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Search for a free FP register instead of just assuming FP7 is not in use.

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llvm-svn: 108535
This commit is contained in:
Jakob Stoklund Olesen 2010-07-16 17:41:40 +00:00
parent ca2a306a1a
commit 5fbe7d869c
1 changed files with 12 additions and 6 deletions
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18
lib/Target/X86/X86FloatingPoint.cpp
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@ -157,6 +157,14 @@ namespace {
return Slot < StackTop && Stack[Slot] == RegNo;
}
// getScratchReg - Return an FP register that is not currently in use.
unsigned getScratchReg() {
for (int i = 7; i >= 0; --i)
if (!isLive(i))
return i;
llvm_unreachable("Ran out of scratch FP registers");
}
// getStackEntry - Return the X86::FP<n> register in register ST(i).
unsigned getStackEntry(unsigned STi) const {
assert(STi < StackTop && "Access past stack top!");
@ -994,7 +1002,7 @@ void FPS::handleOneArgFP(MachineBasicBlock::iterator &I) {
MI->getOpcode() == X86::ISTT_Fp32m80 ||
MI->getOpcode() == X86::ISTT_Fp64m80 ||
MI->getOpcode() == X86::ST_FpP80m)) {
duplicateToTop(Reg, 7 /*temp register*/, I);
duplicateToTop(Reg, getScratchReg(), I);
} else {
moveToTop(Reg, I); // Move to the top of the stack...
}
@ -1347,8 +1355,7 @@ void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) {
if (!MI->killsRegister(X86::FP0 + Op0)) {
// Duplicate Op0 into a temporary on the stack top.
// This actually assumes that FP7 is dead.
duplicateToTop(Op0, 7, I);
duplicateToTop(Op0, getScratchReg(), I);
} else {
// Op0 is killed, so just swap it into position.
moveToTop(Op0, I);
@ -1368,8 +1375,7 @@ void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) {
++StackTop;
unsigned RegOnTop = getStackEntry(0); // This reg must remain in st(0).
if (!MI->killsRegister(X86::FP0 + Op0)) {
// Assume FP6 is not live, use it as a scratch register.
duplicateToTop(Op0, 6, I);
duplicateToTop(Op0, getScratchReg(), I);
moveToTop(RegOnTop, I);
} else if (getSTReg(Op0) != X86::ST1) {
// We have the wrong value at st(1). Shuffle! Untested!
@ -1513,7 +1519,7 @@ void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) {
// Duplicate the TOS so that we return it twice. Just pick some other FPx
// register to hold it.
unsigned NewReg = (FirstFPRegOp+1)%7;
unsigned NewReg = getScratchReg();
duplicateToTop(FirstFPRegOp, NewReg, MI);
FirstFPRegOp = NewReg;
}