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ca99cf7d94
This is a cleaned up patch from the one written by John Regehr based on the findings of the Souper superoptimizer. When writing tests, I was surprised to find that instsimplify apparently doesn't know how to collapse bit test sequences based purely on known bits. This required me to split my tests across both instsimplify and instcombine. Differential Revision: http://reviews.llvm.org/D13250 llvm-svn: 249453
48 lines
1.1 KiB
LLVM
48 lines
1.1 KiB
LLVM
; RUN: opt < %s -S -instcombine | FileCheck %s
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; Note: This is testing functionality in computeKnownBits. I'd have rather
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; used instsimplify, but the bit test folding is apparently only in instcombine.
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declare i16 @llvm.bswap.i16(i16)
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declare i32 @llvm.bswap.i32(i32)
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define i1 @test1(i16 %arg) {
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; CHECK-LABEL: @test1
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; CHECK: ret i1 true
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%a = or i16 %arg, 511
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%b = call i16 @llvm.bswap.i16(i16 %a)
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%and = and i16 %b, 256
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%res = icmp eq i16 %and, 256
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ret i1 %res
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}
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define i1 @test2(i16 %arg) {
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; CHECK-LABEL: @test2
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; CHECK: ret i1 true
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%a = or i16 %arg, 1
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%b = call i16 @llvm.bswap.i16(i16 %a)
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%and = and i16 %b, 256
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%res = icmp eq i16 %and, 256
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ret i1 %res
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}
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define i1 @test3(i16 %arg) {
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; CHECK-LABEL: @test3
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; CHECK: ret i1 true
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%a = or i16 %arg, 256
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%b = call i16 @llvm.bswap.i16(i16 %a)
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%and = and i16 %b, 1
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%res = icmp eq i16 %and, 1
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ret i1 %res
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}
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define i1 @test4(i32 %arg) {
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; CHECK-LABEL: @test4
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; CHECK: ret i1 true
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%a = or i32 %arg, 2147483647 ; i32_MAX
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%b = call i32 @llvm.bswap.i32(i32 %a)
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%and = and i32 %b, 127
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%res = icmp eq i32 %and, 127
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ret i1 %res
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}
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