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Simplify code a bit, and fix bug CodeExtractor/2004-03-14-NoSwitchSupport.ll

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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.

llvm-svn: 12401
This commit is contained in:
Chris Lattner 2004-03-14 23:05:49 +00:00
parent f8d6c1a252
commit 17c2c776c3
1 changed files with 31 additions and 59 deletions
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90
lib/Transforms/Utils/CodeExtractor.cpp
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@ -336,11 +336,10 @@ Function *CodeExtractor::constructFunction(const Values &inputs,
return newFunction;
}
void CodeExtractor::moveCodeToFunction(Function *newFunction)
{
void CodeExtractor::moveCodeToFunction(Function *newFunction) {
Function *oldFunc = (*BlocksToExtract.begin())->getParent();
Function::BasicBlockListType &oldBlocks = oldFunc->getBasicBlockList();
Function::BasicBlockListType &newBlocks = newFunction->getBasicBlockList();
Function::BasicBlockListType &newBlocks = newFunction->getBasicBlockList();
for (std::set<BasicBlock*>::const_iterator i = BlocksToExtract.begin(),
e = BlocksToExtract.end(); i != e; ++i) {
@ -390,6 +389,7 @@ CodeExtractor::emitCallAndSwitchStatement(Function *newFunction,
params.push_back(*i);
}
}
CallInst *call = new CallInst(newFunction, params, "targetBlock");
codeReplacer->getInstList().push_back(call);
codeReplacer->getInstList().push_back(new BranchInst(codeReplacerTail));
@ -405,70 +405,42 @@ CodeExtractor::emitCallAndSwitchStatement(Function *newFunction,
codeReplacerTail);
// Since there may be multiple exits from the original region, make the new
// function return an unsigned, switch on that number
// function return an unsigned, switch on that number. This loop iterates
// over all of the blocks in the extracted region, updating any terminator
// instructions in the to-be-extracted region that branch to blocks that are
// not in the region to be extracted.
std::map<BasicBlock*, BasicBlock*> ExitBlockMap;
unsigned switchVal = 0;
for (std::set<BasicBlock*>::const_iterator i = BlocksToExtract.begin(),
e = BlocksToExtract.end(); i != e; ++i) {
BasicBlock *BB = *i;
TerminatorInst *TI = (*i)->getTerminator();
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
if (!BlocksToExtract.count(TI->getSuccessor(i))) {
BasicBlock *OldTarget = TI->getSuccessor(i);
// add a new basic block which returns the appropriate value
BasicBlock *&NewTarget = ExitBlockMap[OldTarget];
if (!NewTarget) {
// If we don't already have an exit stub for this non-extracted
// destination, create one now!
NewTarget = new BasicBlock(OldTarget->getName() + ".exitStub",
newFunction);
// rewrite the terminator of the original BasicBlock
Instruction *term = BB->getTerminator();
if (BranchInst *brInst = dyn_cast<BranchInst>(term)) {
ConstantUInt *brVal = ConstantUInt::get(Type::UShortTy, switchVal++);
ReturnInst *NTRet = new ReturnInst(brVal, NewTarget);
// Restore values just before we exit
// FIXME: Use a GetElementPtr to bunch the outputs in a struct
for (unsigned outIdx = 0, outE = outputs.size(); outIdx != outE; ++outIdx)
new StoreInst(outputs[outIdx],
getFunctionArg(newFunction, outIdx),
brInst);
// Update the switch instruction.
switchInst->addCase(brVal, OldTarget);
// Rewrite branches into exits which return a value based on which
// exit we take from this function
if (brInst->isUnconditional()) {
if (!BlocksToExtract.count(brInst->getSuccessor(0))) {
ConstantUInt *brVal = ConstantUInt::get(Type::UShortTy, switchVal);
ReturnInst *newRet = new ReturnInst(brVal);
// add a new target to the switch
switchInst->addCase(brVal, brInst->getSuccessor(0));
++switchVal;
// rewrite the branch with a return
BasicBlock::iterator ii(brInst);
ReplaceInstWithInst(BB->getInstList(), ii, newRet);
delete brInst;
}
} else {
// Replace the conditional branch to branch
// to two new blocks, each of which returns a different code.
for (unsigned idx = 0; idx < 2; ++idx) {
BasicBlock *oldTarget = brInst->getSuccessor(idx);
if (!BlocksToExtract.count(oldTarget)) {
// add a new basic block which returns the appropriate value
BasicBlock *newTarget = new BasicBlock("newTarget", newFunction);
ConstantUInt *brVal = ConstantUInt::get(Type::UShortTy, switchVal);
ReturnInst *newRet = new ReturnInst(brVal);
newTarget->getInstList().push_back(newRet);
// rewrite the original branch instruction with this new target
brInst->setSuccessor(idx, newTarget);
// the switch statement knows what to do with this value
switchInst->addCase(brVal, oldTarget);
++switchVal;
}
// Restore values just before we exit
// FIXME: Use a GetElementPtr to bunch the outputs in a struct
for (unsigned out = 0, e = outputs.size(); out != e; ++out)
new StoreInst(outputs[out], getFunctionArg(newFunction, out),NTRet);
}
// rewrite the original branch instruction with this new target
TI->setSuccessor(i, NewTarget);
}
} else if (SwitchInst *swTerm = dyn_cast<SwitchInst>(term)) {
assert(0 && "Cannot handle switch instructions just yet.");
} else if (ReturnInst *retTerm = dyn_cast<ReturnInst>(term)) {
assert(0 && "Cannot handle return instructions just yet.");
// FIXME: what if the terminator is a return!??!
// Need to rewrite: add new basic block, move the return there
// treat the original as an unconditional branch to that basicblock
} else if (InvokeInst *invInst = dyn_cast<InvokeInst>(term)) {
assert(0 && "Cannot handle invoke instructions just yet.");
} else {
assert(0 && "Unrecognized terminator, or badly-formed BasicBlock.");
}
}
}