diff --git a/lib/Target/X86/X86ISelDAGToDAG.cpp b/lib/Target/X86/X86ISelDAGToDAG.cpp index 853ac114dfe..9b7808eaa77 100644 --- a/lib/Target/X86/X86ISelDAGToDAG.cpp +++ b/lib/Target/X86/X86ISelDAGToDAG.cpp @@ -681,6 +681,11 @@ bool X86DAGToDAGISel::MatchAddress(SDOperand N, X86ISelAddressMode &AM, } break; + case ISD::SMUL_LOHI: + case ISD::UMUL_LOHI: + // A mul_lohi where we need the low part can be folded as a plain multiply. + if (N.ResNo != 0) break; + // FALL THROUGH case ISD::MUL: // X*[3,5,9] -> X+X*[2,4,8] if (!Available && diff --git a/test/CodeGen/X86/fold-mul-lohi.ll b/test/CodeGen/X86/fold-mul-lohi.ll new file mode 100644 index 00000000000..abd8ddd92c1 --- /dev/null +++ b/test/CodeGen/X86/fold-mul-lohi.ll @@ -0,0 +1,30 @@ +; RUN: llvm-as < %s | llc -march=x86 | not grep lea +; RUN: llvm-as < %s | llc -march=x86-64 | not grep lea + +@B = external global [1000 x i8], align 32 +@A = external global [1000 x i8], align 32 +@P = external global [1000 x i8], align 32 + +define void @foo(i32 %m) { +entry: + %tmp1 = icmp sgt i32 %m, 0 + br i1 %tmp1, label %bb, label %return + +bb: + %i.019.0 = phi i32 [ %indvar.next, %bb ], [ 0, %entry ] + %tmp2 = getelementptr [1000 x i8]* @B, i32 0, i32 %i.019.0 + %tmp3 = load i8* %tmp2, align 4 + %tmp4 = mul i8 %tmp3, 2 + %tmp5 = getelementptr [1000 x i8]* @A, i32 0, i32 %i.019.0 + store i8 %tmp4, i8* %tmp5, align 4 + %tmp8 = mul i32 %i.019.0, 9 + %tmp10 = getelementptr [1000 x i8]* @P, i32 0, i32 %tmp8 + store i8 17, i8* %tmp10, align 4 + %indvar.next = add i32 %i.019.0, 1 + %exitcond = icmp eq i32 %indvar.next, %m + br i1 %exitcond, label %return, label %bb + +return: + ret void +} +