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cfe2eab744
SwitchOpcodeMatcher) and have DAGISelMatcherOpt form it. This speeds up selection, particularly for X86 which has lots of variants of instructions with only type differences. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97645 91177308-0d34-0410-b5e6-96231b3b80d8
436 lines
16 KiB
C++
436 lines
16 KiB
C++
//===- DAGISelMatcherOpt.cpp - Optimize a DAG Matcher ---------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the DAG Matcher optimizer.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "isel-opt"
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#include "DAGISelMatcher.h"
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#include "CodeGenDAGPatterns.h"
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#include "llvm/ADT/DenseSet.h"
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#include "llvm/ADT/StringSet.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include <vector>
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using namespace llvm;
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/// ContractNodes - Turn multiple matcher node patterns like 'MoveChild+Record'
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/// into single compound nodes like RecordChild.
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static void ContractNodes(OwningPtr<Matcher> &MatcherPtr,
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const CodeGenDAGPatterns &CGP) {
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// If we reached the end of the chain, we're done.
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Matcher *N = MatcherPtr.get();
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if (N == 0) return;
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// If we have a scope node, walk down all of the children.
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if (ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N)) {
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for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
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OwningPtr<Matcher> Child(Scope->takeChild(i));
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ContractNodes(Child, CGP);
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Scope->resetChild(i, Child.take());
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}
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return;
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}
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// If we found a movechild node with a node that comes in a 'foochild' form,
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// transform it.
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if (MoveChildMatcher *MC = dyn_cast<MoveChildMatcher>(N)) {
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Matcher *New = 0;
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if (RecordMatcher *RM = dyn_cast<RecordMatcher>(MC->getNext()))
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New = new RecordChildMatcher(MC->getChildNo(), RM->getWhatFor(),
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RM->getResultNo());
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if (CheckTypeMatcher *CT= dyn_cast<CheckTypeMatcher>(MC->getNext()))
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New = new CheckChildTypeMatcher(MC->getChildNo(), CT->getType());
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if (New) {
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// Insert the new node.
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New->setNext(MatcherPtr.take());
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MatcherPtr.reset(New);
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// Remove the old one.
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MC->setNext(MC->getNext()->takeNext());
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return ContractNodes(MatcherPtr, CGP);
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}
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}
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// Zap movechild -> moveparent.
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if (MoveChildMatcher *MC = dyn_cast<MoveChildMatcher>(N))
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if (MoveParentMatcher *MP =
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dyn_cast<MoveParentMatcher>(MC->getNext())) {
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MatcherPtr.reset(MP->takeNext());
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return ContractNodes(MatcherPtr, CGP);
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}
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// Turn EmitNode->MarkFlagResults->CompleteMatch into
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// MarkFlagResults->EmitNode->CompleteMatch when we can to encourage
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// MorphNodeTo formation. This is safe because MarkFlagResults never refers
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// to the root of the pattern.
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if (isa<EmitNodeMatcher>(N) && isa<MarkFlagResultsMatcher>(N->getNext()) &&
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isa<CompleteMatchMatcher>(N->getNext()->getNext())) {
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// Unlink the two nodes from the list.
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Matcher *EmitNode = MatcherPtr.take();
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Matcher *MFR = EmitNode->takeNext();
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Matcher *Tail = MFR->takeNext();
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// Relink them.
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MatcherPtr.reset(MFR);
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MFR->setNext(EmitNode);
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EmitNode->setNext(Tail);
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return ContractNodes(MatcherPtr, CGP);
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}
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// Turn EmitNode->CompleteMatch into MorphNodeTo if we can.
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if (EmitNodeMatcher *EN = dyn_cast<EmitNodeMatcher>(N))
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if (CompleteMatchMatcher *CM =
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dyn_cast<CompleteMatchMatcher>(EN->getNext())) {
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// We can only use MorphNodeTo if the result values match up.
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unsigned RootResultFirst = EN->getFirstResultSlot();
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bool ResultsMatch = true;
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for (unsigned i = 0, e = CM->getNumResults(); i != e; ++i)
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if (CM->getResult(i) != RootResultFirst+i)
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ResultsMatch = false;
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// If the selected node defines a subset of the flag/chain results, we
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// can't use MorphNodeTo. For example, we can't use MorphNodeTo if the
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// matched pattern has a chain but the root node doesn't.
