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llvm-mirror/test/Transforms/InstCombine/bitreverse-fold.ll
James Molloy c1250c50be [InstCombine] Add trivial folding (bitreverse (bitreverse x)) -> x
There are plenty more instcombines we could probably do with bitreverse, but this seems like a very obvious and trivial starting point and was brought up by Hal in his review.

llvm-svn: 252879
2015-11-12 12:39:41 +00:00

12 lines
276 B
LLVM

; RUN: opt < %s -instcombine -S | FileCheck %s
define i32 @test1(i32 %p) {
; CHECK-LABEL: @test1
; CHECK-NEXT: ret i32 %p
%a = call i32 @llvm.bitreverse.i32(i32 %p)
%b = call i32 @llvm.bitreverse.i32(i32 %a)
ret i32 %b
}
declare i32 @llvm.bitreverse.i32(i32) readnone