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The support for remat of instructions with a register operand is hackish, to say the least. Since the register operand guaranteed to be PIC base and that it is already live at all uses, we are making sure it will not be spilled after its uses are rematerialized for both performance and correctness reasons.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48976 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2008-03-31 07:53:30 +00:00
parent 87a3b68bf7
commit 24d2f8a212
1 changed files with 7 additions and 18 deletions
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25
lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -886,15 +886,6 @@ rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
if (MI == ReMatOrigDefMI && CanDelete) {
DOUT << "\t\t\t\tErasing re-materlizable def: ";
DOUT << MI << '\n';
unsigned ImpUse = getReMatImplicitUse(li, MI);
if (ImpUse) {
// To be deleted MI has a virtual register operand, update the
// spill weight of the register interval.
unsigned loopDepth = loopInfo->getLoopDepth(MI->getParent());
LiveInterval &ImpLi = getInterval(ImpUse);
ImpLi.weight -=
getSpillWeight(false, true, loopDepth) / ImpLi.getSize();
}
RemoveMachineInstrFromMaps(MI);
vrm.RemoveMachineInstrFromMaps(MI);
MI->eraseFromParent();
@ -1116,6 +1107,7 @@ rewriteInstructionsForSpills(const LiveInterval &li, bool TrySplit,
MachineInstr *MI = &(*ri);
MachineOperand &O = ri.getOperand();
++ri;
assert(!O.isImplicit() && "Spilling register that's used as implicit use?");
unsigned index = getInstructionIndex(MI);
if (index < start || index >= end)
continue;
@ -1147,11 +1139,10 @@ rewriteInstructionsForSpills(const LiveInterval &li, bool TrySplit,
if (ImpUse && MI != ReMatDefMI) {
// Re-matting an instruction with virtual register use. Update the
// register interval's spill weight.
unsigned loopDepth = loopInfo->getLoopDepth(MI->getParent());
// register interval's spill weight to HUGE_VALF to prevent it from
// being spilled.
LiveInterval &ImpLi = getInterval(ImpUse);
ImpLi.weight +=
getSpillWeight(false, true, loopDepth) * NumUses / ImpLi.getSize();
ImpLi.weight = HUGE_VALF;
}
unsigned MBBId = MBB->getNumber();
@ -1575,12 +1566,10 @@ addIntervalsForSpills(const LiveInterval &li,
if (ImpUse) {
// Re-matting an instruction with virtual register use. Add the
// register as an implicit use on the use MI and update the register
// interval's spill weight.
unsigned loopDepth = loopInfo->getLoopDepth(MI->getParent());
// interval's spill weight to HUGE_VALF to prevent it from being
// spilled.
LiveInterval &ImpLi = getInterval(ImpUse);
ImpLi.weight +=
getSpillWeight(false, true, loopDepth) / ImpLi.getSize();
ImpLi.weight = HUGE_VALF;
MI->addOperand(MachineOperand::CreateReg(ImpUse, false, true));
}
}