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Seriously simplify and correct the PHI node handling code.

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llvm-svn: 12487
This commit is contained in:
Chris Lattner 2004-03-18 05:28:49 +00:00
parent 345cf6f177
commit 69fdd9f14a
1 changed files with 28 additions and 162 deletions
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190
lib/Transforms/Utils/CodeExtractor.cpp
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@ -30,20 +30,8 @@
using namespace llvm;
namespace {
/// getFunctionArg - Return a pointer to F's ARGNOth argument.
///
Argument *getFunctionArg(Function *F, unsigned argno) {
Function::aiterator I = F->abegin();
std::advance(I, argno);
return I;
}
class CodeExtractor {
typedef std::vector<Value*> Values;
typedef std::vector<std::pair<unsigned, unsigned> > PhiValChangesTy;
typedef std::map<PHINode*, PhiValChangesTy> PhiVal2ArgTy;
PhiVal2ArgTy PhiVal2Arg;
std::set<BasicBlock*> BlocksToExtract;
DominatorSet *DS;
public:
@ -56,15 +44,9 @@ namespace {
BasicBlock *newHeader,
BasicBlock *newRootNode);
void processPhiNodeInputs(PHINode *Phi,
Values &inputs,
BasicBlock *newHeader,
BasicBlock *newRootNode);
void rewritePhiNodes(Function *F, BasicBlock *newFuncRoot);
Function *constructFunction(const Values &inputs,
const Values &outputs,
BasicBlock *header,
BasicBlock *newRootNode, BasicBlock *newHeader,
Function *oldFunction, Module *M);
@ -78,95 +60,6 @@ namespace {
};
}
void CodeExtractor::processPhiNodeInputs(PHINode *Phi,
Values &inputs,
BasicBlock *codeReplacer,
BasicBlock *newFuncRoot) {
// Separate incoming values and BasicBlocks as internal/external. We ignore
// the case where both the value and BasicBlock are internal, because we don't
// need to do a thing.
std::vector<unsigned> EValEBB;
std::vector<unsigned> EValIBB;
std::vector<unsigned> IValEBB;
for (unsigned i = 0, e = Phi->getNumIncomingValues(); i != e; ++i) {
Value *phiVal = Phi->getIncomingValue(i);
if (Instruction *Inst = dyn_cast<Instruction>(phiVal)) {
if (BlocksToExtract.count(Inst->getParent())) {
if (!BlocksToExtract.count(Phi->getIncomingBlock(i)))
IValEBB.push_back(i);
} else {
if (BlocksToExtract.count(Phi->getIncomingBlock(i)))
EValIBB.push_back(i);
else
EValEBB.push_back(i);
}
} else if (Argument *Arg = dyn_cast<Argument>(phiVal)) {
// arguments are external
if (BlocksToExtract.count(Phi->getIncomingBlock(i)))
EValIBB.push_back(i);
else
EValEBB.push_back(i);
} else {
// Globals/Constants are internal, but considered `external' if they are
// coming from an external block.
if (!BlocksToExtract.count(Phi->getIncomingBlock(i)))
EValEBB.push_back(i);
}
}
// Both value and block are external. Need to group all of these, have an
// external phi, pass the result as an argument, and have THIS phi use that
// result.
if (EValEBB.size() > 0) {
if (EValEBB.size() == 1) {
// Now if it's coming from the newFuncRoot, it's that funky input
unsigned phiIdx = EValEBB[0];
if (!isa<Constant>(Phi->getIncomingValue(phiIdx))) {
PhiVal2Arg[Phi].push_back(std::make_pair(phiIdx, inputs.size()));
// We can just pass this value in as argument
inputs.push_back(Phi->getIncomingValue(phiIdx));
}
Phi->setIncomingBlock(phiIdx, newFuncRoot);
} else {
PHINode *externalPhi = new PHINode(Phi->getType(), "extPhi");
codeReplacer->getInstList().insert(codeReplacer->begin(), externalPhi);
for (std::vector<unsigned>::iterator i = EValEBB.begin(),
e = EValEBB.end(); i != e; ++i) {
externalPhi->addIncoming(Phi->getIncomingValue(*i),
Phi->getIncomingBlock(*i));
// We make these values invalid instead of deleting them because that
// would shift the indices of other values... The fixPhiNodes should
// clean these phi nodes up later.
Phi->setIncomingValue(*i, 0);
Phi->setIncomingBlock(*i, 0);
}
PhiVal2Arg[Phi].push_back(std::make_pair(Phi->getNumIncomingValues(),
inputs.size()));
// We can just pass this value in as argument
inputs.push_back(externalPhi);
}
}
// When the value is external, but block internal... just pass it in as
// argument, no change to phi node
for (std::vector<unsigned>::iterator i = EValIBB.begin(),
e = EValIBB.end(); i != e; ++i) {
// rewrite the phi input node to be an argument
PhiVal2Arg[Phi].push_back(std::make_pair(*i, inputs.size()));
inputs.push_back(Phi->getIncomingValue(*i));
}
// Value internal, block external this can happen if we are extracting a part
// of a loop.
