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[TableGen] Split DAGISelMatcherOpt FactorNodes into 2 functions. NFC #125330

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Merged
topperc merged 2 commits into from
Feb 3, 2025
Merged

[TableGen] Split DAGISelMatcherOpt FactorNodes into 2 functions. NFC #125330

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TableGen] Split DAGISelMatcherOpt FactorNodes into 2 functions. NFC
topperc Feb 1, 2025
909a083
fixup! Cleanup comments a little.
topperc Feb 2, 2025
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61 changes: 31 additions & 30 deletions llvm/utils/TableGen/DAGISelMatcherOpt.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -191,34 +191,10 @@ static Matcher *FindNodeWithKind(Matcher *M, Matcher::KindTy Kind) {
return nullptr;
}

/// FactorNodes - Turn matches like this:
/// Scope
/// OPC_CheckType i32
/// ABC
/// OPC_CheckType i32
/// XYZ
/// into:
/// OPC_CheckType i32
/// Scope
/// ABC
/// XYZ
///
static void FactorNodes(std::unique_ptr<Matcher> &InputMatcherPtr) {
// Look for a push node. Iterates instead of recurses to reduce stack usage.
ScopeMatcher *Scope = nullptr;
std::unique_ptr<Matcher> *RebindableMatcherPtr = &InputMatcherPtr;
while (!Scope) {
// If we reached the end of the chain, we're done.
Matcher *N = RebindableMatcherPtr->get();
if (!N)
return;

// If this is not a push node, just scan for one.
Scope = dyn_cast<ScopeMatcher>(N);
if (!Scope)
RebindableMatcherPtr = &(N->getNextPtr());
}
std::unique_ptr<Matcher> &MatcherPtr = *RebindableMatcherPtr;
static void FactorNodes(std::unique_ptr<Matcher> &InputMatcherPtr);

static void FactorScope(std::unique_ptr<Matcher> &MatcherPtr) {
ScopeMatcher *Scope = cast<ScopeMatcher>(MatcherPtr.get());

// Okay, pull together the children of the scope node into a vector so we can
// inspect it more easily.
Expand Down Expand Up @@ -353,7 +329,7 @@ static void FactorNodes(std::unique_ptr<Matcher> &InputMatcherPtr) {
Shared->setNext(new ScopeMatcher(std::move(EqualMatchers)));

// Recursively factor the newly created node.
FactorNodes(Shared->getNextPtr());
FactorScope(Shared->getNextPtr());
}

// Put the new Matcher where we started in OptionsToMatch.
Expand Down Expand Up @@ -470,7 +446,7 @@ static void FactorNodes(std::unique_ptr<Matcher> &InputMatcherPtr) {
for (auto &M : Cases) {
if (ScopeMatcher *SM = dyn_cast<ScopeMatcher>(M.second)) {
std::unique_ptr<Matcher> Scope(SM);
FactorNodes(Scope);
FactorScope(Scope);
M.second = Scope.release();
assert(M.second && "null matcher");
}
Expand All @@ -492,6 +468,31 @@ static void FactorNodes(std::unique_ptr<Matcher> &InputMatcherPtr) {
Scope->resetChild(i, OptionsToMatch[i]);
}

/// FactorNodes - Turn matches like this:
/// Scope
/// OPC_CheckType i32
/// ABC
/// OPC_CheckType i32
/// XYZ
/// into:
/// OPC_CheckType i32
/// Scope
/// ABC
/// XYZ
///
static void FactorNodes(std::unique_ptr<Matcher> &InputMatcherPtr) {
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@arsenm arsenm Feb 3, 2025

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I don't see why this is referencing unique_ptr at all. This could be done in terms of Matcher* or Matcher&

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@topperc topperc Feb 3, 2025

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The code change the contents of the unique_ptr by calling unique_ptr::reset in several places. It replaces the ScopeMatcher with a SwitchOpcodeMatcher/SwitchType matcher by changing what the owner of ScopeMatcher is pointing to. This requires being able to modify the unique_ptr inside the owner.

// Look for a scope matcher. Iterates instead of recurses to reduce stack
// usage.
std::unique_ptr<Matcher> *MatcherPtr = &InputMatcherPtr;
do {
if (isa<ScopeMatcher>(*MatcherPtr))
return FactorScope(*MatcherPtr);

// If this is not a scope matcher, go to the next node.
MatcherPtr = &(MatcherPtr->get()->getNextPtr());
} while (MatcherPtr->get());
}

void llvm::OptimizeMatcher(std::unique_ptr<Matcher> &MatcherPtr,
const CodeGenDAGPatterns &CGP) {
ContractNodes(MatcherPtr, CGP);
Expand Down