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Simplify code a bit, and fix bug CodeExtractor/2004-03-14-NoSwitchSupport.ll
This also implements a two minor improvements: * Don't insert live-out stores IN the region, insert them on the code path that exits the region * If the region is exited to the same block from multiple paths, share the switch statement entry, live-out store code, and the basic block. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12401 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -336,11 +336,10 @@ Function *CodeExtractor::constructFunction(const Values &inputs,
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return newFunction;
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}
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void CodeExtractor::moveCodeToFunction(Function *newFunction)
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{
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void CodeExtractor::moveCodeToFunction(Function *newFunction) {
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Function *oldFunc = (*BlocksToExtract.begin())->getParent();
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Function::BasicBlockListType &oldBlocks = oldFunc->getBasicBlockList();
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Function::BasicBlockListType &newBlocks = newFunction->getBasicBlockList();
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Function::BasicBlockListType &newBlocks = newFunction->getBasicBlockList();
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for (std::set<BasicBlock*>::const_iterator i = BlocksToExtract.begin(),
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e = BlocksToExtract.end(); i != e; ++i) {
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@ -390,6 +389,7 @@ CodeExtractor::emitCallAndSwitchStatement(Function *newFunction,
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params.push_back(*i);
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}
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}
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CallInst *call = new CallInst(newFunction, params, "targetBlock");
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codeReplacer->getInstList().push_back(call);
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codeReplacer->getInstList().push_back(new BranchInst(codeReplacerTail));
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@ -405,70 +405,42 @@ CodeExtractor::emitCallAndSwitchStatement(Function *newFunction,
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codeReplacerTail);
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// Since there may be multiple exits from the original region, make the new
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// function return an unsigned, switch on that number
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// function return an unsigned, switch on that number. This loop iterates
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// over all of the blocks in the extracted region, updating any terminator
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// instructions in the to-be-extracted region that branch to blocks that are
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// not in the region to be extracted.
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std::map<BasicBlock*, BasicBlock*> ExitBlockMap;
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unsigned switchVal = 0;
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for (std::set<BasicBlock*>::const_iterator i = BlocksToExtract.begin(),
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e = BlocksToExtract.end(); i != e; ++i) {
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BasicBlock *BB = *i;
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TerminatorInst *TI = (*i)->getTerminator();
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for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
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if (!BlocksToExtract.count(TI->getSuccessor(i))) {
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BasicBlock *OldTarget = TI->getSuccessor(i);
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// add a new basic block which returns the appropriate value
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BasicBlock *&NewTarget = ExitBlockMap[OldTarget];
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if (!NewTarget) {
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// If we don't already have an exit stub for this non-extracted
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// destination, create one now!
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NewTarget = new BasicBlock(OldTarget->getName() + ".exitStub",
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newFunction);
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// rewrite the terminator of the original BasicBlock
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Instruction *term = BB->getTerminator();
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if (BranchInst *brInst = dyn_cast<BranchInst>(term)) {
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ConstantUInt *brVal = ConstantUInt::get(Type::UShortTy, switchVal++);
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ReturnInst *NTRet = new ReturnInst(brVal, NewTarget);
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// Restore values just before we exit
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// FIXME: Use a GetElementPtr to bunch the outputs in a struct
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for (unsigned outIdx = 0, outE = outputs.size(); outIdx != outE; ++outIdx)
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new StoreInst(outputs[outIdx],
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getFunctionArg(newFunction, outIdx),
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brInst);
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// Update the switch instruction.
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switchInst->addCase(brVal, OldTarget);
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// Rewrite branches into exits which return a value based on which
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// exit we take from this function
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if (brInst->isUnconditional()) {
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if (!BlocksToExtract.count(brInst->getSuccessor(0))) {
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ConstantUInt *brVal = ConstantUInt::get(Type::UShortTy, switchVal);
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ReturnInst *newRet = new ReturnInst(brVal);
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// add a new target to the switch
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switchInst->addCase(brVal, brInst->getSuccessor(0));
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++switchVal;
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// rewrite the branch with a return
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BasicBlock::iterator ii(brInst);
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ReplaceInstWithInst(BB->getInstList(), ii, newRet);
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delete brInst;
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}
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} else {
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// Replace the conditional branch to branch
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// to two new blocks, each of which returns a different code.
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for (unsigned idx = 0; idx < 2; ++idx) {
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BasicBlock *oldTarget = brInst->getSuccessor(idx);
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if (!BlocksToExtract.count(oldTarget)) {
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// add a new basic block which returns the appropriate value
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BasicBlock *newTarget = new BasicBlock("newTarget", newFunction);
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ConstantUInt *brVal = ConstantUInt::get(Type::UShortTy, switchVal);
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ReturnInst *newRet = new ReturnInst(brVal);
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newTarget->getInstList().push_back(newRet);
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// rewrite the original branch instruction with this new target
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brInst->setSuccessor(idx, newTarget);
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// the switch statement knows what to do with this value
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switchInst->addCase(brVal, oldTarget);
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++switchVal;
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}
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// Restore values just before we exit
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// FIXME: Use a GetElementPtr to bunch the outputs in a struct
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for (unsigned out = 0, e = outputs.size(); out != e; ++out)
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new StoreInst(outputs[out], getFunctionArg(newFunction, out),NTRet);
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}
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// rewrite the original branch instruction with this new target
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TI->setSuccessor(i, NewTarget);
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}
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} else if (SwitchInst *swTerm = dyn_cast<SwitchInst>(term)) {
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assert(0 && "Cannot handle switch instructions just yet.");
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} else if (ReturnInst *retTerm = dyn_cast<ReturnInst>(term)) {
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assert(0 && "Cannot handle return instructions just yet.");
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// FIXME: what if the terminator is a return!??!
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// Need to rewrite: add new basic block, move the return there
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// treat the original as an unconditional branch to that basicblock
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} else if (InvokeInst *invInst = dyn_cast<InvokeInst>(term)) {
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assert(0 && "Cannot handle invoke instructions just yet.");
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} else {
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assert(0 && "Unrecognized terminator, or badly-formed BasicBlock.");
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}
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}
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}
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