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If a PHI starts at a non-negative constant, monotonically increases (only adds of a constant are supported at the moment) and that add does not wrap, then the PHI is known never to be zero. llvm-svn: 248796
50 lines
1.0 KiB
LLVM
50 lines
1.0 KiB
LLVM
; RUN: opt -instsimplify -S < %s | FileCheck %s
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; CHECK-LABEL: @test1
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define i1 @test1(i8 %p, i8* %pq, i8 %n, i8 %r) {
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entry:
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br label %loop
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loop:
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%A = phi i8 [ 1, %entry ], [ %next, %loop ]
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%next = add nsw i8 %A, 1
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%cmp1 = icmp eq i8 %A, %n
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br i1 %cmp1, label %exit, label %loop
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exit:
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%add = or i8 %A, %r
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%cmp = icmp eq i8 %add, 0
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; CHECK: ret i1 false
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ret i1 %cmp
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}
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; CHECK-LABEL: @test2
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define i1 @test2(i8 %p, i8* %pq, i8 %n, i8 %r) {
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entry:
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br label %loop
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loop:
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%A = phi i8 [ 1, %entry ], [ %next, %loop ]
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%next = add i8 %A, 1
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%cmp1 = icmp eq i8 %A, %n
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br i1 %cmp1, label %exit, label %loop
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exit:
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%add = or i8 %A, %r
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%cmp = icmp eq i8 %add, 0
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; CHECK-NOT: ret i1 false
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ret i1 %cmp
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}
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; CHECK-LABEL: @test3
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define i1 @test3(i8 %p, i8* %pq, i8 %n, i8 %r) {
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entry:
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br label %loop
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loop:
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%A = phi i8 [ 1, %entry ], [ %next, %loop ]
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%next = add nuw i8 %A, 1
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%cmp1 = icmp eq i8 %A, %n
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br i1 %cmp1, label %exit, label %loop
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exit:
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%add = or i8 %A, %r
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%cmp = icmp eq i8 %add, 0
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; CHECK: ret i1 false
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ret i1 %cmp
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}
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