llvm-6502/utils/TableGen/DAGISelEmitter.cpp
2010-03-19 00:07:20 +00:00

234 lines
8.5 KiB
C++

//===- DAGISelEmitter.cpp - Generate an instruction selector --------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This tablegen backend emits a DAG instruction selector.
//
//===----------------------------------------------------------------------===//
#include "DAGISelEmitter.h"
#include "DAGISelMatcher.h"
#include "Record.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// DAGISelEmitter Helper methods
//
/// getPatternSize - Return the 'size' of this pattern. We want to match large
/// patterns before small ones. This is used to determine the size of a
/// pattern.
static unsigned getPatternSize(TreePatternNode *P, CodeGenDAGPatterns &CGP) {
assert(P->hasTypeSet() && "Not a valid pattern node to size!");
unsigned Size = 3; // The node itself.
// If the root node is a ConstantSDNode, increases its size.
// e.g. (set R32:$dst, 0).
if (P->isLeaf() && dynamic_cast<IntInit*>(P->getLeafValue()))
Size += 2;
// FIXME: This is a hack to statically increase the priority of patterns
// which maps a sub-dag to a complex pattern. e.g. favors LEA over ADD.
// Later we can allow complexity / cost for each pattern to be (optionally)
// specified. To get best possible pattern match we'll need to dynamically
// calculate the complexity of all patterns a dag can potentially map to.
const ComplexPattern *AM = P->getComplexPatternInfo(CGP);
if (AM)
Size += AM->getNumOperands() * 3;
// If this node has some predicate function that must match, it adds to the
// complexity of this node.
if (!P->getPredicateFns().empty())
++Size;
// Count children in the count if they are also nodes.
for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i) {
TreePatternNode *Child = P->getChild(i);
if (!Child->isLeaf() && Child->getType() != MVT::Other)
Size += getPatternSize(Child, CGP);
else if (Child->isLeaf()) {
if (dynamic_cast<IntInit*>(Child->getLeafValue()))
Size += 5; // Matches a ConstantSDNode (+3) and a specific value (+2).
else if (Child->getComplexPatternInfo(CGP))
Size += getPatternSize(Child, CGP);
else if (!Child->getPredicateFns().empty())
++Size;
}
}
return Size;
}
/// getResultPatternCost - Compute the number of instructions for this pattern.
/// This is a temporary hack. We should really include the instruction
/// latencies in this calculation.
static unsigned getResultPatternCost(TreePatternNode *P,
CodeGenDAGPatterns &CGP) {
if (P->isLeaf()) return 0;
unsigned Cost = 0;
Record *Op = P->getOperator();
if (Op->isSubClassOf("Instruction")) {
Cost++;
CodeGenInstruction &II = CGP.getTargetInfo().getInstruction(Op);
if (II.usesCustomInserter)
Cost += 10;
}
for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i)
Cost += getResultPatternCost(P->getChild(i), CGP);
return Cost;
}
/// getResultPatternCodeSize - Compute the code size of instructions for this
/// pattern.
static unsigned getResultPatternSize(TreePatternNode *P,
CodeGenDAGPatterns &CGP) {
if (P->isLeaf()) return 0;
unsigned Cost = 0;
Record *Op = P->getOperator();
if (Op->isSubClassOf("Instruction")) {
Cost += Op->getValueAsInt("CodeSize");
}
for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i)
Cost += getResultPatternSize(P->getChild(i), CGP);
return Cost;
}
//===----------------------------------------------------------------------===//
// Predicate emitter implementation.
//
void DAGISelEmitter::EmitPredicateFunctions(raw_ostream &OS) {
OS << "\n// Predicate functions.\n";
// Walk the pattern fragments, adding them to a map, which sorts them by
// name.
typedef std::map<std::string, std::pair<Record*, TreePattern*> > PFsByNameTy;
PFsByNameTy PFsByName;
for (CodeGenDAGPatterns::pf_iterator I = CGP.pf_begin(), E = CGP.pf_end();
I != E; ++I)
PFsByName.insert(std::make_pair(I->first->getName(), *I));
for (PFsByNameTy::iterator I = PFsByName.begin(), E = PFsByName.end();
I != E; ++I) {
Record *PatFragRecord = I->second.first;// Record that derives from PatFrag.
