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[LoopSimplifyCFG] Fix order of deletion of complex dead subloops

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Function `DeleteDeadBlock` requires that all predecessors of a block
being deleted have already been deleted, with the exception of a
single-block loop. When we use it for removal of dead subloops that
contain more than one block, we may not fulfull this requirement and
fail an assertion.

This patch replaces invocation of `DeleteDeadBlock` with a generalized
version `DeleteDeadBlocks` that is able to deal with multiple dead blocks,
even if they contain some cycles.

Differential Revision: https://reviews.llvm.org/D56121
Reviewed By: fedor.sergeev

llvm-svn: 351433
This commit is contained in:
Max Kazantsev 2019-01-17 12:25:40 +00:00
parent f7ba65d569
commit 09052af6c2
2 changed files with 21 additions and 5 deletions
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5
lib/Transforms/Scalar/LoopSimplifyCFG.cpp
View File

@ -402,9 +402,10 @@ private:
LI.erase(LI.getLoopFor(BB));
}
LI.removeBlock(BB);
DeleteDeadBlock(BB, &DTU);
++NumLoopBlocksDeleted;
}
DeleteDeadBlocks(DeadLoopBlocks, &DTU);
NumLoopBlocksDeleted += DeadLoopBlocks.size();
}
/// Constant-fold terminators of blocks acculumated in FoldCandidates into the

21
test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll
View File

@ -1,7 +1,4 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; XFAIL: *
; Tests complex_dead_subloop_branch and complex_dead_subloop_switch fail an
; assertion, therefore the CFG simplification is temporarily disabled.
; REQUIRES: asserts
; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -loop-simplifycfg -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -passes='require<domtree>,loop(simplify-cfg)' -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
@ -2512,6 +2509,15 @@ exit:
}
define i32 @complex_dead_subloop_branch(i1 %cond1, i1 %cond2, i1 %cond3) {
; CHECK-LABEL: @complex_dead_subloop_branch(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: br i1 [[COND3:%.*]], label [[LOOP]], label [[EXIT:%.*]]
; CHECK: exit:
; CHECK-NEXT: [[RESULT_LCSSA:%.*]] = phi i32 [ 0, [[LOOP]] ]
; CHECK-NEXT: ret i32 [[RESULT_LCSSA]]
;
entry:
br label %loop
@ -2540,6 +2546,15 @@ exit:
}
define i32 @complex_dead_subloop_switch(i1 %cond1, i1 %cond2, i1 %cond3) {
; CHECK-LABEL: @complex_dead_subloop_switch(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: br i1 [[COND3:%.*]], label [[LOOP]], label [[EXIT:%.*]]
; CHECK: exit:
; CHECK-NEXT: [[RESULT_LCSSA:%.*]] = phi i32 [ 0, [[LOOP]] ]
; CHECK-NEXT: ret i32 [[RESULT_LCSSA]]
;
entry:
br label %loop