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The commit rL308422 introduces a restriction for folding unconditional branches. Specifically if empty block with unconditional branch leads to header of the loop then elimination of this basic block is prohibited. However it seems this condition is redundantly strict. If elimination of this basic block does not introduce more back edges then we can eliminate this block. The patch implements this relax of restriction. The test profile/Linux/counter_promo_nest.c in compiler-rt project is updated to meet this change. Reviewers: efriedma, mcrosier, pacxx, hsung, davidxl Reviewed By: pacxx Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D42691 llvm-svn: 324572
59 lines
1.5 KiB
LLVM
59 lines
1.5 KiB
LLVM
; REQUIRES: asserts
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; RUN: opt -loop-unswitch -disable-output -stats -info-output-file - < %s | FileCheck --check-prefix=STATS %s
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; RUN: opt -loop-unswitch -simplifycfg -S < %s | FileCheck %s
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; PR5373
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; Loop unswitching shouldn't trivially unswitch the true case of condition %a
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; in the code here because it leads to an infinite loop. While this doesn't
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; contain any instructions with side effects, it's still a kind of side effect.
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; It can trivially unswitch on the false case of condition %a though.
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; STATS: 2 loop-unswitch - Number of branches unswitched
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; STATS: 2 loop-unswitch - Number of unswitches that are trivial
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; CHECK-LABEL: @func_16(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: br i1 %a, label %entry.split, label %abort0.split
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; CHECK: entry.split:
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; CHECK-NEXT: br i1 %b, label %for.body, label %abort1.split
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; CHECK: for.body:
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; CHECK-NEXT: br label %for.body
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; CHECK: abort0.split:
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; CHECK-NEXT: call void @end0() [[NOR_NUW:#[0-9]+]]
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; CHECK-NEXT: unreachable
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; CHECK: abort1.split:
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; CHECK-NEXT: call void @end1() [[NOR_NUW]]
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; CHECK-NEXT: unreachable
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; CHECK: }
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define void @func_16(i1 %a, i1 %b) nounwind {
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entry:
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br label %for.body
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for.body:
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br i1 %a, label %cond.end, label %abort0
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cond.end:
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br i1 %b, label %for.body, label %abort1
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abort0:
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call void @end0() noreturn nounwind
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unreachable
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abort1:
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call void @end1() noreturn nounwind
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unreachable
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}
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declare void @end0() noreturn
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declare void @end1() noreturn
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; CHECK: attributes #0 = { nounwind }
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; CHECK: attributes #1 = { noreturn }
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; CHECK: attributes [[NOR_NUW]] = { noreturn nounwind }
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