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60d410d7bb
first, it can kick in on blocks whose conditions have been folded to a constant, even though one of the edges will be trivially folded. second, it doesn't clean up the "if diamond" that it just eliminated away. This is a problem because other simplifycfg xforms kick in depending on the order of block visitation, causing pointless work. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121762 91177308-0d34-0410-b5e6-96231b3b80d8
26 lines
749 B
LLVM
26 lines
749 B
LLVM
; Test merging of blocks that only have PHI nodes in them
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;
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; RUN: opt < %s -simplifycfg -S | FileCheck %s
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;
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define i32 @test(i1 %a, i1 %b) {
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; CHECK: br i1 %a
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br i1 %a, label %M, label %O
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O: ; preds = %0
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; CHECK: select i1 %b, i32 0, i32 1
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; CHECK-NOT: phi
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br i1 %b, label %N, label %Q
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Q: ; preds = %O
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br label %N
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N: ; preds = %Q, %O
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; This block should be foldable into M
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%Wp = phi i32 [ 0, %O ], [ 1, %Q ] ; <i32> [#uses=1]
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br label %M
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M: ; preds = %N, %0
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; CHECK: %W = phi i32
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%W = phi i32 [ %Wp, %N ], [ 2, %0 ] ; <i32> [#uses=1]
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%R = add i32 %W, 1 ; <i32> [#uses=1]
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ret i32 %R
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}
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