ea5b72825b
Summary: Usually LCSSA survives this transformation, but in some cases (see attached test) it doesn't: values from the original loop after separating might be used from the outer loop. Before the transformation it was the same loop, so LCSSA phis were not required. This fixes PR28272. Reviewers: sanjoy, hfinkel, chandlerc Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D21665 llvm-svn: 275891
77 lines
1.6 KiB
LLVM
77 lines
1.6 KiB
LLVM
; RUN: opt < %s -lcssa -loop-unroll -S | FileCheck %s
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target triple = "x86_64-unknown-linux-gnu"
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; PR28272
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; When LoopSimplify separates nested loops, it might break LCSSA form: values
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; from the original loop might be used in the outer loop. This test invokes
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; loop-unroll, which calls loop-simplify before itself. If LCSSA is broken
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; after loop-simplify, we crash on assertion.
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; CHECK-LABEL: @foo
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define void @foo() {
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entry:
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br label %header
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header:
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br label %loop1
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loop1:
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br i1 true, label %loop1, label %bb43
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bb43:
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%a = phi i32 [ undef, %loop1 ], [ 0, %bb45 ], [ %a, %bb54 ]
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%b = phi i32 [ 0, %loop1 ], [ 1, %bb54 ], [ %c, %bb45 ]
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br i1 true, label %bb114, label %header
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bb114:
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%c = add i32 0, 1
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%d = add i32 0, 1
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br i1 true, label %bb45, label %bb54
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bb45:
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%x = add i32 %d, 0
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br label %bb43
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bb54:
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br label %bb43
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}
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; CHECK-LABEL: @foo2
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define void @foo2() {
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entry:
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br label %outer
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outer.loopexit:
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br label %outer
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outer:
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br label %loop1
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loop1:
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br i1 true, label %loop1, label %loop2.preheader
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loop2.preheader:
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%a.ph = phi i32 [ undef, %loop1 ]
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%b.ph = phi i32 [ 0, %loop1 ]
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br label %loop2
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loop2:
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%a = phi i32 [ 0, %loop2.if.true ], [ %a, %loop2.if.false ], [ %a.ph, %loop2.preheader ], [0, %bb]
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%b = phi i32 [ 1, %loop2.if.false ], [ %c, %loop2.if.true ], [ %b.ph, %loop2.preheader ], [%c, %bb]
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br i1 true, label %loop2.if, label %outer.loopexit
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loop2.if:
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%c = add i32 0, 1
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switch i32 undef, label %loop2.if.false [i32 0, label %loop2.if.true
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i32 1, label %bb]
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loop2.if.true:
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br i1 undef, label %loop2, label %bb
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loop2.if.false:
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br label %loop2
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bb:
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br label %loop2
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}
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