llvm-6502/utils/TableGen/DAGISelMatcherGen.cpp
Chris Lattner da272d1a70 Check in the first big step of rewriting DAGISelEmitter to
produce a table based matcher instead of gobs of C++ Code.

Though it's not done yet, the shrinkage seems promising,
the table for the X86 ISel is 75K and still has a lot of 
optimization to come (compare to the ~1.5M of .o generated
the old way, much of which will go away).

The code is currently disabled by default (the #if 0 in
DAGISelEmitter.cpp).  When enabled it generates a dead
SelectCode2 function in the DAGISel Header which will
eventually replace SelectCode.

There is still a lot of stuff left to do, which are
documented with a trail of FIXMEs.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96215 91177308-0d34-0410-b5e6-96231b3b80d8
2010-02-15 08:04:42 +00:00

288 lines
10 KiB
C++

//===- DAGISelMatcherGen.cpp - Matcher generator --------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "DAGISelMatcher.h"
#include "CodeGenDAGPatterns.h"
#include "Record.h"
#include "llvm/ADT/StringMap.h"
using namespace llvm;
namespace {
class MatcherGen {
const PatternToMatch &Pattern;
const CodeGenDAGPatterns &CGP;
/// PatWithNoTypes - This is a clone of Pattern.getSrcPattern() that starts
/// out with all of the types removed. This allows us to insert type checks
/// as we scan the tree.
TreePatternNode *PatWithNoTypes;
/// VariableMap - A map from variable names ('$dst') to the recorded operand
/// number that they were captured as. These are biased by 1 to make
/// insertion easier.
StringMap<unsigned> VariableMap;
unsigned NextRecordedOperandNo;
MatcherNodeWithChild *Matcher;
MatcherNodeWithChild *CurPredicate;
public:
MatcherGen(const PatternToMatch &pattern, const CodeGenDAGPatterns &cgp);
~MatcherGen() {
delete PatWithNoTypes;
}
void EmitMatcherCode();
MatcherNodeWithChild *GetMatcher() const { return Matcher; }
MatcherNodeWithChild *GetCurPredicate() const { return CurPredicate; }
private:
void AddMatcherNode(MatcherNodeWithChild *NewNode);
void InferPossibleTypes();
void EmitMatchCode(const TreePatternNode *N, TreePatternNode *NodeNoTypes);
void EmitLeafMatchCode(const TreePatternNode *N);
void EmitOperatorMatchCode(const TreePatternNode *N,
TreePatternNode *NodeNoTypes);
};
} // end anon namespace.
MatcherGen::MatcherGen(const PatternToMatch &pattern,
const CodeGenDAGPatterns &cgp)
: Pattern(pattern), CGP(cgp), NextRecordedOperandNo(0),
Matcher(0), CurPredicate(0) {
// We need to produce the matcher tree for the patterns source pattern. To do
// this we need to match the structure as well as the types. To do the type
// matching, we want to figure out the fewest number of type checks we need to
// emit. For example, if there is only one integer type supported by a
// target, there should be no type comparisons at all for integer patterns!
//
// To figure out the fewest number of type checks needed, clone the pattern,
// remove the types, then perform type inference on the pattern as a whole.
// If there are unresolved types, emit an explicit check for those types,
// apply the type to the tree, then rerun type inference. Iterate until all
// types are resolved.
//
PatWithNoTypes = Pattern.getSrcPattern()->clone();
PatWithNoTypes->RemoveAllTypes();
// If there are types that are manifestly known, infer them.
InferPossibleTypes();
}
/// InferPossibleTypes - As we emit the pattern, we end up generating type
