diff options
| -rw-r--r-- | clang/lib/CodeGen/CGExprScalar.cpp | 20 | ||||
| -rw-r--r-- | clang/test/CodeGen/fp-contract-pragma.cpp | 12 |
2 files changed, 21 insertions, 11 deletions
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp index 59296a3c422..cb6432d037c 100644 --- a/clang/lib/CodeGen/CGExprScalar.cpp +++ b/clang/lib/CodeGen/CGExprScalar.cpp @@ -2564,19 +2564,17 @@ static Value* tryEmitFMulAdd(const BinOpInfo &op, return nullptr; // We have a potentially fusable op. Look for a mul on one of the operands. - if (llvm::BinaryOperator* LHSBinOp = dyn_cast<llvm::BinaryOperator>(op.LHS)) { - if (LHSBinOp->getOpcode() == llvm::Instruction::FMul) { - assert(LHSBinOp->getNumUses() == 0 && - "Operations with multiple uses shouldn't be contracted."); + // Also, make sure that the mul result isn't used directly. In that case, + // there's no point creating a muladd operation. + if (auto *LHSBinOp = dyn_cast<llvm::BinaryOperator>(op.LHS)) { + if (LHSBinOp->getOpcode() == llvm::Instruction::FMul && + LHSBinOp->use_empty()) return buildFMulAdd(LHSBinOp, op.RHS, CGF, Builder, false, isSub); - } - } else if (llvm::BinaryOperator* RHSBinOp = - dyn_cast<llvm::BinaryOperator>(op.RHS)) { - if (RHSBinOp->getOpcode() == llvm::Instruction::FMul) { - assert(RHSBinOp->getNumUses() == 0 && - "Operations with multiple uses shouldn't be contracted."); + } + if (auto *RHSBinOp = dyn_cast<llvm::BinaryOperator>(op.RHS)) { + if (RHSBinOp->getOpcode() == llvm::Instruction::FMul && + RHSBinOp->use_empty()) return buildFMulAdd(RHSBinOp, op.LHS, CGF, Builder, isSub, false); - } } return nullptr; diff --git a/clang/test/CodeGen/fp-contract-pragma.cpp b/clang/test/CodeGen/fp-contract-pragma.cpp index 86e236e4db5..1ea974f5fef 100644 --- a/clang/test/CodeGen/fp-contract-pragma.cpp +++ b/clang/test/CodeGen/fp-contract-pragma.cpp @@ -62,3 +62,15 @@ float fp_contract_6(float a, float b, float c) { return a * b + c; } +// If the multiply has multiple uses, don't produce fmuladd. +// This used to assert (PR25719): +// https://llvm.org/bugs/show_bug.cgi?id=25719 + +float fp_contract_7(float a, float b, float c) { +// CHECK: _Z13fp_contract_7fff +// CHECK: %mul = fmul float %b, 2.000000e+00 +// CHECK-NEXT: fsub float %mul, %c + #pragma STDC FP_CONTRACT ON + return (a = 2 * b) - c; +} + |
