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Make this check stricter. Disallow loop exit blocks from being shared by

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loops and their subloops.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26118 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-02-11 02:13:17 +00:00
parent 2486af1b53
commit 8587eb3a51
1 changed files with 7 additions and 4 deletions
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11
lib/Transforms/Utils/LoopSimplify.cpp
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@ -109,7 +109,6 @@ bool LoopSimplify::runOnFunction(Function &F) {
return Changed;
}
/// ProcessLoop - Walk the loop structure in depth first order, ensuring that
/// all loops have preheaders.
///
@ -162,12 +161,15 @@ bool LoopSimplify::ProcessLoop(Loop *L) {
L->getExitBlocks(ExitBlocks);
SetVector<BasicBlock*> ExitBlockSet(ExitBlocks.begin(), ExitBlocks.end());
LoopInfo &LI = getAnalysis<LoopInfo>();
for (SetVector<BasicBlock*>::iterator I = ExitBlockSet.begin(),
E = ExitBlockSet.end(); I != E; ++I) {
BasicBlock *ExitBlock = *I;
for (pred_iterator PI = pred_begin(ExitBlock), PE = pred_end(ExitBlock);
PI != PE; ++PI)
if (!L->contains(*PI)) {
// Must be exactly this loop: no subloops, parent loops, or non-loop preds
// allowed.
if (LI.getLoopFor(*PI) != L) {
RewriteLoopExitBlock(L, ExitBlock);
NumInserted++;
Changed = true;
@ -178,6 +180,7 @@ bool LoopSimplify::ProcessLoop(Loop *L) {
// If the header has more than two predecessors at this point (from the
// preheader and from multiple backedges), we must adjust the loop.
if (L->getNumBackEdges() != 1) {
// If this is really a nested loop, rip it out into a child loop.
if (Loop *NL = SeparateNestedLoop(L)) {
++NumNested;
@ -310,8 +313,8 @@ void LoopSimplify::InsertPreheaderForLoop(Loop *L) {
std::vector<BasicBlock*> OutsideBlocks;
for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
PI != PE; ++PI)
if (!L->contains(*PI)) // Coming in from outside the loop?
OutsideBlocks.push_back(*PI); // Keep track of it...
if (!L->contains(*PI)) // Coming in from outside the loop?
OutsideBlocks.push_back(*PI); // Keep track of it...
// Split out the loop pre-header
BasicBlock *NewBB =