utils/TableGen/DAGISelMatcherOpt.cpp

   1 //===- DAGISelMatcherOpt.cpp - Optimize a DAG Matcher ---------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the DAG Matcher optimizer.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "DAGISelMatcher.h"
  15 using namespace llvm;
  16
  17 static void ContractNodes(OwningPtr<MatcherNode> &Matcher) {
  18   // If we reached the end of the chain, we're done.
  19   MatcherNode *N = Matcher.get();
  20   if (N == 0) return;
  21
  22   // If we have a push node, walk down both edges.
  23   if (PushMatcherNode *Push = dyn_cast<PushMatcherNode>(N))
  24     ContractNodes(Push->getFailurePtr());
  25
  26   // If we found a movechild node with a node that comes in a 'foochild' form,
  27   // transform it.
  28   if (MoveChildMatcherNode *MC = dyn_cast<MoveChildMatcherNode>(N)) {
  29     if (RecordMatcherNode *RM = dyn_cast<RecordMatcherNode>(MC->getNext())) {
  30       MatcherNode *New
  31         = new RecordChildMatcherNode(MC->getChildNo(), RM->getWhatFor());
  32       New->setNext(Matcher.take());
  33       Matcher.reset(New);
  34       MC->setNext(RM->takeNext());
  35       return ContractNodes(Matcher);
  36     }
  37   }
  38
  39   if (MoveChildMatcherNode *MC = dyn_cast<MoveChildMatcherNode>(N))
  40     if (MoveParentMatcherNode *MP =
  41           dyn_cast<MoveParentMatcherNode>(MC->getNext())) {
  42       Matcher.reset(MP->takeNext());
  43       return ContractNodes(Matcher);
  44     }
  45
  46   ContractNodes(N->getNextPtr());
  47 }
  48
  49
  50 MatcherNode *llvm::OptimizeMatcher(MatcherNode *Matcher) {
  51   OwningPtr<MatcherNode> MatcherPtr(Matcher);
  52   ContractNodes(MatcherPtr);
  53   return MatcherPtr.take();
  54 }