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94327af5e1
isKnownNonEqual(A, B) returns true if it can be determined that A != B. At the moment it only knows two facts, that a non-wrapping add of nonzero to a value cannot be that value: A + B != A [where B != 0, addition is nsw or nuw] and that contradictory known bits imply two values are not equal. This patch also hooks this up to InstSimplify; InstSimplify had a peephole for the first fact but not the second so this teaches InstSimplify a new trick too (alas no measured performance impact!) llvm-svn: 251012
22 lines
526 B
LLVM
22 lines
526 B
LLVM
; RUN: opt -instsimplify < %s -S | FileCheck %s
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; CHECK: define i1 @test
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define i1 @test(i8* %pq, i8 %B) {
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%q = load i8, i8* %pq, !range !0 ; %q is known nonzero; no known bits
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%A = add nsw i8 %B, %q
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%cmp = icmp eq i8 %A, %B
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; CHECK: ret i1 false
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ret i1 %cmp
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}
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; CHECK: define i1 @test2
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define i1 @test2(i8 %a, i8 %b) {
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%A = or i8 %a, 2 ; %A[1] = 1
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%B = and i8 %b, -3 ; %B[1] = 0
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%cmp = icmp eq i8 %A, %B ; %A[1] and %B[1] are contradictory.
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; CHECK: ret i1 false
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ret i1 %cmp
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}
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!0 = !{ i8 1, i8 5 }
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