forked from OSchip/llvm-project
195 lines
7.1 KiB
C++
195 lines
7.1 KiB
C++
//===- DAGISelEmitter.cpp - Generate an instruction selector --------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This tablegen backend emits a DAG instruction selector.
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//
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//===----------------------------------------------------------------------===//
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#include "CodeGenDAGPatterns.h"
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#include "DAGISelMatcher.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/TableGen/Record.h"
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#include "llvm/TableGen/TableGenBackend.h"
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using namespace llvm;
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#define DEBUG_TYPE "dag-isel-emitter"
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namespace {
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/// DAGISelEmitter - The top-level class which coordinates construction
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/// and emission of the instruction selector.
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class DAGISelEmitter {
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RecordKeeper &Records; // Just so we can get at the timing functions.
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CodeGenDAGPatterns CGP;
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public:
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explicit DAGISelEmitter(RecordKeeper &R) : Records(R), CGP(R) {}
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void run(raw_ostream &OS);
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};
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} // End anonymous namespace
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//===----------------------------------------------------------------------===//
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// DAGISelEmitter Helper methods
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//
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/// getResultPatternCost - Compute the number of instructions for this pattern.
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/// This is a temporary hack. We should really include the instruction
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/// latencies in this calculation.
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static unsigned getResultPatternCost(TreePatternNode *P,
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CodeGenDAGPatterns &CGP) {
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if (P->isLeaf()) return 0;
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unsigned Cost = 0;
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Record *Op = P->getOperator();
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if (Op->isSubClassOf("Instruction")) {
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Cost++;
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CodeGenInstruction &II = CGP.getTargetInfo().getInstruction(Op);
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if (II.usesCustomInserter)
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Cost += 10;
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}
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for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i)
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Cost += getResultPatternCost(P->getChild(i), CGP);
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return Cost;
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}
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/// getResultPatternCodeSize - Compute the code size of instructions for this
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/// pattern.
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static unsigned getResultPatternSize(TreePatternNode *P,
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CodeGenDAGPatterns &CGP) {
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if (P->isLeaf()) return 0;
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unsigned Cost = 0;
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Record *Op = P->getOperator();
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if (Op->isSubClassOf("Instruction")) {
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Cost += Op->getValueAsInt("CodeSize");
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}
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for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i)
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Cost += getResultPatternSize(P->getChild(i), CGP);
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return Cost;
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}
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namespace {
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// PatternSortingPredicate - return true if we prefer to match LHS before RHS.
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// In particular, we want to match maximal patterns first and lowest cost within
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// a particular complexity first.
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struct PatternSortingPredicate {
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PatternSortingPredicate(CodeGenDAGPatterns &cgp) : CGP(cgp) {}
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CodeGenDAGPatterns &CGP;
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bool operator()(const PatternToMatch *LHS, const PatternToMatch *RHS) {
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const TreePatternNode *LT = LHS->getSrcPattern();
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const TreePatternNode *RT = RHS->getSrcPattern();
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MVT LHSVT = LT->getNumTypes() != 0 ? LT->getSimpleType(0) : MVT::Other;
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MVT RHSVT = RT->getNumTypes() != 0 ? RT->getSimpleType(0) : MVT::Other;
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if (LHSVT.isVector() != RHSVT.isVector())
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return RHSVT.isVector();
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if (LHSVT.isFloatingPoint() != RHSVT.isFloatingPoint())
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return RHSVT.isFloatingPoint();
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// Otherwise, if the patterns might both match, sort based on complexity,
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// which means that we prefer to match patterns that cover more nodes in the
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// input over nodes that cover fewer.
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int LHSSize = LHS->getPatternComplexity(CGP);
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int RHSSize = RHS->getPatternComplexity(CGP);
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if (LHSSize > RHSSize) return true; // LHS -> bigger -> less cost
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if (LHSSize < RHSSize) return false;
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// If the patterns have equal complexity, compare generated instruction cost
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unsigned LHSCost = getResultPatternCost(LHS->getDstPattern(), CGP);
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unsigned RHSCost = getResultPatternCost(RHS->getDstPattern(), CGP);
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if (LHSCost < RHSCost) return true;
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if (LHSCost > RHSCost) return false;
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unsigned LHSPatSize = getResultPatternSize(LHS->getDstPattern(), CGP);
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unsigned RHSPatSize = getResultPatternSize(RHS->getDstPattern(), CGP);
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if (LHSPatSize < RHSPatSize) return true;
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if (LHSPatSize > RHSPatSize) return false;
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// Sort based on the UID of the pattern, to reflect source order.
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// Note that this is not guaranteed to be unique, since a single source
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// pattern may have been resolved into multiple match patterns due to
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// alternative fragments. To ensure deterministic output, always use
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// std::stable_sort with this predicate.
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return LHS->getID() < RHS->getID();
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}
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};
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} // End anonymous namespace
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void DAGISelEmitter::run(raw_ostream &OS) {
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emitSourceFileHeader("DAG Instruction Selector for the " +
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CGP.getTargetInfo().getName().str() + " target", OS);
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OS << "// *** NOTE: This file is #included into the middle of the target\n"
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<< "// *** instruction selector class. These functions are really "
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<< "methods.\n\n";
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OS << "// If GET_DAGISEL_DECL is #defined with any value, only function\n"
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"// declarations will be included when this file is included.\n"
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"// If GET_DAGISEL_BODY is #defined, its value should be the name of\n"
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"// the instruction selector class. Function bodies will be emitted\n"
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"// and each function's name will be qualified with the name of the\n"
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"// class.\n"
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"//\n"
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"// When neither of the GET_DAGISEL* macros is defined, the functions\n"
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"// are emitted inline.\n\n";
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LLVM_DEBUG(errs() << "\n\nALL PATTERNS TO MATCH:\n\n";
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for (CodeGenDAGPatterns::ptm_iterator I = CGP.ptm_begin(),
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E = CGP.ptm_end();
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I != E; ++I) {
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errs() << "PATTERN: ";
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I->getSrcPattern()->dump();
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errs() << "\nRESULT: ";
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I->getDstPattern()->dump();
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errs() << "\n";
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});
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// Add all the patterns to a temporary list so we can sort them.
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Records.startTimer("Sort patterns");
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std::vector<const PatternToMatch*> Patterns;
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for (const PatternToMatch &PTM : CGP.ptms())
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Patterns.push_back(&PTM);
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// We want to process the matches in order of minimal cost. Sort the patterns
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// so the least cost one is at the start.
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llvm::stable_sort(Patterns, PatternSortingPredicate(CGP));
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// Convert each variant of each pattern into a Matcher.
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Records.startTimer("Convert to matchers");
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std::vector<Matcher*> PatternMatchers;
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for (const PatternToMatch *PTM : Patterns) {
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for (unsigned Variant = 0; ; ++Variant) {
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if (Matcher *M = ConvertPatternToMatcher(*PTM, Variant, CGP))
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PatternMatchers.push_back(M);
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else
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break;
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}
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}
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std::unique_ptr<Matcher> TheMatcher =
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std::make_unique<ScopeMatcher>(PatternMatchers);
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Records.startTimer("Optimize matchers");
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OptimizeMatcher(TheMatcher, CGP);
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//Matcher->dump();
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Records.startTimer("Emit matcher table");
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EmitMatcherTable(TheMatcher.get(), CGP, OS);
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}
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namespace llvm {
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void EmitDAGISel(RecordKeeper &RK, raw_ostream &OS) {
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RK.startTimer("Parse patterns");
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DAGISelEmitter(RK).run(OS);
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}
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} // End llvm namespace
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