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Simplify the tracking of virtual frame index registers. Ranges cannot overlap,

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so a simple "current register" will suffice. Also add some additional
sanity-checking assertions to make sure things are as we expect.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83081 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jim Grosbach 2009-09-29 18:23:15 +00:00
parent 9ab2238df9
commit 9a0b6e6ded
1 changed files with 31 additions and 20 deletions
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51
lib/CodeGen/PrologEpilogInserter.cpp
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@ -727,6 +727,9 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) {
}
}
/// scavengeFrameVirtualRegs - Replace all frame index virtual registers
/// with physical registers. Use the register scavenger to find an
/// appropriate register to use.
void PEI::scavengeFrameVirtualRegs(MachineFunction &Fn) {
const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
@ -735,33 +738,41 @@ void PEI::scavengeFrameVirtualRegs(MachineFunction &Fn) {
E = Fn.end(); BB != E; ++BB) {
RS->enterBasicBlock(BB);
// Keep a map of which scratch reg we use for each virtual reg.
// FIXME: Is a map like this the best solution? Seems like overkill,
// but to get rid of it would need some fairly strong assumptions
// that may not be valid as this gets smarter about reuse and such.
IndexedMap<unsigned, VirtReg2IndexFunctor> ScratchRegForVirtReg;
ScratchRegForVirtReg.grow(Fn.getRegInfo().getLastVirtReg());
unsigned CurrentVirtReg = 0;
unsigned CurrentScratchReg;
for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) {
MachineInstr *MI = I;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
if (MI->getOperand(i).isReg()) {
unsigned Reg = MI->getOperand(i).getReg();
if (Reg && TRI->isVirtualRegister(Reg)) {
// If we already have a scratch for this virtual register, use it
unsigned NewReg = ScratchRegForVirtReg[Reg];
if (!NewReg) {
const TargetRegisterClass *RC = Fn.getRegInfo().getRegClass(Reg);
NewReg = RS->FindUnusedReg(RC);
if (NewReg == 0)
// No register is "free". Scavenge a register.
// FIXME: Track SPAdj. Zero won't always be right
NewReg = RS->scavengeRegister(RC, I, 0);
assert (NewReg && "unable to scavenge register!");
ScratchRegForVirtReg[Reg] = NewReg;
}
MI->getOperand(i).setReg(NewReg);
if (Reg == 0 || !TRI->isVirtualRegister(Reg))
continue;
// If we already have a scratch for this virtual register, use it
if (Reg != CurrentVirtReg) {
// When we first encounter a new virtual register, it
// must be a definition.
assert(MI->getOperand(i).isDef() &&
"frame index virtual missing def!");
// We can't have nested virtual register live ranges because
// there's only a guarantee of one scavenged register at a time.
assert (CurrentVirtReg == 0 &&
"overlapping frame index virtual registers!");
CurrentVirtReg = Reg;
const TargetRegisterClass *RC = Fn.getRegInfo().getRegClass(Reg);
CurrentScratchReg = RS->FindUnusedReg(RC);
if (CurrentScratchReg == 0)
// No register is "free". Scavenge a register.
// FIXME: Track SPAdj. Zero won't always be right
CurrentScratchReg = RS->scavengeRegister(RC, I, 0);
}
assert (CurrentScratchReg && "Missing scratch register!");
MI->getOperand(i).setReg(CurrentScratchReg);
// If this is the last use of the register, stop tracking it.
if (MI->getOperand(i).isKill())
CurrentVirtReg = 0;
}
RS->forward(MI);
}