472 lines
17 KiB
C++
472 lines
17 KiB
C++
//===- DAGISelMatcherOpt.cpp - Optimize a DAG Matcher ---------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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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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#include "DAGISelMatcher.h"
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#include "CodeGenDAGPatterns.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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using namespace llvm;
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#define DEBUG_TYPE "isel-opt"
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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(std::unique_ptr<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) 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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std::unique_ptr<Matcher> Child(Scope->takeChild(i));
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ContractNodes(Child, CGP);
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Scope->resetChild(i, Child.release());
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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 = nullptr;
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if (RecordMatcher *RM = dyn_cast<RecordMatcher>(MC->getNext()))
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if (MC->getChildNo() < 8) // Only have RecordChild0...7
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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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if (MC->getChildNo() < 8 && // Only have CheckChildType0...7
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CT->getResNo() == 0) // CheckChildType checks res #0
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New = new CheckChildTypeMatcher(MC->getChildNo(), CT->getType());
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if (CheckSameMatcher *CS = dyn_cast<CheckSameMatcher>(MC->getNext()))
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if (MC->getChildNo() < 4) // Only have CheckChildSame0...3
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New = new CheckChildSameMatcher(MC->getChildNo(), CS->getMatchNumber());
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if (CheckIntegerMatcher *CI = dyn_cast<CheckIntegerMatcher>(MC->getNext()))
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if (MC->getChildNo() < 5) // Only have CheckChildInteger0...4
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New = new CheckChildIntegerMatcher(MC->getChildNo(), CI->getValue());
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if (auto *CCC = dyn_cast<CheckCondCodeMatcher>(MC->getNext()))
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if (MC->getChildNo() == 2) // Only have CheckChild2CondCode
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New = new CheckChild2CondCodeMatcher(CCC->getCondCodeName());
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if (New) {
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// Insert the new node.
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New->setNext(MatcherPtr.release());
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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->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 glue/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 glue 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 glue 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(SDNPOutGlue, 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 glue input, then we can't match it because it
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// would end up replacing the extra result with the chain/glue.
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#if 0
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if ((EN->hasGlue() || EN->hasChain()) &&
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EN->getNumNonChainGlueVTs() > ... 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, Operands,
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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.release();
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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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/// FindNodeWithKind - Scan a series of matchers looking for a matcher with a
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/// specified kind. Return null if we didn't find one otherwise return the
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/// matcher.
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static Matcher *FindNodeWithKind(Matcher *M, Matcher::KindTy Kind) {
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for (; M; M = M->getNext())
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if (M->getKind() == Kind)
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return M;
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return nullptr;
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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(std::unique_ptr<Matcher> &InputMatcherPtr) {
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// Look for a push node. Iterates instead of recurses to reduce stack usage.
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ScopeMatcher *Scope = nullptr;
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std::unique_ptr<Matcher> *RebindableMatcherPtr = &InputMatcherPtr;
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while (!Scope) {
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// If we reached the end of the chain, we're done.
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Matcher *N = RebindableMatcherPtr->get();
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if (!N) return;
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// If this is not a push node, just scan for one.
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Scope = dyn_cast<ScopeMatcher>(N);
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if (!Scope)
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RebindableMatcherPtr = &(N->getNextPtr());
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}
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std::unique_ptr<Matcher> &MatcherPtr = *RebindableMatcherPtr;
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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.
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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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std::unique_ptr<Matcher> Child(Scope->takeChild(i));
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FactorNodes(Child);
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if (Child) {
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// If the child is a ScopeMatcher we can just merge its contents.
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if (auto *SM = dyn_cast<ScopeMatcher>(Child.get())) {
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for (unsigned j = 0, e = SM->getNumChildren(); j != e; ++j)
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OptionsToMatch.push_back(SM->takeChild(j));
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} else {
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OptionsToMatch.push_back(Child.release());
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}
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}
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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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// If we ran out of stuff to scan, we're done.
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if (Scan == e) break;
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Matcher *ScanMatcher = OptionsToMatch[Scan];
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// If we found an entry that matches out matcher, merge it into the set to
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// handle.
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if (Optn->isEqual(ScanMatcher)) {
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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(ScanMatcher);
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OptionsToMatch.erase(OptionsToMatch.begin()+Scan);
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--e;
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continue;
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}
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// If the option we're checking for contradicts the start of the list,
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// skip over it.
