.cpp
View File

@ -116,9 +116,9 @@ void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
}
bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(MF);
bool saveLR = XFI->getUsesLR();
// Do we need to allocate space on the stack?
if (FrameSize) {
bool saveLR = XFI->getUsesLR();
bool LRSavedOnEntry = false;
int Opcode;
if (saveLR && (MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0)) {
@ -148,18 +148,18 @@ void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
Moves.push_back(MachineMove(FrameLabel, CSDst, CSSrc));
}
}
if (saveLR) {
int LRSpillOffset = MFI->getObjectOffset(XFI->getLRSpillSlot());
storeToStack(MBB, MBBI, XCore::LR, LRSpillOffset + FrameSize*4, dl, TII);
MBB.addLiveIn(XCore::LR);
}
if (saveLR) {
int LRSpillOffset = MFI->getObjectOffset(XFI->getLRSpillSlot());
storeToStack(MBB, MBBI, XCore::LR, LRSpillOffset + FrameSize*4, dl, TII);
MBB.addLiveIn(XCore::LR);
if (emitFrameMoves) {
MCSymbol *SaveLRLabel = MMI->getContext().CreateTempSymbol();
BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(SaveLRLabel);
MachineLocation CSDst(MachineLocation::VirtualFP, LRSpillOffset);
MachineLocation CSSrc(XCore::LR);
MMI->getFrameMoves().push_back(MachineMove(SaveLRLabel, CSDst, CSSrc));
}
if (emitFrameMoves) {
MCSymbol *SaveLRLabel = MMI->getContext().CreateTempSymbol();
BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(SaveLRLabel);
MachineLocation CSDst(MachineLocation::VirtualFP, LRSpillOffset);
MachineLocation CSSrc(XCore::LR);
MMI->getFrameMoves().push_back(MachineMove(SaveLRLabel, CSDst, CSSrc));
}
}
@ -213,6 +213,7 @@ void XCoreFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
const XCoreInstrInfo &TII =
*static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
DebugLoc dl = MBBI->getDebugLoc();
bool FP = hasFP(MF);
@ -237,24 +238,26 @@ void XCoreFrameLowering::emitEpilogue(MachineFunction &MF,
report_fatal_error("emitEpilogue Frame size too big: " + Twine(FrameSize));
}
if (FrameSize) {
XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
if (FP) {
// Restore R10
int FPSpillOffset = MFI->getObjectOffset(XFI->getFPSpillSlot());
FPSpillOffset += FrameSize*4;
loadFromStack(MBB, MBBI, XCore::R10, FPSpillOffset, dl, TII);
}
if (FP) {
// Restore R10
int FPSpillOffset = MFI->getObjectOffset(XFI->getFPSpillSlot());
FPSpillOffset += FrameSize*4;
loadFromStack(MBB, MBBI, XCore::R10, FPSpillOffset, dl, TII);
}
bool restoreLR = XFI->getUsesLR();
if (restoreLR && MFI->getObjectOffset(XFI->getLRSpillSlot()) != 0) {
int LRSpillOffset = MFI->getObjectOffset(XFI->getLRSpillSlot());
LRSpillOffset += FrameSize*4;
loadFromStack(MBB, MBBI, XCore::LR, LRSpillOffset, dl, TII);
restoreLR = false;
}
bool restoreLR = XFI->getUsesLR();
if (restoreLR &&
(FrameSize == 0 || MFI->getObjectOffset(XFI->getLRSpillSlot()) != 0)) {
int LRSpillOffset = MFI->getObjectOffset(XFI->getLRSpillSlot());
LRSpillOffset += FrameSize*4;
loadFromStack(MBB, MBBI, XCore::LR, LRSpillOffset, dl, TII);
restoreLR = false;
}
if (FrameSize) {
if (restoreLR) {
// Fold prologue into return instruction
assert(MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0);
assert(MBBI->getOpcode() == XCore::RETSP_u6
|| MBBI->getOpcode() == XCore::RETSP_lu6);
int Opcode = (isU6) ? XCore::RETSP_u6 : XCore::RETSP_lu6;

11
test/CodeGen/XCore/epilogue_prologue.ll Normal file
View File

@ -0,0 +1,11 @@
; RUN: llc < %s -march=xcore | FileCheck %s
; CHECK: f1
; CHECK: stw lr, sp[0]
; CHECK: ldw lr, sp[0]
; CHECK-NEXT: retsp 0
define void @f1() nounwind {
entry:
tail call void asm sideeffect "", "~{lr}"() nounwind
ret void
}