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//===- 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
//
/// 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;
}
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) {
const TreePatternNode *LHSSrc = LHS->getSrcPattern();
const TreePatternNode *RHSSrc = RHS->getSrcPattern();
if (LHSSrc->getNumTypes() != 0 && RHSSrc->getNumTypes() != 0 &&
LHSSrc->getType(0) != RHSSrc->getType(0)) {
MVT::SimpleValueType V1 = LHSSrc->getType(0), V2 = RHSSrc->getType(0);
if (MVT(V1).isVector() != MVT(V2).isVector())
return MVT(V2).isVector();
if (MVT(V1).isFloatingPoint() != MVT(V2).isFloatingPoint())
return MVT(V2).isFloatingPoint();
}
// Otherwise, if the patterns might both match, sort based on complexity,
// which means that we prefer to match patterns that cover more nodes in the
// input over nodes that cover fewer.
unsigned LHSSize = LHS->getPatternComplexity(CGP);
unsigned RHSSize = RHS->getPatternComplexity(CGP);
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
// if all other sorting conditions fail.
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";
});
// 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::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());
CodeGenTarget Target(Records);
const std::vector<CodeGenRegister> &Registers = Target.getRegisters();
bool useEmitRegister2 = Registers.size() > 255;
TheMatcher = OptimizeMatcher(TheMatcher, CGP);
//Matcher->dump();
EmitMatcherTable(TheMatcher, CGP, useEmitRegister2, OS);
delete TheMatcher;
}
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