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Prior load folding check on chain operand was too strict. It requires the 

chain operand to point to the load being folded. Now we relax this, traversing
up the chain, if it doesn't reach the load, then it's ok. We will create a
TokenFactor (of all the chain operands and the load's chain) to capture all
the control flow dependencies.

llvm-svn: 30897
This commit is contained in:
Evan Cheng 2006-10-12 02:08:53 +00:00
parent 77e030bca9
commit d7125583f7
1 changed files with 43 additions and 3 deletions
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46
llvm/utils/TableGen/DAGISelEmitter.cpp
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@ -2138,6 +2138,8 @@ private:
std::map<std::string, Record*> OperatorMap;
// Names of all the folded nodes which produce chains.
std::vector<std::pair<std::string, unsigned> > FoldedChains;
// Original input chain(s).
std::vector<std::pair<std::string, std::string> > OrigChains;
std::set<std::string> Duplicates;
/// GeneratedCode - This is the buffer that we emit code to. The first int
@ -2294,9 +2296,12 @@ public:
}
if (NodeHasChain) {
if (FoundChain)
emitCheck("Chain.Val == " + RootName + ".Val");
else
if (FoundChain) {
emitCheck("(" + ChainName + ".Val == " + RootName + ".Val || "
"IsChainCompatible(" + ChainName + ".Val, " +
RootName + ".Val))");
OrigChains.push_back(std::make_pair(ChainName, RootName));
} else
FoundChain = true;
ChainName = "Chain" + ChainSuffix;
emitInit("SDOperand " + ChainName + " = " + RootName +
@ -2665,6 +2670,26 @@ public:
PatResults++;
}
if (OrigChains.size() > 0) {
// The original input chain is being ignored. If it is not just
// pointing to the op that's being folded, we should create a
// TokenFactor with it and the chain of the folded op as the new chain.
// We could potentially be doing multiple levels of folding, in that
// case, the TokenFactor can have more operands.
emitCode("SmallVector<SDOperand, 8> InChains;");
for (unsigned i = 0, e = OrigChains.size(); i < e; ++i) {
emitCode("if (" + OrigChains[i].first + ".Val != " +
OrigChains[i].second + ".Val) {");
emitCode(" AddToISelQueue(" + OrigChains[i].first + ");");
emitCode(" InChains.push_back(" + OrigChains[i].first + ");");
emitCode("}");
}
emitCode("AddToISelQueue(" + ChainName + ");");
emitCode("InChains.push_back(" + ChainName + ");");
emitCode(ChainName + " = CurDAG->getNode(ISD::TokenFactor, MVT::Other, "
"&InChains[0], InChains.size());");
}
std::vector<std::string> AllOps;
for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i) {
std::vector<std::string> Ops = EmitResultCode(N->getChild(i),
@ -3647,6 +3672,21 @@ void DAGISelEmitter::run(std::ostream &OS) {
OS << "/// Dummy parameter to ReplaceAllUsesOfValueWith().\n"
<< "std::vector<SDNode*> ISelKilled;\n\n";
OS << "/// IsChainCompatible - Returns true if Chain is Op or Chain does\n";
OS << "/// not reach Op.\n";
OS << "static bool IsChainCompatible(SDNode *Chain, SDNode *Op) {\n";
OS << " if (Chain->getOpcode() == ISD::EntryToken)\n";
OS << " return true;\n";
OS << " else if (Chain->getOpcode() == ISD::TokenFactor)\n";
OS << " return false;\n";
OS << " else if (Chain->getNumOperands() > 0) {\n";
OS << " SDOperand C0 = Chain->getOperand(0);\n";
OS << " if (C0.getValueType() == MVT::Other)\n";
OS << " return C0.Val != Op && IsChainCompatible(C0.Val, Op);\n";
OS << " }\n";
OS << " return true;\n";
OS << "}\n";
OS << "/// Sorting functions for the selection queue.\n"
<< "struct isel_sort : public std::binary_function"
<< "<SDNode*, SDNode*, bool> {\n"