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108 lines
2.1 KiB
108 lines
2.1 KiB
; RUN: opt -early-cse -S < %s | FileCheck %s
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; Can we CSE a known condition to a constant?
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define i1 @test(i8* %p) {
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; CHECK-LABEL: @test
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entry:
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%cnd1 = icmp eq i8* %p, null
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br i1 %cnd1, label %taken, label %untaken
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taken:
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; CHECK-LABEL: taken:
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; CHECK-NEXT: ret i1 true
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%cnd2 = icmp eq i8* %p, null
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ret i1 %cnd2
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untaken:
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; CHECK-LABEL: untaken:
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; CHECK-NEXT: ret i1 false
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%cnd3 = icmp eq i8* %p, null
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ret i1 %cnd3
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}
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; We can CSE the condition, but we *don't* know it's value after the merge
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define i1 @test_neg1(i8* %p) {
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; CHECK-LABEL: @test_neg1
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entry:
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%cnd1 = icmp eq i8* %p, null
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br i1 %cnd1, label %taken, label %untaken
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taken:
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br label %merge
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untaken:
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br label %merge
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merge:
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; CHECK-LABEL: merge:
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; CHECK-NEXT: ret i1 %cnd1
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%cnd3 = icmp eq i8* %p, null
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ret i1 %cnd3
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}
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; Check specifically for a case where we have a unique predecessor, but
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; not a single predecessor. We can not know the value of the condition here.
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define i1 @test_neg2(i8* %p) {
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; CHECK-LABEL: @test_neg2
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entry:
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%cnd1 = icmp eq i8* %p, null
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br i1 %cnd1, label %merge, label %merge
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merge:
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; CHECK-LABEL: merge:
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; CHECK-NEXT: ret i1 %cnd1
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%cnd3 = icmp eq i8* %p, null
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ret i1 %cnd3
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}
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; Replace a use rather than CSE
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define i1 @test2(i8* %p) {
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; CHECK-LABEL: @test2
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entry:
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%cnd = icmp eq i8* %p, null
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br i1 %cnd, label %taken, label %untaken
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taken:
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; CHECK-LABEL: taken:
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; CHECK-NEXT: ret i1 true
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ret i1 %cnd
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untaken:
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; CHECK-LABEL: untaken:
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; CHECK-NEXT: ret i1 false
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ret i1 %cnd
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}
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; Not legal to replace use given it's not dominated by edge
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define i1 @test2_neg1(i8* %p) {
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; CHECK-LABEL: @test2_neg1
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entry:
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%cnd1 = icmp eq i8* %p, null
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br i1 %cnd1, label %taken, label %untaken
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taken:
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br label %merge
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untaken:
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br label %merge
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merge:
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; CHECK-LABEL: merge:
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; CHECK-NEXT: ret i1 %cnd1
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ret i1 %cnd1
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}
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; Another single predecessor test, but for dominated use
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define i1 @test2_neg2(i8* %p) {
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; CHECK-LABEL: @test2_neg2
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entry:
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%cnd1 = icmp eq i8* %p, null
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br i1 %cnd1, label %merge, label %merge
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merge:
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; CHECK-LABEL: merge:
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; CHECK-NEXT: ret i1 %cnd1
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ret i1 %cnd1
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}
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