/// checks and applying them to the 'PatWithNoTypes' tree. As we do this, we
/// want to propagate implied types as far throughout the tree as possible so
/// that we avoid doing redundant type checks. This does the type propagation.
void MatcherGen::InferPossibleTypes() {
// TP - Get *SOME* tree pattern, we don't care which. It is only used for
// diagnostics, which we know are impossible at this point.
TreePattern &TP = *CGP.pf_begin()->second;
try {
bool MadeChange = true;
while (MadeChange)
MadeChange = PatWithNoTypes->ApplyTypeConstraints(TP,
true/*Ignore reg constraints*/);
} catch (...) {
errs() << "Type constraint application shouldn't fail!";
abort();
}
}
/// AddMatcherNode - Add a matcher node to the current graph we're building.
void MatcherGen::AddMatcherNode(MatcherNodeWithChild *NewNode) {
if (CurPredicate != 0)
CurPredicate->setChild(NewNode);
else
Matcher = NewNode;
CurPredicate = NewNode;
}
/// EmitLeafMatchCode - Generate matching code for leaf nodes.
void MatcherGen::EmitLeafMatchCode(const TreePatternNode *N) {
assert(N->isLeaf() && "Not a leaf?");
// Direct match against an integer constant.
if (IntInit *II = dynamic_cast<IntInit*>(N->getLeafValue()))
return AddMatcherNode(new CheckIntegerMatcherNode(II->getValue()));
DefInit *DI = dynamic_cast<DefInit*>(N->getLeafValue());
if (DI == 0) {
errs() << "Unknown leaf kind: " << *DI << "\n";
abort();
}
Record *LeafRec = DI->getDef();
if (// Handle register references. Nothing to do here, they always match.
LeafRec->isSubClassOf("RegisterClass") ||
LeafRec->isSubClassOf("PointerLikeRegClass") ||
LeafRec->isSubClassOf("Register") ||
// Place holder for SRCVALUE nodes. Nothing to do here.
LeafRec->getName() == "srcvalue")
return;
if (LeafRec->isSubClassOf("ValueType"))
return AddMatcherNode(new CheckValueTypeMatcherNode(LeafRec->getName()));
if (LeafRec->isSubClassOf("CondCode"))
return AddMatcherNode(new CheckCondCodeMatcherNode(LeafRec->getName()));
if (LeafRec->isSubClassOf("ComplexPattern")) {
// Handle complex pattern.
const ComplexPattern &CP = CGP.getComplexPattern(LeafRec);
return AddMatcherNode(new CheckComplexPatMatcherNode(CP));
}
errs() << "Unknown leaf kind: " << *N << "\n";
abort();
}
void MatcherGen::EmitOperatorMatchCode(const TreePatternNode *N,
TreePatternNode *NodeNoTypes) {
assert(!N->isLeaf() && "Not an operator?");
const SDNodeInfo &CInfo = CGP.getSDNodeInfo(N->getOperator());
// If this is an 'and R, 1234' where the operation is AND/OR and the RHS is
// a constant without a predicate fn that has more that one bit set, handle
// this as a special case. This is usually for targets that have special
// handling of certain large constants (e.g. alpha with it's 8/16/32-bit
// handling stuff). Using these instructions is often far more efficient
// than materializing the constant. Unfortunately, both the instcombiner
// and the dag combiner can often infer that bits are dead, and thus drop
// them from the mask in the dag. For example, it might turn 'AND X, 255'
// into 'AND X, 254' if it knows the low bit is set. Emit code that checks
// to handle this.
if ((N->getOperator()->getName() == "and" ||
N->getOperator()->getName() == "or") &&
N->getChild(1)->isLeaf() && N->getChild(1)->getPredicateFns().empty()) {
if (IntInit *II = dynamic_cast<IntInit*>(N->getChild(1)->getLeafValue())) {
if (!isPowerOf2_32(II->getValue())) { // Don't bother with single bits.
if (N->getOperator()->getName() == "and")