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if (Optn->isContradictory(ScanMatcher)) {
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++Scan;
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continue;
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}
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// If we're scanning for a simple node, see if it occurs later in the
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// sequence. If so, and if we can move it up, it might be contradictory
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// or the same as what we're looking for. If so, reorder it.
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if (Optn->isSimplePredicateOrRecordNode()) {
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Matcher *M2 = FindNodeWithKind(ScanMatcher, Optn->getKind());
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if (M2 && M2 != ScanMatcher &&
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M2->canMoveBefore(ScanMatcher) &&
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(M2->isEqual(Optn) || M2->isContradictory(Optn))) {
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Matcher *MatcherWithoutM2 = ScanMatcher->unlinkNode(M2);
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M2->setNext(MatcherWithoutM2);
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OptionsToMatch[Scan] = M2;
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continue;
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}
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}
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// Otherwise, we don't know how to handle this entry, we have to bail.
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break;
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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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LLVM_DEBUG(errs() << "Couldn't merge this:\n"; 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) OptionsToMatch[Scan + 1]->printOne(errs());
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if (Scan + 2 < e) 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));
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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();
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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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// Check to see if this breaks a series of CheckOpcodeMatchers.
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if (AllOpcodeChecks &&
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!isa<CheckOpcodeMatcher>(NewOptionsToMatch[i])) {
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#if 0
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if (i > 3) {
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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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// Check to see if this breaks a series of CheckTypeMatcher's.
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if (AllTypeChecks) {
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CheckTypeMatcher *CTM =
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cast_or_null<CheckTypeMatcher>(FindNodeWithKind(NewOptionsToMatch[i],
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Matcher::CheckType));
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if (!CTM ||
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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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CTM->getType() == MVT::iPTR ||
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// SwitchType only works for result #0.
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CTM->getResNo() != 0 ||
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// If the CheckType isn't at the start of the list, see if we can move
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// it there.
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!CTM->canMoveBefore(NewOptionsToMatch[i])) {
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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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}
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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()).second &&
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"Duplicate opcodes not factored?");
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Cases.push_back(std::make_pair(&COM->getOpcode(), COM->takeNext()));
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delete COM;
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}
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MatcherPtr.reset(new SwitchOpcodeMatcher(Cases));
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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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DenseMap<unsigned, unsigned> TypeEntry;
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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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Matcher* M = FindNodeWithKind(NewOptionsToMatch[i], Matcher::CheckType);
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assert(M && isa<CheckTypeMatcher>(M) && "Unknown Matcher type");
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auto *CTM = cast<CheckTypeMatcher>(M);
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Matcher *MatcherWithoutCTM = NewOptionsToMatch[i]->unlinkNode(CTM);
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MVT::SimpleValueType CTMTy = CTM->getType();
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delete CTM;
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unsigned &Entry = TypeEntry[CTMTy];
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if (Entry != 0) {
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// If we have unfactored duplicate types, then we should factor them.
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Matcher *PrevMatcher = Cases[Entry-1].second;
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if (ScopeMatcher *SM = dyn_cast<ScopeMatcher>(PrevMatcher)) {
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SM->setNumChildren(SM->getNumChildren()+1);
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SM->resetChild(SM->getNumChildren()-1, MatcherWithoutCTM);
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continue;
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}
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Matcher *Entries[2] = { PrevMatcher, MatcherWithoutCTM };
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Cases[Entry-1].second = new ScopeMatcher(Entries);
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continue;
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}
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Entry = Cases.size()+1;
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Cases.push_back(std::make_pair(CTMTy, MatcherWithoutCTM));
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}
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// Make sure we recursively factor any scopes we may have created.
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for (auto &M : Cases) {
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if (ScopeMatcher *SM = dyn_cast<ScopeMatcher>(M.second)) {
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std::unique_ptr<Matcher> Scope(SM);
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FactorNodes(Scope);
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M.second = Scope.release();
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assert(M.second && "null matcher");
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}
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}
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if (Cases.size() != 1) {
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MatcherPtr.reset(new SwitchTypeMatcher(Cases));
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} else {
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// If we factored and ended up with one case, create it now.
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MatcherPtr.reset(new CheckTypeMatcher(Cases[0].first, 0));
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MatcherPtr->setNext(Cases[0].second);
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}
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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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void
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llvm::OptimizeMatcher(std::unique_ptr<Matcher> &MatcherPtr,
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const CodeGenDAGPatterns &CGP) {
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ContractNodes(MatcherPtr, CGP);
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FactorNodes(MatcherPtr);
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}
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