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Simplify the tracking of virtual frame index registers. Ranges cannot overlap,
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
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@ -727,6 +727,9 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) {
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}
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}
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/// scavengeFrameVirtualRegs - Replace all frame index virtual registers
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/// with physical registers. Use the register scavenger to find an
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/// appropriate register to use.
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void PEI::scavengeFrameVirtualRegs(MachineFunction &Fn) {
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const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
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@ -735,33 +738,41 @@ void PEI::scavengeFrameVirtualRegs(MachineFunction &Fn) {
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E = Fn.end(); BB != E; ++BB) {
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RS->enterBasicBlock(BB);
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// Keep a map of which scratch reg we use for each virtual reg.
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// FIXME: Is a map like this the best solution? Seems like overkill,
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// but to get rid of it would need some fairly strong assumptions
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// that may not be valid as this gets smarter about reuse and such.
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IndexedMap<unsigned, VirtReg2IndexFunctor> ScratchRegForVirtReg;
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ScratchRegForVirtReg.grow(Fn.getRegInfo().getLastVirtReg());
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unsigned CurrentVirtReg = 0;
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unsigned CurrentScratchReg;
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for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) {
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MachineInstr *MI = I;
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for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
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if (MI->getOperand(i).isReg()) {
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unsigned Reg = MI->getOperand(i).getReg();
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if (Reg && TRI->isVirtualRegister(Reg)) {
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// If we already have a scratch for this virtual register, use it
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unsigned NewReg = ScratchRegForVirtReg[Reg];
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if (!NewReg) {
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const TargetRegisterClass *RC = Fn.getRegInfo().getRegClass(Reg);
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NewReg = RS->FindUnusedReg(RC);
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if (NewReg == 0)
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// No register is "free". Scavenge a register.
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// FIXME: Track SPAdj. Zero won't always be right
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NewReg = RS->scavengeRegister(RC, I, 0);
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assert (NewReg && "unable to scavenge register!");
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ScratchRegForVirtReg[Reg] = NewReg;
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}
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MI->getOperand(i).setReg(NewReg);
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if (Reg == 0 || !TRI->isVirtualRegister(Reg))
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continue;
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// If we already have a scratch for this virtual register, use it
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if (Reg != CurrentVirtReg) {
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// When we first encounter a new virtual register, it
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// must be a definition.
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assert(MI->getOperand(i).isDef() &&
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"frame index virtual missing def!");
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// We can't have nested virtual register live ranges because
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// there's only a guarantee of one scavenged register at a time.
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assert (CurrentVirtReg == 0 &&
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"overlapping frame index virtual registers!");
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CurrentVirtReg = Reg;
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const TargetRegisterClass *RC = Fn.getRegInfo().getRegClass(Reg);
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CurrentScratchReg = RS->FindUnusedReg(RC);
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if (CurrentScratchReg == 0)
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// No register is "free". Scavenge a register.
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// FIXME: Track SPAdj. Zero won't always be right
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CurrentScratchReg = RS->scavengeRegister(RC, I, 0);
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}
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assert (CurrentScratchReg && "Missing scratch register!");
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MI->getOperand(i).setReg(CurrentScratchReg);
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// If this is the last use of the register, stop tracking it.
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if (MI->getOperand(i).isKill())
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CurrentVirtReg = 0;
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}
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RS->forward(MI);
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}
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