diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp | 8 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/mul.ll | 16 |
2 files changed, 22 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp index 35513f1ed31..a554e9f628e 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -217,12 +217,16 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { NewCst = getLogBase2Vector(CV); if (NewCst) { + unsigned Width = NewCst->getType()->getPrimitiveSizeInBits(); BinaryOperator *Shl = BinaryOperator::CreateShl(NewOp, NewCst); if (I.hasNoUnsignedWrap()) Shl->setHasNoUnsignedWrap(); - if (I.hasNoSignedWrap() && NewCst->isNotMinSignedValue()) - Shl->setHasNoSignedWrap(); + if (I.hasNoSignedWrap()) { + uint64_t V; + if (match(NewCst, m_ConstantInt(V)) && V != Width - 1) + Shl->setHasNoSignedWrap(); + } return Shl; } diff --git a/llvm/test/Transforms/InstCombine/mul.ll b/llvm/test/Transforms/InstCombine/mul.ll index de09f129cdf..6e67c7fa08a 100644 --- a/llvm/test/Transforms/InstCombine/mul.ll +++ b/llvm/test/Transforms/InstCombine/mul.ll @@ -288,3 +288,19 @@ define i32 @test31(i32 %V) { ; CHECK: %[[mul:.*]] = shl i32 %V, zext (i1 icmp ne (i32* inttoptr (i64 1 to i32*), i32* @PR22087) to i32) ; CHECK-NEXT: ret i32 %[[mul]] } + +define i32 @test32(i32 %X) { +; CHECK-LABEL: @test32 + %mul = mul nsw i32 %X, -2147483648 + ret i32 %mul +; CHECK: %[[shl:.*]] = shl i32 %X, 31 +; CHECK-NEXT: ret i32 %[[shl]] +} + +define i32 @test33(i32 %X) { +; CHECK-LABEL: @test33 + %mul = mul nsw i32 %X, 1073741824 +; CHECK: %[[shl:.*]] = shl nsw i32 %X, 30 +; CHECK-NEXT: ret i32 %[[shl]] + ret i32 %mul +} |
