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f1474e1761
Use the presence of NSW/NUW to fold "icmp (x+cst), x" to a constant in cases where it would otherwise be undefined behavior. Surprisingly (to me at least), this triggers hundreds of the times in a few benchmarks: lencode, ldecode, and 466.h264ref seem to *really* like this. llvm-svn: 91812
115 lines
2.2 KiB
LLVM
115 lines
2.2 KiB
LLVM
; RUN: opt < %s -instcombine -S | FileCheck %s
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define i32 @test1(i32 %X) {
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entry:
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icmp slt i32 %X, 0 ; <i1>:0 [#uses=1]
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zext i1 %0 to i32 ; <i32>:1 [#uses=1]
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ret i32 %1
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; CHECK: @test1
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; CHECK: lshr i32 %X, 31
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; CHECK-NEXT: ret i32
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}
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define i32 @test2(i32 %X) {
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entry:
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icmp ult i32 %X, -2147483648 ; <i1>:0 [#uses=1]
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zext i1 %0 to i32 ; <i32>:1 [#uses=1]
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ret i32 %1
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; CHECK: @test2
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; CHECK: lshr i32 %X, 31
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; CHECK-NEXT: xor i32
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; CHECK-NEXT: ret i32
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}
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define i32 @test3(i32 %X) {
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entry:
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icmp slt i32 %X, 0 ; <i1>:0 [#uses=1]
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sext i1 %0 to i32 ; <i32>:1 [#uses=1]
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ret i32 %1
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; CHECK: @test3
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; CHECK: ashr i32 %X, 31
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; CHECK-NEXT: ret i32
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}
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define i32 @test4(i32 %X) {
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entry:
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icmp ult i32 %X, -2147483648 ; <i1>:0 [#uses=1]
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sext i1 %0 to i32 ; <i32>:1 [#uses=1]
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ret i32 %1
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; CHECK: @test4
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; CHECK: ashr i32 %X, 31
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; CHECK-NEXT: xor i32
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; CHECK-NEXT: ret i32
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}
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; PR4837
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define <2 x i1> @test5(<2 x i64> %x) {
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entry:
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%V = icmp eq <2 x i64> %x, undef
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ret <2 x i1> %V
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; CHECK: @test5
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; CHECK: ret <2 x i1> undef
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}
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define i32 @test6(i32 %a, i32 %b) {
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%c = icmp sle i32 %a, -1
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%d = zext i1 %c to i32
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%e = sub i32 0, %d
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%f = and i32 %e, %b
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ret i32 %f
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; CHECK: @test6
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; CHECK-NEXT: ashr i32 %a, 31
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; CHECK-NEXT: %f = and i32 %e, %b
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; CHECK-NEXT: ret i32 %f
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}
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define i1 @test7(i32 %x) {
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entry:
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%a = add i32 %x, -1
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%b = icmp ult i32 %a, %x
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ret i1 %b
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; CHECK: @test7
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; CHECK: %b = icmp ne i32 %x, 0
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; CHECK: ret i1 %b
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}
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define i1 @test8(i32 %x){
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entry:
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%a = add i32 %x, -1
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%b = icmp eq i32 %a, %x
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ret i1 %b
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; CHECK: @test8
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; CHECK: ret i1 false
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}
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define i1 @test9(i32 %x) {
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entry:
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%a = add i32 %x, -2
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%b = icmp ugt i32 %x, %a
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ret i1 %b
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; CHECK: @test9
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; CHECK: icmp ugt i32 %x, 1
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; CHECK: ret i1 %b
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}
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define i1 @test10(i32 %x){
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entry:
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%a = add i32 %x, -1
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%b = icmp slt i32 %a, %x
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ret i1 %b
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; CHECK: @test10
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; CHECK: %b = icmp ne i32 %x, -2147483648
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; CHECK: ret i1 %b
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}
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define i1 @test11(i32 %x) {
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%a = add nsw i32 %x, 8
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%b = icmp slt i32 %x, %a
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ret i1 %b
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; CHECK: @test11
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; CHECK: ret i1 true
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}
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