TreePattern *P = I->second.second;
// If there is a code init for this fragment, emit the predicate code.
std::string Code = PatFragRecord->getValueAsCode("Predicate");
if (Code.empty()) continue;
if (P->getOnlyTree()->isLeaf())
OS << "inline bool Predicate_" << PatFragRecord->getName()
<< "(SDNode *N) const {\n";
else {
std::string ClassName =
CGP.getSDNodeInfo(P->getOnlyTree()->getOperator()).getSDClassName();
const char *C2 = ClassName == "SDNode" ? "N" : "inN";
OS << "inline bool Predicate_" << PatFragRecord->getName()
<< "(SDNode *" << C2 << ") const {\n";
if (ClassName != "SDNode")
OS << " " << ClassName << " *N = cast<" << ClassName << ">(inN);\n";
}
OS << Code << "\n}\n";
}
OS << "\n\n";
}
namespace {
// PatternSortingPredicate - return true if we prefer to match LHS before RHS.
// In particular, we want to match maximal patterns first and lowest cost within
// a particular complexity first.
struct PatternSortingPredicate {
PatternSortingPredicate(CodeGenDAGPatterns &cgp) : CGP(cgp) {}
CodeGenDAGPatterns &CGP;
bool operator()(const PatternToMatch *LHS,
const PatternToMatch *RHS) {
unsigned LHSSize = getPatternSize(LHS->getSrcPattern(), CGP);
unsigned RHSSize = getPatternSize(RHS->getSrcPattern(), CGP);
LHSSize += LHS->getAddedComplexity();
RHSSize += RHS->getAddedComplexity();
if (LHSSize > RHSSize) return true; // LHS -> bigger -> less cost
if (LHSSize < RHSSize) return false;
// If the patterns have equal complexity, compare generated instruction cost
unsigned LHSCost = getResultPatternCost(LHS->getDstPattern(), CGP);
unsigned RHSCost = getResultPatternCost(RHS->getDstPattern(), CGP);
if (LHSCost < RHSCost) return true;
if (LHSCost > RHSCost) return false;
unsigned LHSPatSize = getResultPatternSize(LHS->getDstPattern(), CGP);
unsigned RHSPatSize = getResultPatternSize(RHS->getDstPattern(), CGP);
if (LHSPatSize < RHSPatSize) return true;
if (LHSPatSize > RHSPatSize) return false;
// Sort based on the UID of the pattern, giving us a deterministic ordering.
assert(LHS == RHS || LHS->ID != RHS->ID);
return LHS->ID < RHS->ID;
}
};
}
void DAGISelEmitter::run(raw_ostream &OS) {
EmitSourceFileHeader("DAG Instruction Selector for the " +
CGP.getTargetInfo().getName() + " target", OS);
OS << "// *** NOTE: This file is #included into the middle of the target\n"
<< "// *** instruction selector class. These functions are really "
<< "methods.\n\n";
DEBUG(errs() << "\n\nALL PATTERNS TO MATCH:\n\n";
for (CodeGenDAGPatterns::ptm_iterator I = CGP.ptm_begin(),
E = CGP.ptm_end(); I != E; ++I) {
errs() << "PATTERN: "; I->getSrcPattern()->dump();
errs() << "\nRESULT: "; I->getDstPattern()->dump();
errs() << "\n";
});
// FIXME: These are being used by hand written code, gross.
EmitPredicateFunctions(OS);
// Add all the patterns to a temporary list so we can sort them.
std::vector<const PatternToMatch*> Patterns;
for (CodeGenDAGPatterns::ptm_iterator I = CGP.ptm_begin(), E = CGP.ptm_end();
I != E; ++I)
Patterns.push_back(&*I);
// We want to process the matches in order of minimal cost. Sort the patterns
// so the least cost one is at the start.
std::stable_sort(Patterns.begin(), Patterns.end(),
PatternSortingPredicate(CGP));
// Convert each variant of each pattern into a Matcher.
std::vector<Matcher*> PatternMatchers;
for (unsigned i = 0, e = Patterns.size(); i != e; ++i) {
for (unsigned Variant = 0; ; ++Variant) {
if (Matcher *M = ConvertPatternToMatcher(*Patterns[i], Variant, CGP))
PatternMatchers.push_back(M);
else
break;
}
}
Matcher *TheMatcher = new ScopeMatcher(&PatternMatchers[0],
PatternMatchers.size());
TheMatcher = OptimizeMatcher(TheMatcher, CGP);
//Matcher->dump();
EmitMatcherTable(TheMatcher, CGP, OS);
delete TheMatcher;
}