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Transform (x&C)>V into (x&C)!=0 where possible

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When the least bit of C is greater than V, (x&C) must be greater than V
if it is not zero, so the comparison can be simplified.

Although this was suggested in Target/X86/README.txt, it benefits any
architecture with a directly testable form of AND.

Patch by Kevin Schoedel


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170576 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Paul Redmond
2012-12-19 19:47:13 +00:00
parent 433cb080ba
commit 6da2e22dff
3 changed files with 27 additions and 37 deletions
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17
test/Transforms/InstCombine/icmp.ll
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@@ -677,3 +677,20 @@ define i1 @test66(i64 %A, i64 %B) {
; CHECK-NEXT: ret i1 true
ret i1 %cmp
}
; CHECK: @test67
; CHECK: %and = and i32 %x, 96
; CHECK: %cmp = icmp ne i32 %and, 0
define i1 @test67(i32 %x) nounwind uwtable {
%and = and i32 %x, 127
%cmp = icmp sgt i32 %and, 31
ret i1 %cmp
}
; CHECK: @test68
; CHECK: %cmp = icmp ugt i32 %and, 30
define i1 @test68(i32 %x) nounwind uwtable {
%and = and i32 %x, 127
%cmp = icmp sgt i32 %and, 30
ret i1 %cmp
}