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Preserve dominance frontier while trivially unswitching loop.

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llvm-svn: 52438
This commit is contained in:
Devang Patel 2008-06-18 02:16:38 +00:00
parent 960d6ae6d1
commit 8f157a3670
2 changed files with 39 additions and 0 deletions
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17
lib/Transforms/Scalar/LoopUnswitch.cpp
View File

@ -610,6 +610,23 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
DT->changeImmediateDominator(NewExit, OrigPH);
DT->changeImmediateDominator(NewPH, OrigPH);
}
if (DF) {
// NewExit is now part of NewPH and Loop Header's dominance
// frontier.
DominanceFrontier::iterator DFI = DF->find(NewPH);
if (DFI != DF->end())
DF->addToFrontier(DFI, NewExit);
DFI = DF->find(L->getHeader());
DF->addToFrontier(DFI, NewExit);
// ExitBlock does not have successors then NewExit is part of
// its dominance frontier.
if (succ_begin(ExitBlock) == succ_end(ExitBlock)) {
DFI = DF->find(ExitBlock);
DF->addToFrontier(DFI, NewExit);
}
}
LPM->deleteSimpleAnalysisValue(OrigPH->getTerminator(), L);
OrigPH->getTerminator()->eraseFromParent();

22
test/Transforms/LoopUnswitch/2008-06-17-DomFrontier.ll Normal file
View File

@ -0,0 +1,22 @@
; RUN: llvm-as < %s | opt -licm -loop-unswitch -disable-output
@g_56 = external global i16 ; <i16*> [#uses=2]
define i32 @func_67(i32 %p_68, i8 signext %p_69, i8 signext %p_71) nounwind {
entry:
br label %bb
bb: ; preds = %bb44, %entry
br label %bb3
bb3: ; preds = %bb36, %bb
%bothcond = or i1 false, false ; <i1> [#uses=1]
br i1 %bothcond, label %bb29, label %bb19
bb19: ; preds = %bb3
br i1 false, label %bb36, label %bb29
bb29: ; preds = %bb19, %bb3
ret i32 0
bb36: ; preds = %bb19
store i16 0, i16* @g_56, align 2
br i1 false, label %bb44, label %bb3
bb44: ; preds = %bb44, %bb36
%tmp46 = load i16* @g_56, align 2 ; <i16> [#uses=0]
br i1 false, label %bb, label %bb44
}