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const PatternToMatch &Pattern = CM->getPattern();
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if (!EN->hasChain() &&
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Pattern.getSrcPattern()->NodeHasProperty(SDNPHasChain, CGP))
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ResultsMatch = false;
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// If the matched node has a flag and the output root doesn't, we can't
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// use MorphNodeTo.
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//
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// NOTE: Strictly speaking, we don't have to check for the flag here
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// because the code in the pattern generator doesn't handle it right. We
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// do it anyway for thoroughness.
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if (!EN->hasOutFlag() &&
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Pattern.getSrcPattern()->NodeHasProperty(SDNPOutFlag, CGP))
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ResultsMatch = false;
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// If the root result node defines more results than the source root node
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// *and* has a chain or flag input, then we can't match it because it
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// would end up replacing the extra result with the chain/flag.
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#if 0
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if ((EN->hasFlag() || EN->hasChain()) &&
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EN->getNumNonChainFlagVTs() > ... need to get no results reliably ...)
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ResultMatch = false;
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#endif
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if (ResultsMatch) {
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const SmallVectorImpl<MVT::SimpleValueType> &VTs = EN->getVTList();
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const SmallVectorImpl<unsigned> &Operands = EN->getOperandList();
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MatcherPtr.reset(new MorphNodeToMatcher(EN->getOpcodeName(),
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VTs.data(), VTs.size(),
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Operands.data(),Operands.size(),
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EN->hasChain(), EN->hasInFlag(),
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EN->hasOutFlag(),
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EN->hasMemRefs(),
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EN->getNumFixedArityOperands(),
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Pattern));
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return;
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}
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// FIXME2: Kill off all the SelectionDAG::SelectNodeTo and getMachineNode
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// variants.
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}
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ContractNodes(N->getNextPtr(), CGP);
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// If we have a CheckType/CheckChildType/Record node followed by a
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// CheckOpcode, invert the two nodes. We prefer to do structural checks
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// before type checks, as this opens opportunities for factoring on targets
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// like X86 where many operations are valid on multiple types.
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if ((isa<CheckTypeMatcher>(N) || isa<CheckChildTypeMatcher>(N) ||
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isa<RecordMatcher>(N)) &&
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isa<CheckOpcodeMatcher>(N->getNext())) {
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// Unlink the two nodes from the list.
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Matcher *CheckType = MatcherPtr.take();
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Matcher *CheckOpcode = CheckType->takeNext();
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Matcher *Tail = CheckOpcode->takeNext();
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// Relink them.
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MatcherPtr.reset(CheckOpcode);
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CheckOpcode->setNext(CheckType);
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CheckType->setNext(Tail);
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return ContractNodes(MatcherPtr, CGP);
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}
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}
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/// SinkPatternPredicates - Pattern predicates can be checked at any level of
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/// the matching tree. The generator dumps them at the top level of the pattern
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/// though, which prevents factoring from being able to see past them. This
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/// optimization sinks them as far down into the pattern as possible.
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///
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/// Conceptually, we'd like to sink these predicates all the way to the last
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/// matcher predicate in the series. However, it turns out that some
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/// ComplexPatterns have side effects on the graph, so we really don't want to
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/// run a the complex pattern if the pattern predicate will fail. For this
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/// reason, we refuse to sink the pattern predicate past a ComplexPattern.
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///
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static void SinkPatternPredicates(OwningPtr<Matcher> &MatcherPtr) {
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// Recursively scan for a PatternPredicate.
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// If we reached the end of the chain, we're done.
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Matcher *N = MatcherPtr.get();
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if (N == 0) return;
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// Walk down all members of a scope node.
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if (ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N)) {
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for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
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OwningPtr<Matcher> Child(Scope->takeChild(i));
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SinkPatternPredicates(Child);
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Scope->resetChild(i, Child.take());
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}
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return;
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}
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// If this node isn't a CheckPatternPredicateMatcher we keep scanning until
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// we find one.
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CheckPatternPredicateMatcher *CPPM =dyn_cast<CheckPatternPredicateMatcher>(N);
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if (CPPM == 0)
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return SinkPatternPredicates(N->getNextPtr());
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// Ok, we found one, lets try to sink it. Check if we can sink it past the
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// next node in the chain. If not, we won't be able to change anything and
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// might as well bail.
