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70 lines
1.7 KiB
LLVM
70 lines
1.7 KiB
LLVM
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; RUN: opt -S -jump-threading %s | FileCheck %s
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; When simplify a branch based on LVI predicates, we should replace the
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; comparison itself with a constant (when possible) in case it's otherwise used.
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define i32 @test(i32* %p) {
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; CHECK-LABEL: @test
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; CHECK: icmp eq
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; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1
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; CHECK-NOT: icmp ne
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entry:
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%cmp = icmp eq i32* %p, null
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br i1 %cmp, label %is_null, label %not_null
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is_null:
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%cmp2 = icmp ne i32* %p, null
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br i1 %cmp2, label %exit1, label %exit2
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not_null:
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%cmp3 = icmp ne i32* %p, null
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br i1 %cmp3, label %exit1, label %exit2
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exit1:
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ret i32 0
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exit2:
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ret i32 1
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}
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declare void @use(i1)
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; It would not be legal to replace %cmp2 (well, in this case it actually is,
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; but that's a CSE problem, not a LVI/jump threading problem)
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define i32 @test_negative(i32* %p) {
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; CHECK-LABEL: @test
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; CHECK: icmp ne
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; CHECK: icmp eq
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; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1
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; CHECK-NOT: icmp ne
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entry:
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%cmp2 = icmp ne i32* %p, null
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call void @use(i1 %cmp2)
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%cmp = icmp eq i32* %p, null
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br i1 %cmp, label %is_null, label %not_null
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is_null:
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br i1 %cmp2, label %exit1, label %exit2
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not_null:
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br i1 %cmp2, label %exit1, label %exit2
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exit1:
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ret i32 0
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exit2:
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ret i32 1
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}
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; In this case, we can remove cmp2 because it's otherwise unused
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define i32 @test2(i32* %p) {
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; CHECK-LABEL: @test
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; CHECK-LABEL: entry:
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; CHECK-NEXT: icmp eq
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; CHECK-NEXT: br i1 %cmp, label %exit2, label %exit1
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; CHECK-NOT: icmp ne
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entry:
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%cmp2 = icmp ne i32* %p, null
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%cmp = icmp eq i32* %p, null
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br i1 %cmp, label %is_null, label %not_null
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is_null:
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br i1 %cmp2, label %exit1, label %exit2
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not_null:
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br i1 %cmp2, label %exit1, label %exit2
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exit1:
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ret i32 0
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exit2:
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ret i32 1
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}
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