diff options
Diffstat (limited to 'lib/Transforms/Scalar/GVN.cpp')
-rw-r--r-- | lib/Transforms/Scalar/GVN.cpp | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp index cbfdbcddae..a51cbb631b 100644 --- a/lib/Transforms/Scalar/GVN.cpp +++ b/lib/Transforms/Scalar/GVN.cpp @@ -1935,10 +1935,15 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS, BasicBlock *Root) { // to 'LHS' then ensure it will be turned into 'RHS'. addToLeaderTable(VN.lookup_or_add(LHS), RHS, Root); - // Replace all occurrences of 'LHS' with 'RHS' everywhere in the scope. - unsigned NumReplacements = replaceAllDominatedUsesWith(LHS, RHS, Root); - bool Changed = NumReplacements > 0; - NumGVNEqProp += NumReplacements; + // Replace all occurrences of 'LHS' with 'RHS' everywhere in the scope. As + // LHS always has at least one use that is not dominated by Root, this will + // never do anything if LHS has only one use. + bool Changed = false; + if (!LHS->hasOneUse()) { + unsigned NumReplacements = replaceAllDominatedUsesWith(LHS, RHS, Root); + Changed |= NumReplacements > 0; + NumGVNEqProp += NumReplacements; + } // Now try to deduce additional equalities from this one. For example, if the // known equality was "(A != B)" == "false" then it follows that A and B are |