1; RUN: opt -S -instcombine < %s | FileCheck %s 2target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32" 3target triple = "i386-apple-darwin10.0.0" 4 5; CHECK-LABEL: define void @fu1( 6define void @fu1(i32 %parm) nounwind ssp { 7 %1 = alloca i32, align 4 8; CHECK: alloca double* 9 %ptr = alloca double*, align 4 10 store i32 %parm, i32* %1, align 4 11 store double* null, double** %ptr, align 4 12 %2 = load i32, i32* %1, align 4 13 %3 = icmp ne i32 %2, 0 14 br i1 %3, label %4, label %10 15 16; <label>:4 ; preds = %0 17 %5 = load i32, i32* %1, align 4 18 %6 = shl nsw i32 %5, 3 19; With "nsw", the alloca and its bitcast can be fused: 20 %7 = add nsw i32 %6, 2048 21; CHECK: alloca double 22 %8 = alloca i8, i32 %7 23 %9 = bitcast i8* %8 to double* 24; CHECK-NEXT: store double* 25 store double* %9, double** %ptr, align 4 26 br label %10 27; <label>:10 ; preds = %4, %0 28 %11 = load double*, double** %ptr, align 4 29 call void @bar(double* %11) 30; CHECK: ret 31 ret void 32} 33 34declare void @bar(double*) 35 36; CHECK-LABEL: define void @fu2( 37define void @fu2(i32 %parm) nounwind ssp { 38 %1 = alloca i32, align 4 39 %ptr = alloca double*, align 4 40 store i32 %parm, i32* %1, align 4 41 store double* null, double** %ptr, align 4 42 %2 = load i32, i32* %1, align 4 43 %3 = icmp ne i32 %2, 0 44 br i1 %3, label %4, label %10 45 46; <label>:4 ; preds = %0 47 %5 = load i32, i32* %1, align 4 48 %6 = mul nsw i32 %5, 8 49; Without "nsw", the alloca and its bitcast cannot be fused: 50 %7 = add i32 %6, 2048 51; CHECK: alloca i8 52 %8 = alloca i8, i32 %7 53; CHECK-NEXT: bitcast double** 54; CHECK-NEXT: store i8* 55 %9 = bitcast i8* %8 to double* 56 store double* %9, double** %ptr, align 4 57 br label %10 58 59; <label>:10 ; preds = %4, %0 60 %11 = load double*, double** %ptr, align 4 61 call void @bar(double* %11) 62 ret void 63} 64 65