forked from OSchip/llvm-project
some code cleanups, use SwitchInst::findCaseValue, reduce indentation
llvm-svn: 100468
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ba930449a9
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c832c1bf69
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@ -231,8 +231,7 @@ bool LoopUnswitch::processCurrentLoop() {
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// block that is branching on a loop-invariant condition, we can unswitch this
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// loop.
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for (Loop::block_iterator I = currentLoop->block_begin(),
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E = currentLoop->block_end();
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I != E; ++I) {
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E = currentLoop->block_end(); I != E; ++I) {
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TerminatorInst *TI = (*I)->getTerminator();
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if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
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// If this isn't branching on an invariant condition, we can't unswitch
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@ -474,7 +473,6 @@ static inline void RemapInstruction(Instruction *I,
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static Loop *CloneLoop(Loop *L, Loop *PL, DenseMap<const Value*, Value*> &VM,
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LoopInfo *LI, LPPassManager *LPM) {
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Loop *New = new Loop();
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LPM->insertLoop(New, PL);
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// Add all of the blocks in L to the new loop.
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@ -565,8 +563,7 @@ void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond,
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/// SplitExitEdges - Split all of the edges from inside the loop to their exit
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/// blocks. Update the appropriate Phi nodes as we do so.
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void LoopUnswitch::SplitExitEdges(Loop *L,
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const SmallVector<BasicBlock *, 8> &ExitBlocks)
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{
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const SmallVector<BasicBlock *, 8> &ExitBlocks){
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for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
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BasicBlock *ExitBlock = ExitBlocks[i];
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@ -884,65 +881,66 @@ void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC,
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U->replaceUsesOfWith(LIC, Replacement);
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Worklist.push_back(U);
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}
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} else {
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// Otherwise, we don't know the precise value of LIC, but we do know that it
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// is certainly NOT "Val". As such, simplify any uses in the loop that we
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// can. This case occurs when we unswitch switch statements.
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for (unsigned i = 0, e = Users.size(); i != e; ++i)
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if (Instruction *U = cast<Instruction>(Users[i])) {
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if (!L->contains(U))
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continue;
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SimplifyCode(Worklist, L);
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return;
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}
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// Otherwise, we don't know the precise value of LIC, but we do know that it
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// is certainly NOT "Val". As such, simplify any uses in the loop that we
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// can. This case occurs when we unswitch switch statements.
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for (unsigned i = 0, e = Users.size(); i != e; ++i) {
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Instruction *U = cast<Instruction>(Users[i]);
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if (!L->contains(U))
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continue;
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Worklist.push_back(U);
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Worklist.push_back(U);
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// If we know that LIC is not Val, use this info to simplify code.
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if (SwitchInst *SI = dyn_cast<SwitchInst>(U)) {
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for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) {
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if (SI->getCaseValue(i) == Val) {
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// Found a dead case value. Don't remove PHI nodes in the
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// successor if they become single-entry, those PHI nodes may
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// be in the Users list.
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// FIXME: This is a hack. We need to keep the successor around
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// and hooked up so as to preserve the loop structure, because
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// trying to update it is complicated. So instead we preserve the
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// loop structure and put the block on a dead code path.
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BasicBlock *Switch = SI->getParent();
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SplitEdge(Switch, SI->getSuccessor(i), this);
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// Compute the successors instead of relying on the return value
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// of SplitEdge, since it may have split the switch successor
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// after PHI nodes.
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BasicBlock *NewSISucc = SI->getSuccessor(i);
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BasicBlock *OldSISucc = *succ_begin(NewSISucc);
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// Create an "unreachable" destination.
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BasicBlock *Abort = BasicBlock::Create(Context, "us-unreachable",
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Switch->getParent(),
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OldSISucc);
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new UnreachableInst(Context, Abort);
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// Force the new case destination to branch to the "unreachable"
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// block while maintaining a (dead) CFG edge to the old block.
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NewSISucc->getTerminator()->eraseFromParent();
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BranchInst::Create(Abort, OldSISucc,
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ConstantInt::getTrue(Context), NewSISucc);
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// Release the PHI operands for this edge.
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for (BasicBlock::iterator II = NewSISucc->begin();
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PHINode *PN = dyn_cast<PHINode>(II); ++II)
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PN->setIncomingValue(PN->getBasicBlockIndex(Switch),
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UndefValue::get(PN->getType()));
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// Tell the domtree about the new block. We don't fully update the
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// domtree here -- instead we force it to do a full recomputation
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// after the pass is complete -- but we do need to inform it of
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// new blocks.
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if (DT)
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DT->addNewBlock(Abort, NewSISucc);
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break;
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}
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}
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}
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// TODO: We could do other simplifications, for example, turning
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// 'icmp eq LIC, Val' -> false.
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// If we know that LIC is not Val, use this info to simplify code.
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SwitchInst *SI = dyn_cast<SwitchInst>(U);
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if (SI == 0 || !isa<ConstantInt>(Val)) continue;
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unsigned DeadCase = SI->findCaseValue(cast<ConstantInt>(Val));
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if (DeadCase == 0) continue; // Default case is live for multiple values.
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// Found a dead case value. Don't remove PHI nodes in the
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// successor if they become single-entry, those PHI nodes may
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// be in the Users list.
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// TODO: We could do other simplifications, for example, turning
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// LIC == Val -> false.
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}
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// FIXME: This is a hack. We need to keep the successor around
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// and hooked up so as to preserve the loop structure, because
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// trying to update it is complicated. So instead we preserve the
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// loop structure and put the block on a dead code path.
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BasicBlock *Switch = SI->getParent();
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SplitEdge(Switch, SI->getSuccessor(DeadCase), this);
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// Compute the successors instead of relying on the return value
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// of SplitEdge, since it may have split the switch successor
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// after PHI nodes.
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BasicBlock *NewSISucc = SI->getSuccessor(DeadCase);
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BasicBlock *OldSISucc = *succ_begin(NewSISucc);
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// Create an "unreachable" destination.
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BasicBlock *Abort = BasicBlock::Create(Context, "us-unreachable",
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Switch->getParent(),
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OldSISucc);
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new UnreachableInst(Context, Abort);
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// Force the new case destination to branch to the "unreachable"
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// block while maintaining a (dead) CFG edge to the old block.
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NewSISucc->getTerminator()->eraseFromParent();
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BranchInst::Create(Abort, OldSISucc,
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ConstantInt::getTrue(Context), NewSISucc);
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// Release the PHI operands for this edge.
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for (BasicBlock::iterator II = NewSISucc->begin();
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PHINode *PN = dyn_cast<PHINode>(II); ++II)
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PN->setIncomingValue(PN->getBasicBlockIndex(Switch),
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UndefValue::get(PN->getType()));
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// Tell the domtree about the new block. We don't fully update the
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// domtree here -- instead we force it to do a full recomputation
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// after the pass is complete -- but we do need to inform it of
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// new blocks.
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if (DT)
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DT->addNewBlock(Abort, NewSISucc);
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}
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SimplifyCode(Worklist, L);
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@ -1054,7 +1052,10 @@ void LoopUnswitch::SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L) {
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LPM->deleteSimpleAnalysisValue(Succ, L);
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Succ->eraseFromParent();
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++NumSimplify;
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} else if (ConstantInt *CB = dyn_cast<ConstantInt>(BI->getCondition())){
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break;
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}
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if (ConstantInt *CB = dyn_cast<ConstantInt>(BI->getCondition())){
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// Conditional branch. Turn it into an unconditional branch, then
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// remove dead blocks.
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break; // FIXME: Enable.
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