Fix a fixme in CondPropagate.cpp by moving a PhiNode optimization into
BasicBlock's removePredecessor routine. This requires shuffling around
the definition and implementation of hasContantValue from Utils.h,cpp into
Instructions.h,cpp
llvm-svn: 22664
diff --git a/llvm/lib/VMCore/BasicBlock.cpp b/llvm/lib/VMCore/BasicBlock.cpp
index 98d12d8..407080c 100644
--- a/llvm/lib/VMCore/BasicBlock.cpp
+++ b/llvm/lib/VMCore/BasicBlock.cpp
@@ -189,8 +189,16 @@
// Okay, now we know that we need to remove predecessor #pred_idx from all
// PHI nodes. Iterate over each PHI node fixing them up
PHINode *PN;
- for (iterator II = begin(); (PN = dyn_cast<PHINode>(II)); ++II)
+ for (iterator II = begin(); (PN = dyn_cast<PHINode>(II)); ++II) {
PN->removeIncomingValue(Pred, false);
+ // If all incoming values to the Phi are the same, we can replace the Phi
+ // with that value.
+ if (Value *PNV = PN->hasConstantValue())
+ if (!isa<Instruction>(PNV)) {
+ PN->replaceAllUsesWith(PNV);
+ PN->eraseFromParent();
+ }
+ }
}
}