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Leave hasPHIKill flags alone in LiveInterval::RenumberValues.

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It is conservatively correct to keep the hasPHIKill flags, even after
deleting PHI-defs.

The calculation can be very expensive after taildup has created a
quadratic number of indirectbr edges in the CFG, and the hasPHIKill flag
isn't used for anything after RenumberValues().

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139780 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2011-09-15 04:37:18 +00:00
parent f59c532cfd
commit 573a32d487
2 changed files with 0 additions and 22 deletions
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1
include/llvm/CodeGen/LiveInterval.h
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@ -313,7 +313,6 @@ namespace llvm {
/// RenumberValues - Renumber all values in order of appearance and remove
/// unused values.
/// Recalculate phi-kill flags in case any phi-def values were removed.
void RenumberValues(LiveIntervals &lis);
/// isOnlyLROfValNo - Return true if the specified live range is the only

21
lib/CodeGen/LiveInterval.cpp
View File

@ -148,7 +148,6 @@ void LiveInterval::markValNoForDeletion(VNInfo *ValNo) {
/// remaining unused values.
void LiveInterval::RenumberValues(LiveIntervals &lis) {
SmallPtrSet<VNInfo*, 8> Seen;
bool seenPHIDef = false;
valnos.clear();
for (const_iterator I = begin(), E = end(); I != E; ++I) {
VNInfo *VNI = I->valno;
@ -157,26 +156,6 @@ void LiveInterval::RenumberValues(LiveIntervals &lis) {
assert(!VNI->isUnused() && "Unused valno used by live range");
VNI->id = (unsigned)valnos.size();
valnos.push_back(VNI);
VNI->setHasPHIKill(false);
if (VNI->isPHIDef())
seenPHIDef = true;
}
// Recompute phi kill flags.
if (!seenPHIDef)
return;
for (const_vni_iterator I = vni_begin(), E = vni_end(); I != E; ++I) {
VNInfo *VNI = *I;
if (!VNI->isPHIDef())
continue;
const MachineBasicBlock *PHIBB = lis.getMBBFromIndex(VNI->def);
assert(PHIBB && "No basic block for phi-def");
for (MachineBasicBlock::const_pred_iterator PI = PHIBB->pred_begin(),
PE = PHIBB->pred_end(); PI != PE; ++PI) {
VNInfo *KVNI = getVNInfoAt(lis.getMBBEndIdx(*PI).getPrevSlot());
if (KVNI)
KVNI->setHasPHIKill(true);
}
}
}