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

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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 686cc9cacc
commit 65264c811f
1 changed files with 43 additions and 3 deletions
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46
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"