diff options
Diffstat (limited to 'llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp index 21bfc91148bf..9f220ec003ec 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp @@ -1284,7 +1284,11 @@ Instruction *InstCombinerImpl::foldSelectValueEquivalence(SelectInst &Sel, isGuaranteedNotToBeUndefOrPoison(CmpRHS, SQ.AC, &Sel, &DT)) { if (Value *V = simplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, SQ, /* AllowRefinement */ true)) - return replaceOperand(Sel, Swapped ? 2 : 1, V); + // Require either the replacement or the simplification result to be a + // constant to avoid infinite loops. + // FIXME: Make this check more precise. + if (isa<Constant>(CmpRHS) || isa<Constant>(V)) + return replaceOperand(Sel, Swapped ? 2 : 1, V); // Even if TrueVal does not simplify, we can directly replace a use of // CmpLHS with CmpRHS, as long as the instruction is not used anywhere @@ -1302,7 +1306,8 @@ Instruction *InstCombinerImpl::foldSelectValueEquivalence(SelectInst &Sel, isGuaranteedNotToBeUndefOrPoison(CmpLHS, SQ.AC, &Sel, &DT)) if (Value *V = simplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, SQ, /* AllowRefinement */ true)) - return replaceOperand(Sel, Swapped ? 2 : 1, V); + if (isa<Constant>(CmpLHS) || isa<Constant>(V)) + return replaceOperand(Sel, Swapped ? 2 : 1, V); auto *FalseInst = dyn_cast<Instruction>(FalseVal); if (!FalseInst) |