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[TableGen] Remove SinkPatternPredicates from the DAG isel matcher optimizer. 

Pattern predicates already appear to be emitted as far down as they can be. The optimization was making no changes on any in-tree target.

llvm-svn: 268705
This commit is contained in:
Craig Topper 2016-05-06 02:37:56 +00:00
parent ac96ea422b
commit b3fb529cc6
1 changed files with 0 additions and 54 deletions
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54
llvm/utils/TableGen/DAGISelMatcherOpt.cpp
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@ -158,59 +158,6 @@ static void ContractNodes(std::unique_ptr<Matcher> &MatcherPtr,
}
}
/// SinkPatternPredicates - Pattern predicates can be checked at any level of
/// the matching tree. The generator dumps them at the top level of the pattern
/// though, which prevents factoring from being able to see past them. This
/// optimization sinks them as far down into the pattern as possible.
///
/// Conceptually, we'd like to sink these predicates all the way to the last
/// matcher predicate in the series. However, it turns out that some
/// ComplexPatterns have side effects on the graph, so we really don't want to
/// run a complex pattern if the pattern predicate will fail. For this
/// reason, we refuse to sink the pattern predicate past a ComplexPattern.
///
static void SinkPatternPredicates(std::unique_ptr<Matcher> &MatcherPtr) {
// Recursively scan for a PatternPredicate.
// If we reached the end of the chain, we're done.
Matcher *N = MatcherPtr.get();
if (!N) return;
// Walk down all members of a scope node.
if (ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N)) {
for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
std::unique_ptr<Matcher> Child(Scope->takeChild(i));
SinkPatternPredicates(Child);
Scope->resetChild(i, Child.release());
}
return;
}
// If this node isn't a CheckPatternPredicateMatcher we keep scanning until
// we find one.
CheckPatternPredicateMatcher *CPPM =dyn_cast<CheckPatternPredicateMatcher>(N);
if (!CPPM)
return SinkPatternPredicates(N->getNextPtr());
// Ok, we found one, lets try to sink it. Check if we can sink it past the
// next node in the chain. If not, we won't be able to change anything and
// might as well bail.
if (!CPPM->getNext()->isSafeToReorderWithPatternPredicate())
return;
// Okay, we know we can sink it past at least one node. Unlink it from the
// chain and scan for the new insertion point.
MatcherPtr.release(); // Don't delete CPPM.
MatcherPtr.reset(CPPM->takeNext());
N = MatcherPtr.get();
while (N->getNext()->isSafeToReorderWithPatternPredicate())
N = N->getNext();
// At this point, we want to insert CPPM after N.
CPPM->setNext(N->takeNext());
N->setNext(CPPM);
}
/// FindNodeWithKind - Scan a series of matchers looking for a matcher with a
/// specified kind. Return null if we didn't find one otherwise return the
/// matcher.
@ -497,6 +444,5 @@ void
llvm::OptimizeMatcher(std::unique_ptr<Matcher> &MatcherPtr,
const CodeGenDAGPatterns &CGP) {
ContractNodes(MatcherPtr, CGP);
SinkPatternPredicates(MatcherPtr);
FactorNodes(MatcherPtr);
}