for (std::vector<unsigned>::iterator i = IValEBB.begin(),
e = IValEBB.end(); i != e; ++i) {
assert(0 && "Cannot (YET) handle internal values via external blocks");
}
}
void CodeExtractor::findInputsOutputs(Values &inputs, Values &outputs,
BasicBlock *newHeader,
BasicBlock *newRootNode) {
@ -176,8 +69,13 @@ void CodeExtractor::findInputsOutputs(Values &inputs, Values &outputs,
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
// If a used value is defined outside the region, it's an input. If an
// instruction is used outside the region, it's an output.
if (PHINode *Phi = dyn_cast<PHINode>(I)) {
processPhiNodeInputs(Phi, inputs, newHeader, newRootNode);
if (PHINode *PN = dyn_cast<PHINode>(I)) {
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
Value *V = PN->getIncomingValue(i);
if (!BlocksToExtract.count(PN->getIncomingBlock(i)) &&
(isa<Instruction>(V) || isa<Argument>(V)))
inputs.push_back(V);
}
} else {
// All other instructions go through the generic input finder
// Loop over the operands of each instruction (inputs)
@ -203,53 +101,18 @@ void CodeExtractor::findInputsOutputs(Values &inputs, Values &outputs,
} // for: basic blocks
}
void CodeExtractor::rewritePhiNodes(Function *F,
BasicBlock *newFuncRoot) {
// Write any changes that were saved before: use function arguments as inputs
for (PhiVal2ArgTy::iterator i = PhiVal2Arg.begin(), e = PhiVal2Arg.end();
i != e; ++i) {
PHINode *phi = i->first;
PhiValChangesTy &values = i->second;
for (unsigned cIdx = 0, ce = values.size(); cIdx != ce; ++cIdx)
{
unsigned phiValueIdx = values[cIdx].first, argNum = values[cIdx].second;
if (phiValueIdx < phi->getNumIncomingValues())
phi->setIncomingValue(phiValueIdx, getFunctionArg(F, argNum));
else
phi->addIncoming(getFunctionArg(F, argNum), newFuncRoot);
}
}
// Delete any invalid Phi node inputs that were marked as NULL previously
for (PhiVal2ArgTy::iterator i = PhiVal2Arg.begin(), e = PhiVal2Arg.end();
i != e; ++i) {
PHINode *phi = i->first;
for (unsigned idx = 0, end = phi->getNumIncomingValues(); idx != end; ++idx)
{
if (phi->getIncomingValue(idx) == 0 && phi->getIncomingBlock(idx) == 0) {
phi->removeIncomingValue(idx);
--idx;
--end;
}
}
}
// We are done with the saved values
PhiVal2Arg.clear();
}
/// constructFunction - make a function based on inputs and outputs, as follows:
/// f(in0, ..., inN, out0, ..., outN)
///
Function *CodeExtractor::constructFunction(const Values &inputs,
const Values &outputs,
BasicBlock *header,
BasicBlock *newRootNode,
BasicBlock *newHeader,
Function *oldFunction, Module *M) {
Function *oldFunction,
Module *M) {
DEBUG(std::cerr << "inputs: " << inputs.size() << "\n");
DEBUG(std::cerr << "outputs: " << outputs.size() << "\n");
BasicBlock *header = *BlocksToExtract.begin();
// This function returns unsigned, outputs will go back by reference.
Type *retTy = Type::UShortTy;
@ -308,17 +171,13 @@ Function *CodeExtractor::constructFunction(const Values &inputs,
// within the new function. This must be done before we lose track of which
// blocks were originally in the code region.
std::vector<User*> Users(header->use_begin(), header->use_end());
for (std::vector<User*>::iterator i = Users.begin(), e = Users.end();
i != e; ++i) {
if (BranchInst *inst = dyn_cast<BranchInst>(*i)) {
BasicBlock *BB = inst->getParent();
if (!BlocksToExtract.count(BB) && BB->getParent() == oldFunction) {
// The BasicBlock which contains the branch is not in the region
// modify the branch target to a new block
inst->replaceUsesOfWith(header, newHeader);
}
}
}
for (unsigned i = 0, e = Users.size(); i != e; ++i)
// The BasicBlock which contains the branch is not in the region
// modify the branch target to a new block
if (TerminatorInst *TI = dyn_cast<TerminatorInst>(Users[i]))
if (!BlocksToExtract.count(TI->getParent()) &&
TI->getParent()->getParent() == oldFunction)
TI->replaceUsesOfWith(header, newHeader);
return newFunction;
}
@ -495,16 +354,23 @@ Function *CodeExtractor::ExtractCodeRegion(const std::vector<BasicBlock*> &code)
// Step 2: Construct new function based on inputs/outputs,
// Add allocas for all defs
Function *newFunction = constructFunction(inputs, outputs, newFuncRoot,
Function *newFunction = constructFunction(inputs, outputs, code[0],
newFuncRoot,
codeReplacer, oldFunction,
oldFunction->getParent());
rewritePhiNodes(newFunction, newFuncRoot);
emitCallAndSwitchStatement(newFunction, codeReplacer, inputs, outputs);
moveCodeToFunction(newFunction);
// Loop over all of the PHI nodes in the entry block (code[0]), and change any
// references to the old incoming edge to be the new incoming edge.
for (BasicBlock::iterator I = code[0]->begin();
PHINode *PN = dyn_cast<PHINode>(I); ++I)
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (!BlocksToExtract.count(PN->getIncomingBlock(i)))
PN->setIncomingBlock(i, newFuncRoot);
DEBUG(if (verifyFunction(*newFunction)) abort());
return newFunction;
}