llvm/utils/TableGen/DAGISelMatcherOpt.cpp
2010-02-25 01:57:41 +00:00

84 lines
2.7 KiB
C++

//===- DAGISelMatcherOpt.cpp - Optimize a DAG Matcher ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the DAG Matcher optimizer.
//
//===----------------------------------------------------------------------===//
#include "DAGISelMatcher.h"
using namespace llvm;
static void ContractNodes(OwningPtr<MatcherNode> &MatcherPtr) {
// If we reached the end of the chain, we're done.
MatcherNode *N = MatcherPtr.get();
if (N == 0) return;
// If we have a scope node, walk down both edges.
if (ScopeMatcherNode *Push = dyn_cast<ScopeMatcherNode>(N))
ContractNodes(Push->getCheckPtr());
// If we found a movechild node with a node that comes in a 'foochild' form,
// transform it.
if (MoveChildMatcherNode *MC = dyn_cast<MoveChildMatcherNode>(N)) {
MatcherNode *New = 0;
if (RecordMatcherNode *RM = dyn_cast<RecordMatcherNode>(MC->getNext()))
New = new RecordChildMatcherNode(MC->getChildNo(), RM->getWhatFor());
if (CheckTypeMatcherNode *CT= dyn_cast<CheckTypeMatcherNode>(MC->getNext()))
New = new CheckChildTypeMatcherNode(MC->getChildNo(), CT->getType());
if (New) {
// Insert the new node.
New->setNext(MatcherPtr.take());
MatcherPtr.reset(New);
// Remove the old one.
MC->setNext(MC->getNext()->takeNext());
return ContractNodes(MatcherPtr);
}
}
if (MoveChildMatcherNode *MC = dyn_cast<MoveChildMatcherNode>(N))
if (MoveParentMatcherNode *MP =
dyn_cast<MoveParentMatcherNode>(MC->getNext())) {
MatcherPtr.reset(MP->takeNext());
return ContractNodes(MatcherPtr);
}
ContractNodes(N->getNextPtr());
}
static void FactorNodes(OwningPtr<MatcherNode> &MatcherPtr) {
// If we reached the end of the chain, we're done.
MatcherNode *N = MatcherPtr.get();
if (N == 0) return;
// If this is not a push node, just scan for one.
if (!isa<ScopeMatcherNode>(N))
return FactorNodes(N->getNextPtr());
// Okay, pull together the series of linear push nodes into a vector so we can
// inspect it more easily.
SmallVector<MatcherNode*, 32> OptionsToMatch;
MatcherNode *CurNode = N;
for (; ScopeMatcherNode *PMN = dyn_cast<ScopeMatcherNode>(CurNode);
CurNode = PMN->getNext())
OptionsToMatch.push_back(PMN->getCheck());
OptionsToMatch.push_back(CurNode);
}
MatcherNode *llvm::OptimizeMatcher(MatcherNode *Matcher) {
OwningPtr<MatcherNode> MatcherPtr(Matcher);
ContractNodes(MatcherPtr);
FactorNodes(MatcherPtr);
return MatcherPtr.take();
}