AddMatcherNode(new CheckAndImmMatcherNode(II->getValue()));
else
AddMatcherNode(new CheckOrImmMatcherNode(II->getValue()));
// Match the LHS of the AND as appropriate.
AddMatcherNode(new MoveChildMatcherNode(0));
EmitMatchCode(N->getChild(0), NodeNoTypes->getChild(0));
AddMatcherNode(new MoveParentMatcherNode());
return;
}
}
}
// Check that the current opcode lines up.
AddMatcherNode(new CheckOpcodeMatcherNode(CInfo.getEnumName()));
// If this node has a chain, then the chain is operand #0 is the SDNode, and
// the child numbers of the node are all offset by one.
unsigned OpNo = 0;
if (N->NodeHasProperty(SDNPHasChain, CGP))
OpNo = 1;
if (N->TreeHasProperty(SDNPHasChain, CGP)) {
// FIXME: Handle Chains with multiple uses etc.
// [ld]
// ^ ^
// | |
// / \---
// / [YY]
// | ^
// [XX]-------|
}
// FIXME: Handle Flags & .hasOneUse()
for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i, ++OpNo) {
// Get the code suitable for matching this child. Move to the child, check
// it then move back to the parent.
AddMatcherNode(new MoveChildMatcherNode(i));
EmitMatchCode(N->getChild(i), NodeNoTypes->getChild(i));
AddMatcherNode(new MoveParentMatcherNode());
}
}
void MatcherGen::EmitMatchCode(const TreePatternNode *N,
TreePatternNode *NodeNoTypes) {
// If N and NodeNoTypes don't agree on a type, then this is a case where we
// need to do a type check. Emit the check, apply the tyep to NodeNoTypes and
// reinfer any correlated types.
if (NodeNoTypes->getExtTypes() != N->getExtTypes()) {
AddMatcherNode(new CheckTypeMatcherNode(N->getTypeNum(0)));
NodeNoTypes->setTypes(N->getExtTypes());
InferPossibleTypes();
}
// If this node has a name associated with it, capture it in VariableMap. If
// we already saw this in the pattern, emit code to verify dagness.
if (!N->getName().empty()) {
unsigned &VarMapEntry = VariableMap[N->getName()];
if (VarMapEntry == 0) {
VarMapEntry = ++NextRecordedOperandNo;
AddMatcherNode(new RecordMatcherNode());
} else {
// If we get here, this is a second reference to a specific name. Since
// we already have checked that the first reference is valid, we don't
// have to recursively match it, just check that it's the same as the
// previously named thing.
AddMatcherNode(new CheckSameMatcherNode(VarMapEntry-1));
return;
}
}
// If there are node predicates for this node, generate their checks.
for (unsigned i = 0, e = N->getPredicateFns().size(); i != e; ++i)
AddMatcherNode(new CheckPredicateMatcherNode(N->getPredicateFns()[i]));
if (N->isLeaf())
EmitLeafMatchCode(N);
else
EmitOperatorMatchCode(N, NodeNoTypes);
}
void MatcherGen::EmitMatcherCode() {
// If the pattern has a predicate on it (e.g. only enabled when a subtarget
// feature is around, do the check).
if (!Pattern.getPredicateCheck().empty())
AddMatcherNode(new
CheckPatternPredicateMatcherNode(Pattern.getPredicateCheck()));
// Emit the matcher for the pattern structure and types.
EmitMatchCode(Pattern.getSrcPattern(), PatWithNoTypes);
}
MatcherNode *llvm::ConvertPatternToMatcher(const PatternToMatch &Pattern,
const CodeGenDAGPatterns &CGP) {
MatcherGen Gen(Pattern, CGP);
// Generate the code for the matcher.
Gen.EmitMatcherCode();
// If the match succeeds, then we generate Pattern.
EmitNodeMatcherNode *Result = new EmitNodeMatcherNode(Pattern);
// Link it into the pattern.
if (MatcherNodeWithChild *Pred = Gen.GetCurPredicate()) {
Pred->setChild(Result);
return Gen.GetMatcher();
}
// Unconditional match.
return Result;
}