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e0134d95cc
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
73 lines
2.2 KiB
LLVM
73 lines
2.2 KiB
LLVM
; Test that the memcmp library call simplifier works correctly.
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;
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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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@foo = constant [4 x i8] c"foo\00"
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@hel = constant [4 x i8] c"hel\00"
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@hello_u = constant [8 x i8] c"hello_u\00"
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declare i32 @memcmp(i8*, i8*, i32)
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; Check memcmp(mem, mem, size) -> 0.
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define i32 @test_simplify1(i8* %mem, i32 %size) {
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; CHECK-LABEL: @test_simplify1(
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%ret = call i32 @memcmp(i8* %mem, i8* %mem, i32 %size)
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ret i32 %ret
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; CHECK: ret i32 0
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}
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; Check memcmp(mem1, mem2, 0) -> 0.
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define i32 @test_simplify2(i8* %mem1, i8* %mem2) {
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; CHECK-LABEL: @test_simplify2(
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%ret = call i32 @memcmp(i8* %mem1, i8* %mem2, i32 0)
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ret i32 %ret
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; CHECK: ret i32 0
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}
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;; Check memcmp(mem1, mem2, 1) -> *(unsigned char*)mem1 - *(unsigned char*)mem2.
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define i32 @test_simplify3(i8* %mem1, i8* %mem2) {
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; CHECK-LABEL: @test_simplify3(
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%ret = call i32 @memcmp(i8* %mem1, i8* %mem2, i32 1)
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; CHECK: [[LOAD1:%[a-z]+]] = load i8* %mem1, align 1
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; CHECK: [[ZEXT1:%[a-z]+]] = zext i8 [[LOAD1]] to i32
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; CHECK: [[LOAD2:%[a-z]+]] = load i8* %mem2, align 1
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; CHECK: [[ZEXT2:%[a-z]+]] = zext i8 [[LOAD2]] to i32
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; CHECK: [[RET:%[a-z]+]] = sub nsw i32 [[ZEXT1]], [[ZEXT2]]
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ret i32 %ret
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; CHECK: ret i32 [[RET]]
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}
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; Check memcmp(mem1, mem2, size) -> cnst, where all arguments are constants.
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define i32 @test_simplify4() {
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; CHECK-LABEL: @test_simplify4(
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%mem1 = getelementptr [4 x i8]* @hel, i32 0, i32 0
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%mem2 = getelementptr [8 x i8]* @hello_u, i32 0, i32 0
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%ret = call i32 @memcmp(i8* %mem1, i8* %mem2, i32 3)
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ret i32 %ret
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; CHECK: ret i32 0
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}
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define i32 @test_simplify5() {
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; CHECK-LABEL: @test_simplify5(
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%mem1 = getelementptr [4 x i8]* @hel, i32 0, i32 0
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%mem2 = getelementptr [4 x i8]* @foo, i32 0, i32 0
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%ret = call i32 @memcmp(i8* %mem1, i8* %mem2, i32 3)
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ret i32 %ret
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; CHECK: ret i32 1
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}
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define i32 @test_simplify6() {
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; CHECK-LABEL: @test_simplify6(
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%mem1 = getelementptr [4 x i8]* @foo, i32 0, i32 0
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%mem2 = getelementptr [4 x i8]* @hel, i32 0, i32 0
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%ret = call i32 @memcmp(i8* %mem1, i8* %mem2, i32 3)
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ret i32 %ret
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; CHECK: ret i32 -1
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}
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