diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp | 6 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/fmul.ll | 13 |
2 files changed, 17 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp index a9e3e5f00f6..73172877d9e 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -374,11 +374,13 @@ Instruction *InstCombiner::visitFMul(BinaryOperator &I) { return BinaryOperator::CreateFMulFMF(X, ConstantExpr::getFNeg(C), &I); // Sink negation: -X * Y --> -(X * Y) - if (match(Op0, m_OneUse(m_FNeg(m_Value(X))))) + // But don't transform constant expressions because there's an inverse fold. + if (match(Op0, m_OneUse(m_FNeg(m_Value(X)))) && !isa<ConstantExpr>(Op0)) return BinaryOperator::CreateFNegFMF(Builder.CreateFMulFMF(X, Op1, &I), &I); // Sink negation: Y * -X --> -(X * Y) - if (match(Op1, m_OneUse(m_FNeg(m_Value(X))))) + // But don't transform constant expressions because there's an inverse fold. + if (match(Op1, m_OneUse(m_FNeg(m_Value(X)))) && !isa<ConstantExpr>(Op1)) return BinaryOperator::CreateFNegFMF(Builder.CreateFMulFMF(X, Op0, &I), &I); // fabs(X) * fabs(X) -> X * X diff --git a/llvm/test/Transforms/InstCombine/fmul.ll b/llvm/test/Transforms/InstCombine/fmul.ll index fcf0941c867..99b67dfa845 100644 --- a/llvm/test/Transforms/InstCombine/fmul.ll +++ b/llvm/test/Transforms/InstCombine/fmul.ll @@ -981,3 +981,16 @@ define float @fmul_fdiv_factor_extra_use(float %x, float %y) { %mul = fmul reassoc float %div, %y ret float %mul } + +; Avoid infinite looping by moving negation out of a constant expression. + +@g = external global {[2 x i8*]}, align 1 + +define double @fmul_negated_constant_expression(double %x) { +; CHECK-LABEL: @fmul_negated_constant_expression( +; CHECK-NEXT: [[R:%.*]] = fmul double [[X:%.*]], fsub (double -0.000000e+00, double bitcast (i64 ptrtoint (i8** getelementptr inbounds ({ [2 x i8*] }, { [2 x i8*] }* @g, i64 0, inrange i32 0, i64 2) to i64) to double)) +; CHECK-NEXT: ret double [[R]] +; + %r = fmul double %x, fsub (double -0.000000e+00, double bitcast (i64 ptrtoint (i8** getelementptr inbounds ({ [2 x i8*] }, { [2 x i8*] }* @g, i64 0, inrange i32 0, i64 2) to i64) to double)) + ret double %r +} |
