Revert "Revert r275883 and r275891. They seem to cause PR28608."
This reverts commit r276064, and thus reapplies r275891 and r275883 with
a fix for PR28608.
llvm-svn: 276077
diff --git a/llvm/lib/Transforms/Utils/LoopSimplify.cpp b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
index b3a928b..2846e8f 100644
--- a/llvm/lib/Transforms/Utils/LoopSimplify.cpp
+++ b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
@@ -327,6 +327,8 @@
else
NewOuter->addChildLoop(L->removeChildLoop(SubLoops.begin() + I));
+ SmallVector<BasicBlock *, 8> OuterLoopBlocks;
+ OuterLoopBlocks.push_back(NewBB);
// Now that we know which blocks are in L and which need to be moved to
// OuterLoop, move any blocks that need it.
for (unsigned i = 0; i != L->getBlocks().size(); ++i) {
@@ -334,12 +336,53 @@
if (!BlocksInL.count(BB)) {
// Move this block to the parent, updating the exit blocks sets
L->removeBlockFromLoop(BB);
- if ((*LI)[BB] == L)
+ if ((*LI)[BB] == L) {
LI->changeLoopFor(BB, NewOuter);
+ OuterLoopBlocks.push_back(BB);
+ }
--i;
}
}
+ // Split edges to exit blocks from the inner loop, if they emerged in the
+ // process of separating the outer one.
+ SmallVector<BasicBlock *, 8> ExitBlocks;
+ L->getExitBlocks(ExitBlocks);
+ SmallSetVector<BasicBlock *, 8> ExitBlockSet(ExitBlocks.begin(),
+ ExitBlocks.end());
+ for (BasicBlock *ExitBlock : ExitBlockSet) {
+ if (any_of(predecessors(ExitBlock),
+ [L](BasicBlock *BB) { return !L->contains(BB); })) {
+ rewriteLoopExitBlock(L, ExitBlock, DT, LI, PreserveLCSSA);
+ }
+ }
+
+ if (PreserveLCSSA) {
+ // Fix LCSSA form for L. Some values, which previously were only used inside
+ // L, can now be used in NewOuter loop. We need to insert phi-nodes for them
+ // in corresponding exit blocks.
+
+ // Go through all instructions in OuterLoopBlocks and check if they are
+ // using operands from the inner loop. In this case we'll need to fix LCSSA
+ // for these instructions.
+ SmallSetVector<Instruction *, 8> WorklistSet;
+ for (BasicBlock *OuterBB: OuterLoopBlocks) {
+ for (Instruction &I : *OuterBB) {
+ for (Value *Op : I.operands()) {
+ Instruction *OpI = dyn_cast<Instruction>(Op);
+ if (!OpI || !L->contains(OpI))
+ continue;
+ WorklistSet.insert(OpI);
+ }
+ }
+ }
+ SmallVector<Instruction *, 8> Worklist(WorklistSet.begin(),
+ WorklistSet.end());
+ formLCSSAForInstructions(Worklist, *DT, *LI);
+ assert(NewOuter->isRecursivelyLCSSAForm(*DT) &&
+ "LCSSA is broken after separating nested loops!");
+ }
+
return NewOuter;
}
@@ -541,17 +584,12 @@
SmallSetVector<BasicBlock *, 8> ExitBlockSet(ExitBlocks.begin(),
ExitBlocks.end());
for (BasicBlock *ExitBlock : ExitBlockSet) {
- for (pred_iterator PI = pred_begin(ExitBlock), PE = pred_end(ExitBlock);
- PI != PE; ++PI)
- // Must be exactly this loop: no subloops, parent loops, or non-loop preds
- // allowed.
- if (!L->contains(*PI)) {
- if (rewriteLoopExitBlock(L, ExitBlock, DT, LI, PreserveLCSSA)) {
- ++NumInserted;
- Changed = true;
- }
- break;
- }
+ if (any_of(predecessors(ExitBlock),
+ [L](BasicBlock *BB) { return !L->contains(BB); })) {
+ rewriteLoopExitBlock(L, ExitBlock, DT, LI, PreserveLCSSA);
+ ++NumInserted;
+ Changed = true;
+ }
}
// If the header has more than two predecessors at this point (from the