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421fa9e32e
1) have it fold "br undef", which does occur with
surprising frequency as jump threading iterates.
2) teach j-t to delete dead blocks. This removes the successor
edges, reducing the in-edges of other blocks, allowing
recursive simplification.
3) Fold things like:
br COND, BBX, BBY
BBX:
br COND, BBZ, BBW
which also happens because jump threading iterates.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60470 91177308-0d34-0410-b5e6-96231b3b80d8
54 lines
911 B
LLVM
54 lines
911 B
LLVM
; RUN: llvm-as < %s | opt -jump-threading -simplifycfg -mem2reg | llvm-dis | grep {ret i32 %v1}
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; There should be no uncond branches left.
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; RUN: llvm-as < %s | opt -jump-threading -simplifycfg -mem2reg | llvm-dis | not grep {br label}
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declare i32 @f1()
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declare i32 @f2()
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declare void @f3()
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define i32 @test(i1 %cond) {
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br i1 %cond, label %T1, label %F1
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T1:
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%v1 = call i32 @f1()
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br label %Merge
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F1:
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%v2 = call i32 @f2()
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br label %Merge
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Merge:
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%A = phi i1 [true, %T1], [false, %F1]
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%B = phi i32 [%v1, %T1], [%v2, %F1]
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br i1 %A, label %T2, label %F2
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T2:
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call void @f3()
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ret i32 %B
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F2:
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ret i32 %B
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}
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;; cond is known false on Entry -> F1 edge!
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define i32 @test2(i1 %cond) {
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Entry:
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br i1 %cond, label %T1, label %F1
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T1:
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%v1 = call i32 @f1()
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br label %Merge
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F1:
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br i1 %cond, label %Merge, label %F2
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Merge:
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%B = phi i32 [47, %T1], [192, %F1]
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ret i32 %B
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F2:
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call void @f3()
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ret i32 12
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}
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