Make RecursivelyDeleteDeadPHINode delete a phi node that has no users and add a
test for that. With this change, test/CodeGen/X86/codegen-dce.ll no longer finds
any instructions to DCE, so delete the test.
Also renamed J and JP to I and IP in RecursivelyDeleteDeadPHINode.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126088 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index 063c76e..20d7989 100644
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -283,6 +283,11 @@
/// delete it. If that makes any of its operands trivially dead, delete them
/// too, recursively. Return true if the PHI node is actually deleted.
bool llvm::RecursivelyDeleteDeadPHINode(PHINode *PN) {
+ if (PN->use_empty()) {
+ PN->eraseFromParent();
+ return true;
+ }
+
// We can remove a PHI if it is on a cycle in the def-use graph
// where each node in the cycle has degree one, i.e. only one use,
// and is an instruction with no side effects.
@@ -292,16 +297,16 @@
bool Changed = false;
SmallPtrSet<PHINode *, 4> PHIs;
PHIs.insert(PN);
- for (Instruction *J = cast<Instruction>(*PN->use_begin());
- areAllUsesEqual(J) && !J->mayHaveSideEffects();
- J = cast<Instruction>(*J->use_begin()))
+ for (Instruction *I = cast<Instruction>(*PN->use_begin());
+ areAllUsesEqual(I) && !I->mayHaveSideEffects();
+ I = cast<Instruction>(*I->use_begin()))
// If we find a PHI more than once, we're on a cycle that
// won't prove fruitful.
- if (PHINode *JP = dyn_cast<PHINode>(J))
- if (!PHIs.insert(JP)) {
+ if (PHINode *IP = dyn_cast<PHINode>(I))
+ if (!PHIs.insert(IP)) {
// Break the cycle and delete the PHI and its operands.
- JP->replaceAllUsesWith(UndefValue::get(JP->getType()));
- (void)RecursivelyDeleteTriviallyDeadInstructions(JP);
+ IP->replaceAllUsesWith(UndefValue::get(IP->getType()));
+ (void)RecursivelyDeleteTriviallyDeadInstructions(IP);
Changed = true;
break;
}