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if (!CPPM->getNext()->isSafeToReorderWithPatternPredicate())
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return;
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// Okay, we know we can sink it past at least one node. Unlink it from the
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// chain and scan for the new insertion point.
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MatcherPtr.take(); // Don't delete CPPM.
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MatcherPtr.reset(CPPM->takeNext());
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N = MatcherPtr.get();
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while (N->getNext()->isSafeToReorderWithPatternPredicate())
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N = N->getNext();
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// At this point, we want to insert CPPM after N.
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CPPM->setNext(N->takeNext());
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N->setNext(CPPM);
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}
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/// FactorNodes - Turn matches like this:
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/// Scope
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/// OPC_CheckType i32
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/// ABC
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/// OPC_CheckType i32
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/// XYZ
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/// into:
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/// OPC_CheckType i32
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/// Scope
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/// ABC
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/// XYZ
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///
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static void FactorNodes(OwningPtr<Matcher> &MatcherPtr) {
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// If we reached the end of the chain, we're done.
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Matcher *N = MatcherPtr.get();
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if (N == 0) return;
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// If this is not a push node, just scan for one.
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ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N);
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if (Scope == 0)
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return FactorNodes(N->getNextPtr());
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// Okay, pull together the children of the scope node into a vector so we can
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// inspect it more easily. While we're at it, bucket them up by the hash
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// code of their first predicate.
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SmallVector<Matcher*, 32> OptionsToMatch;
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for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
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// Factor the subexpression.
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OwningPtr<Matcher> Child(Scope->takeChild(i));
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FactorNodes(Child);
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if (Matcher *N = Child.take())
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OptionsToMatch.push_back(N);
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}
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SmallVector<Matcher*, 32> NewOptionsToMatch;
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// Loop over options to match, merging neighboring patterns with identical
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// starting nodes into a shared matcher.
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for (unsigned OptionIdx = 0, e = OptionsToMatch.size(); OptionIdx != e;) {
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// Find the set of matchers that start with this node.
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Matcher *Optn = OptionsToMatch[OptionIdx++];
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if (OptionIdx == e) {
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NewOptionsToMatch.push_back(Optn);
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continue;
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}
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// See if the next option starts with the same matcher. If the two
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// neighbors *do* start with the same matcher, we can factor the matcher out
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// of at least these two patterns. See what the maximal set we can merge
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// together is.
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SmallVector<Matcher*, 8> EqualMatchers;
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EqualMatchers.push_back(Optn);
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// Factor all of the known-equal matchers after this one into the same
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// group.
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while (OptionIdx != e && OptionsToMatch[OptionIdx]->isEqual(Optn))
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EqualMatchers.push_back(OptionsToMatch[OptionIdx++]);
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// If we found a non-equal matcher, see if it is contradictory with the
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// current node. If so, we know that the ordering relation between the
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// current sets of nodes and this node don't matter. Look past it to see if
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// we can merge anything else into this matching group.
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unsigned Scan = OptionIdx;
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while (1) {
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while (Scan != e && Optn->isContradictory(OptionsToMatch[Scan]))
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++Scan;
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// Ok, we found something that isn't known to be contradictory. If it is
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// equal, we can merge it into the set of nodes to factor, if not, we have
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// to cease factoring.
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if (Scan == e || !Optn->isEqual(OptionsToMatch[Scan])) break;
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// If is equal after all, add the option to EqualMatchers and remove it
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// from OptionsToMatch.
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EqualMatchers.push_back(OptionsToMatch[Scan]);
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OptionsToMatch.erase(OptionsToMatch.begin()+Scan);
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--e;
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}
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if (Scan != e &&
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// Don't print it's obvious nothing extra could be merged anyway.
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Scan+1 != e) {
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DEBUG(errs() << "Couldn't merge this:\n";
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Optn->print(errs(), 4);
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errs() << "into this:\n";
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OptionsToMatch[Scan]->print(errs(), 4);
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if (Scan+1 != e)
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OptionsToMatch[Scan+1]->printOne(errs());
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if (Scan+2 < e)
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OptionsToMatch[Scan+2]->printOne(errs());
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errs() << "\n");
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}
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// If we only found one option starting with this matcher, no factoring is
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// possible.
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if (EqualMatchers.size() == 1) {
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NewOptionsToMatch.push_back(EqualMatchers[0]);
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continue;
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}
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// Factor these checks by pulling the first node off each entry and
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// discarding it. Take the first one off the first entry to reuse.
