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Fix a corner case in updating LoopInfo after fully unrolling an outer loop. 

The loop tree's inclusive block lists are painful and expensive to
update. (I have no idea why they're inclusive). The design was
supposed to handle this case but the implementation missed it and my
unit tests weren't thorough enough.

Fixes PR11335: loop unroll update.

llvm-svn: 144970
This commit is contained in:
Andrew Trick 2011-11-18 03:42:41 +00:00
parent 00f43622e1
commit 6b4d578f54
2 changed files with 50 additions and 11 deletions
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20
llvm/lib/Analysis/LoopInfo.cpp
View File

@ -477,21 +477,19 @@ void UnloopUpdater::updateBlockParents() {
/// removeBlocksFromAncestors - Remove unloop's blocks from all ancestors below
/// their new parents.
void UnloopUpdater::removeBlocksFromAncestors() {
// Remove unloop's blocks from all ancestors below their new parents.
// Remove all unloop's blocks (including those in nested subloops) from
// ancestors below the new parent loop.
for (Loop::block_iterator BI = Unloop->block_begin(),
BE = Unloop->block_end(); BI != BE; ++BI) {
Loop *NewParent = LI->getLoopFor(*BI);
// If this block is an immediate subloop, remove all blocks (including
// nested subloops) from ancestors below the new parent loop.
// Otherwise, if this block is in a nested subloop, skip it.
if (SubloopParents.count(NewParent))
NewParent = SubloopParents[NewParent];
else if (Unloop->contains(NewParent))
continue;
Loop *OuterParent = LI->getLoopFor(*BI);
if (Unloop->contains(OuterParent)) {
while (OuterParent->getParentLoop() != Unloop)
OuterParent = OuterParent->getParentLoop();
OuterParent = SubloopParents[OuterParent];
}
// Remove blocks from former Ancestors except Unloop itself which will be
// deleted.
for (Loop *OldParent = Unloop->getParentLoop(); OldParent != NewParent;
for (Loop *OldParent = Unloop->getParentLoop(); OldParent != OuterParent;
OldParent = OldParent->getParentLoop()) {
assert(OldParent && "new loop is not an ancestor of the original");
OldParent->removeBlockFromLoop(*BI);

41
llvm/test/Transforms/LoopUnroll/unloop.ll
View File

@ -427,3 +427,44 @@ if.end2413: ; preds = %defchar
return: ; preds = %sw.bb304
ret void
}
; PR11335: the most deeply nested block should be removed from the outer loop.
; CHECK: @removeSubloopBlocks2
; CHECK: for.cond3:
; CHECK-NOT: br
; CHECK: ret void
define void @removeSubloopBlocks2() nounwind {
entry:
%tobool.i = icmp ne i32 undef, 0
br label %lbl_616
lbl_616.loopexit: ; preds = %for.cond
br label %lbl_616
lbl_616: ; preds = %lbl_616.loopexit, %entry
br label %for.cond
for.cond: ; preds = %for.cond3, %lbl_616
br i1 false, label %for.cond1.preheader, label %lbl_616.loopexit
for.cond1.preheader: ; preds = %for.cond
br label %for.cond1
for.cond1.loopexit: ; preds = %for.cond.i
br label %for.cond1
for.cond1: ; preds = %for.cond1.loopexit, %for.cond1.preheader
br i1 false, label %for.body2, label %for.cond3
for.body2: ; preds = %for.cond1
br label %for.cond.i
for.cond.i: ; preds = %for.cond.i, %for.body2
br i1 %tobool.i, label %for.cond.i, label %for.cond1.loopexit
for.cond3: ; preds = %for.cond1
br i1 false, label %for.cond, label %if.end
if.end: ; preds = %for.cond3
ret void
}