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Fix a case where UnswitchTrivialCondition broke critical edges with
phi's in the successors git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26108 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -34,6 +34,7 @@
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/CommandLine.h"
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@ -255,6 +256,8 @@ bool LoopUnswitch::visitLoop(Loop *L) {
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// loop.
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for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
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I != E; ++I) {
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for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
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BBI != E; ++BBI)
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TerminatorInst *TI = (*I)->getTerminator();
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// FIXME: Handle invariant select instructions.
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@ -415,7 +418,27 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
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// Split this block now, so that the loop maintains its exit block.
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assert(!L->contains(ExitBlock) && "Exit block is in the loop?");
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BasicBlock *NewExit = SplitBlock(ExitBlock, true);
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BasicBlock *NewExit;
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if (BasicBlock *SinglePred = ExitBlock->getSinglePredecessor()) {
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assert(SinglePred == L->getLoopLatch() && "Unexpected case");
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NewExit = SplitBlock(ExitBlock, true);
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} else {
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// Otherwise, this is a critical edge. Split block would split the wrong
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// edge here, so we use SplitCriticalEdge, which allows us to specify the
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// edge to split, not just the block.
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TerminatorInst *LatchTerm = L->getLoopLatch()->getTerminator();
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unsigned SuccNum = 0;
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for (unsigned i = 0, e = LatchTerm->getNumSuccessors(); ; ++i) {
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assert(i != e && "Didn't find edge?");
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if (LatchTerm->getSuccessor(i) == ExitBlock) {
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SuccNum = i;
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break;
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}
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}
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SplitCriticalEdge(LatchTerm, SuccNum, this);
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NewExit = LatchTerm->getSuccessor(SuccNum);
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assert(NewExit != ExitBlock && "Edge not split!");
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}
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// Okay, now we have a position to branch from and a position to branch to,
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// insert the new conditional branch.
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