Author: resistor
Date: Tue Aug 14 13:33:27 2007
New Revision: 41081
URL: http://llvm.org/viewvc/llvm-project?rev=41081&view=rev
Log:
Eliminate PHI nodes with constant values during normal GVN processing, even when
they're not related to eliminating a load.
Modified:
llvm/trunk/lib/Transforms/Scalar/GVN.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/GVN.cpp?rev=41081&r1=41080&r2=41081&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp Tue Aug 14 13:33:27 2007
@@ -946,7 +946,27 @@
unsigned num = VN.lookup_or_add(I);
- if (currAvail.test(num)) {
+ if (PHINode* p = dyn_cast<PHINode>(I)) {
+ Value* constVal = p->hasConstantValue();
+
+ if (constVal) {
+ if (Instruction* inst = dyn_cast<Instruction>(constVal)) {
+ DominatorTree &DT = getAnalysis<DominatorTree>();
+ if (DT.dominates(inst, p)) {
+ for (PhiMapType::iterator PI = phiMap.begin(), PE = phiMap.end();
+ PI != PE; ++PI)
+ if (PI->second.count(p))
+ PI->second.erase(p);
+
+ p->replaceAllUsesWith(inst);
+ toErase.push_back(p);
+ }
+ } else {
+ p->replaceAllUsesWith(constVal);
+ toErase.push_back(p);
+ }
+ }
+ } else if (currAvail.test(num)) {
Value* repl = find_leader(currAvail, num);
VN.erase(I);
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