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We can prove that a 'sub' can be a 'sub nsw' under certain conditions: - The sign bits of the operands is the same. - Both operands have more than 1 sign bit. The subtraction cannot be a signed overflow in either case. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216037 91177308-0d34-0410-b5e6-96231b3b80d8
83 lines
2.4 KiB
LLVM
83 lines
2.4 KiB
LLVM
; Test that the strcmp library call simplifier works correctly.
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; RUN: opt < %s -instcombine -S | FileCheck %s
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target 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"
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@hello = constant [6 x i8] c"hello\00"
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@hell = constant [5 x i8] c"hell\00"
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@bell = constant [5 x i8] c"bell\00"
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@null = constant [1 x i8] zeroinitializer
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declare i32 @strcmp(i8*, i8*)
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; strcmp("", x) -> -*x
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define i32 @test1(i8* %str2) {
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; CHECK-LABEL: @test1(
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; CHECK: %strcmpload = load i8* %str
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; CHECK: %1 = zext i8 %strcmpload to i32
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; CHECK: %2 = sub nsw i32 0, %1
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; CHECK: ret i32 %2
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%str1 = getelementptr inbounds [1 x i8]* @null, i32 0, i32 0
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%temp1 = call i32 @strcmp(i8* %str1, i8* %str2)
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ret i32 %temp1
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}
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; strcmp(x, "") -> *x
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define i32 @test2(i8* %str1) {
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; CHECK-LABEL: @test2(
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; CHECK: %strcmpload = load i8* %str
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; CHECK: %1 = zext i8 %strcmpload to i32
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; CHECK: ret i32 %1
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%str2 = getelementptr inbounds [1 x i8]* @null, i32 0, i32 0
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%temp1 = call i32 @strcmp(i8* %str1, i8* %str2)
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ret i32 %temp1
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}
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; strcmp(x, y) -> cnst
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define i32 @test3() {
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; CHECK-LABEL: @test3(
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; CHECK: ret i32 -1
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%str1 = getelementptr inbounds [5 x i8]* @hell, i32 0, i32 0
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%str2 = getelementptr inbounds [6 x i8]* @hello, i32 0, i32 0
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%temp1 = call i32 @strcmp(i8* %str1, i8* %str2)
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ret i32 %temp1
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}
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define i32 @test4() {
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; CHECK-LABEL: @test4(
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; CHECK: ret i32 1
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%str1 = getelementptr inbounds [5 x i8]* @hell, i32 0, i32 0
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%str2 = getelementptr inbounds [1 x i8]* @null, i32 0, i32 0
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%temp1 = call i32 @strcmp(i8* %str1, i8* %str2)
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ret i32 %temp1
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}
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; strcmp(x, y) -> memcmp(x, y, <known length>)
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; (This transform is rather difficult to trigger in a useful manner)
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define i32 @test5(i1 %b) {
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; CHECK-LABEL: @test5(
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; CHECK: %memcmp = call i32 @memcmp(i8* getelementptr inbounds ([6 x i8]* @hello, i32 0, i32 0), i8* %str2, i32 5)
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; CHECK: ret i32 %memcmp
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%str1 = getelementptr inbounds [6 x i8]* @hello, i32 0, i32 0
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%temp1 = getelementptr inbounds [5 x i8]* @hell, i32 0, i32 0
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%temp2 = getelementptr inbounds [5 x i8]* @bell, i32 0, i32 0
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%str2 = select i1 %b, i8* %temp1, i8* %temp2
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%temp3 = call i32 @strcmp(i8* %str1, i8* %str2)
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ret i32 %temp3
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}
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; strcmp(x,x) -> 0
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define i32 @test6(i8* %str) {
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; CHECK-LABEL: @test6(
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; CHECK: ret i32 0
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%temp1 = call i32 @strcmp(i8* %str, i8* %str)
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ret i32 %temp1
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}
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