1 //===- DAGISelEmitter.cpp - Generate an instruction selector --------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This tablegen backend emits a DAG instruction selector.
12 //===----------------------------------------------------------------------===//
14 #include "CodeGenDAGPatterns.h"
15 #include "DAGISelMatcher.h"
16 #include "llvm/Support/Debug.h"
17 #include "llvm/TableGen/Record.h"
18 #include "llvm/TableGen/TableGenBackend.h"
22 /// DAGISelEmitter - The top-level class which coordinates construction
23 /// and emission of the instruction selector.
24 class DAGISelEmitter {
25 CodeGenDAGPatterns CGP;
27 explicit DAGISelEmitter(RecordKeeper &R) : CGP(R) {}
28 void run(raw_ostream &OS);
30 } // End anonymous namespace
32 //===----------------------------------------------------------------------===//
33 // DAGISelEmitter Helper methods
36 /// getResultPatternCost - Compute the number of instructions for this pattern.
37 /// This is a temporary hack. We should really include the instruction
38 /// latencies in this calculation.
39 static unsigned getResultPatternCost(TreePatternNode *P,
40 CodeGenDAGPatterns &CGP) {
41 if (P->isLeaf()) return 0;
44 Record *Op = P->getOperator();
45 if (Op->isSubClassOf("Instruction")) {
47 CodeGenInstruction &II = CGP.getTargetInfo().getInstruction(Op);
48 if (II.usesCustomInserter)
51 for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i)
52 Cost += getResultPatternCost(P->getChild(i), CGP);
56 /// getResultPatternCodeSize - Compute the code size of instructions for this
58 static unsigned getResultPatternSize(TreePatternNode *P,
59 CodeGenDAGPatterns &CGP) {
60 if (P->isLeaf()) return 0;
63 Record *Op = P->getOperator();
64 if (Op->isSubClassOf("Instruction")) {
65 Cost += Op->getValueAsInt("CodeSize");
67 for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i)
68 Cost += getResultPatternSize(P->getChild(i), CGP);
73 // PatternSortingPredicate - return true if we prefer to match LHS before RHS.
74 // In particular, we want to match maximal patterns first and lowest cost within
75 // a particular complexity first.
76 struct PatternSortingPredicate {
77 PatternSortingPredicate(CodeGenDAGPatterns &cgp) : CGP(cgp) {}
78 CodeGenDAGPatterns &CGP;
80 bool operator()(const PatternToMatch *LHS, const PatternToMatch *RHS) {
81 const TreePatternNode *LHSSrc = LHS->getSrcPattern();
82 const TreePatternNode *RHSSrc = RHS->getSrcPattern();
84 MVT LHSVT = (LHSSrc->getNumTypes() != 0 ? LHSSrc->getType(0) : MVT::Other);
85 MVT RHSVT = (RHSSrc->getNumTypes() != 0 ? RHSSrc->getType(0) : MVT::Other);
86 if (LHSVT.isVector() != RHSVT.isVector())
87 return RHSVT.isVector();
89 if (LHSVT.isFloatingPoint() != RHSVT.isFloatingPoint())
90 return RHSVT.isFloatingPoint();
92 // Otherwise, if the patterns might both match, sort based on complexity,
93 // which means that we prefer to match patterns that cover more nodes in the
94 // input over nodes that cover fewer.
95 unsigned LHSSize = LHS->getPatternComplexity(CGP);
96 unsigned RHSSize = RHS->getPatternComplexity(CGP);
97 if (LHSSize > RHSSize) return true; // LHS -> bigger -> less cost
98 if (LHSSize < RHSSize) return false;
100 // If the patterns have equal complexity, compare generated instruction cost
101 unsigned LHSCost = getResultPatternCost(LHS->getDstPattern(), CGP);
102 unsigned RHSCost = getResultPatternCost(RHS->getDstPattern(), CGP);
103 if (LHSCost < RHSCost) return true;
104 if (LHSCost > RHSCost) return false;
106 unsigned LHSPatSize = getResultPatternSize(LHS->getDstPattern(), CGP);
107 unsigned RHSPatSize = getResultPatternSize(RHS->getDstPattern(), CGP);
108 if (LHSPatSize < RHSPatSize) return true;
109 if (LHSPatSize > RHSPatSize) return false;
111 // Sort based on the UID of the pattern, giving us a deterministic ordering
112 // if all other sorting conditions fail.
113 assert(LHS == RHS || LHS->ID != RHS->ID);
114 return LHS->ID < RHS->ID;
117 } // End anonymous namespace
120 void DAGISelEmitter::run(raw_ostream &OS) {
121 emitSourceFileHeader("DAG Instruction Selector for the " +
122 CGP.getTargetInfo().getName() + " target", OS);
124 OS << "// *** NOTE: This file is #included into the middle of the target\n"
125 << "// *** instruction selector class. These functions are really "
128 DEBUG(errs() << "\n\nALL PATTERNS TO MATCH:\n\n";
129 for (CodeGenDAGPatterns::ptm_iterator I = CGP.ptm_begin(),
130 E = CGP.ptm_end(); I != E; ++I) {
131 errs() << "PATTERN: "; I->getSrcPattern()->dump();
132 errs() << "\nRESULT: "; I->getDstPattern()->dump();
136 // Add all the patterns to a temporary list so we can sort them.
137 std::vector<const PatternToMatch*> Patterns;
138 for (CodeGenDAGPatterns::ptm_iterator I = CGP.ptm_begin(), E = CGP.ptm_end();
140 Patterns.push_back(&*I);
142 // We want to process the matches in order of minimal cost. Sort the patterns
143 // so the least cost one is at the start.
144 std::sort(Patterns.begin(), Patterns.end(), PatternSortingPredicate(CGP));
147 // Convert each variant of each pattern into a Matcher.
148 std::vector<Matcher*> PatternMatchers;
149 for (unsigned i = 0, e = Patterns.size(); i != e; ++i) {
150 for (unsigned Variant = 0; ; ++Variant) {
151 if (Matcher *M = ConvertPatternToMatcher(*Patterns[i], Variant, CGP))
152 PatternMatchers.push_back(M);
158 Matcher *TheMatcher = new ScopeMatcher(PatternMatchers);
160 TheMatcher = OptimizeMatcher(TheMatcher, CGP);
162 EmitMatcherTable(TheMatcher, CGP, OS);
168 void EmitDAGISel(RecordKeeper &RK, raw_ostream &OS) {
169 DAGISelEmitter(RK).run(OS);
172 } // End llvm namespace