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Matcher *Shared = Optn;
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Optn = Optn->takeNext();
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EqualMatchers[0] = Optn;
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// Remove and delete the first node from the other matchers we're factoring.
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for (unsigned i = 1, e = EqualMatchers.size(); i != e; ++i) {
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Matcher *Tmp = EqualMatchers[i]->takeNext();
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delete EqualMatchers[i];
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EqualMatchers[i] = Tmp;
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}
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Shared->setNext(new ScopeMatcher(&EqualMatchers[0], EqualMatchers.size()));
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// Recursively factor the newly created node.
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FactorNodes(Shared->getNextPtr());
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NewOptionsToMatch.push_back(Shared);
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}
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// If we're down to a single pattern to match, then we don't need this scope
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// anymore.
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if (NewOptionsToMatch.size() == 1) {
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MatcherPtr.reset(NewOptionsToMatch[0]);
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return;
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}
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if (NewOptionsToMatch.empty()) {
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MatcherPtr.reset(0);
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return;
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}
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// If our factoring failed (didn't achieve anything) see if we can simplify in
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// other ways.
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// Check to see if all of the leading entries are now opcode checks. If so,
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// we can convert this Scope to be a OpcodeSwitch instead.
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bool AllOpcodeChecks = true, AllTypeChecks = true;
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for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
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if (!isa<CheckOpcodeMatcher>(NewOptionsToMatch[i])) {
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#if 0
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if (i > 3 && AllOpcodeChecks) {
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errs() << "FAILING OPC #" << i << "\n";
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NewOptionsToMatch[i]->dump();
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}
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#endif
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AllOpcodeChecks = false;
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}
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if (!isa<CheckTypeMatcher>(NewOptionsToMatch[i]) ||
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// iPTR checks could alias any other case without us knowing, don't
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// bother with them.
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cast<CheckTypeMatcher>(NewOptionsToMatch[i])->getType() == MVT::iPTR) {
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#if 0
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if (i > 3 && AllTypeChecks) {
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errs() << "FAILING TYPE #" << i << "\n";
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NewOptionsToMatch[i]->dump();
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}
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#endif
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AllTypeChecks = false;
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}
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}
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// TODO: Can also do CheckChildNType.
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// If all the options are CheckOpcode's, we can form the SwitchOpcode, woot.
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if (AllOpcodeChecks) {
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StringSet<> Opcodes;
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SmallVector<std::pair<const SDNodeInfo*, Matcher*>, 8> Cases;
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for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
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CheckOpcodeMatcher *COM = cast<CheckOpcodeMatcher>(NewOptionsToMatch[i]);
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assert(Opcodes.insert(COM->getOpcode().getEnumName()) &&
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"Duplicate opcodes not factored?");
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Cases.push_back(std::make_pair(&COM->getOpcode(), COM->getNext()));
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}
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MatcherPtr.reset(new SwitchOpcodeMatcher(&Cases[0], Cases.size()));
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return;
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}
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// If all the options are CheckType's, we can form the SwitchType, woot.
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if (AllTypeChecks) {
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DenseSet<unsigned> Types;
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SmallVector<std::pair<MVT::SimpleValueType, Matcher*>, 8> Cases;
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for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
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CheckTypeMatcher *CTM = cast<CheckTypeMatcher>(NewOptionsToMatch[i]);
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assert(Types.insert(CTM->getType()).second &&
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"Duplicate types not factored?");
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Cases.push_back(std::make_pair(CTM->getType(), CTM->getNext()));
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}
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MatcherPtr.reset(new SwitchTypeMatcher(&Cases[0], Cases.size()));
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return;
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}
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// Reassemble the Scope node with the adjusted children.
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Scope->setNumChildren(NewOptionsToMatch.size());
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for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i)
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Scope->resetChild(i, NewOptionsToMatch[i]);
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}
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Matcher *llvm::OptimizeMatcher(Matcher *TheMatcher,
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const CodeGenDAGPatterns &CGP) {
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OwningPtr<Matcher> MatcherPtr(TheMatcher);
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ContractNodes(MatcherPtr, CGP);
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SinkPatternPredicates(MatcherPtr);
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FactorNodes(MatcherPtr);
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return MatcherPtr.take();
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}
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