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It has finally happened. Spiller is now using live interval info.

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This fixes a very subtle bug. vr defined by an implicit_def is allowed overlap with any register since it doesn't actually modify anything. However, if it's used as a two-address use, its live range can be extended and it can be spilled. The spiller must take care not to emit a reload for the vn number that's defined by the implicit_def. This is both a correctness and performance issue.

llvm-svn: 69743
This commit is contained in:
Evan Cheng
2009-04-21 22:46:52 +00:00
parent 41b8694777
commit 1a99a5f501
7 changed files with 95 additions and 42 deletions
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6
llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
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@@ -1304,7 +1304,7 @@ rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
// Update stack slot spill weight if we are splitting.
float Weight = getSpillWeight(HasDef, HasUse, loopDepth);
if (!TrySplit)
if (!TrySplit)
SSWeight += Weight;
// Create a new virtual register for the spill interval.
@@ -1338,7 +1338,7 @@ rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
HasUse = false;
HasDef = false;
CanFold = false;
if (isRemoved(MI)) {
if (isNotInMIMap(MI)) {
SSWeight -= Weight;
break;
}
@@ -1393,7 +1393,7 @@ rewriteInstructionForSpills(const LiveInterval &li, const VNInfo *VNI,
if (DefIsReMat && ImpUse)
MI->addOperand(MachineOperand::CreateReg(ImpUse, false, true));
// create a new register interval for this spill / remat.
// Create a new register interval for this spill / remat.
LiveInterval &nI = getOrCreateInterval(NewVReg);
if (CreatedNewVReg) {
NewLIs.push_back(&nI);