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increase the accuracy of register pressure computation in the presence of dead definitions by using live intervals, if available, to identify dead definitions and proceed accordingly.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194286 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Pedro Artigas
2013-11-08 22:46:28 +00:00
parent dc7eb3e023
commit d900b11795
2 changed files with 36 additions and 16 deletions
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33
lib/CodeGen/RegisterPressure.cpp
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@@ -498,10 +498,20 @@ bool RegPressureTracker::recede(SmallVectorImpl<unsigned> *LiveUses,
// TODO: consider earlyclobbers?
for (unsigned i = 0, e = RegOpers.Defs.size(); i < e; ++i) {
unsigned Reg = RegOpers.Defs[i];
if (LiveRegs.erase(Reg))
decreaseRegPressure(Reg);
else
discoverLiveOut(Reg);
bool DeadDef = false;
if (RequireIntervals) {
const LiveRange *LR = getLiveRange(Reg);
if (LR) {
LiveQueryResult LRQ = LR->Query(SlotIdx);
DeadDef = LRQ.isDeadDef();
}
}
if (!DeadDef) {
if (LiveRegs.erase(Reg))
decreaseRegPressure(Reg);
else
discoverLiveOut(Reg);
}
}
// Generate liveness for uses.
@@ -702,8 +712,19 @@ void RegPressureTracker::bumpUpwardPressure(const MachineInstr *MI) {
// Kill liveness at live defs.
for (unsigned i = 0, e = RegOpers.Defs.size(); i < e; ++i) {
unsigned Reg = RegOpers.Defs[i];
if (!containsReg(RegOpers.Uses, Reg))
decreaseRegPressure(Reg);
bool DeadDef = false;
if (RequireIntervals) {
const LiveRange *LR = getLiveRange(Reg);
if (LR) {
SlotIndex SlotIdx = LIS->getInstructionIndex(MI);
LiveQueryResult LRQ = LR->Query(SlotIdx);
DeadDef = LRQ.isDeadDef();
}
}
if (!DeadDef) {
if (!containsReg(RegOpers.Uses, Reg))
decreaseRegPressure(Reg);
}
}
// Generate liveness for uses.
for (unsigned i = 0, e = RegOpers.Uses.size(); i < e; ++i) {