1 //===- SubtargetFeatureInfo.cpp - Helpers for subtarget features ----------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "SubtargetFeatureInfo.h"
10 
11 #include "Types.h"
12 #include "llvm/Config/llvm-config.h"
13 #include "llvm/TableGen/Record.h"
14 
15 #include <map>
16 
17 using namespace llvm;
18 
19 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
20 LLVM_DUMP_METHOD void SubtargetFeatureInfo::dump() const {
21   errs() << getEnumName() << " " << Index << "\n" << *TheDef;
22 }
23 #endif
24 
25 std::vector<std::pair<Record *, SubtargetFeatureInfo>>
26 SubtargetFeatureInfo::getAll(const RecordKeeper &Records) {
27   std::vector<std::pair<Record *, SubtargetFeatureInfo>> SubtargetFeatures;
28   std::vector<Record *> AllPredicates =
29       Records.getAllDerivedDefinitions("Predicate");
30   for (Record *Pred : AllPredicates) {
31     // Ignore predicates that are not intended for the assembler.
32     //
33     // The "AssemblerMatcherPredicate" string should be promoted to an argument
34     // if we re-use the machinery for non-assembler purposes in future.
35     if (!Pred->getValueAsBit("AssemblerMatcherPredicate"))
36       continue;
37 
38     if (Pred->getName().empty())
39       PrintFatalError(Pred->getLoc(), "Predicate has no name!");
40 
41     // Ignore always true predicates.
42     if (Pred->getValueAsString("CondString").empty())
43       continue;
44 
45     SubtargetFeatures.emplace_back(
46         Pred, SubtargetFeatureInfo(Pred, SubtargetFeatures.size()));
47   }
48   return SubtargetFeatures;
49 }
50 
51 void SubtargetFeatureInfo::emitSubtargetFeatureBitEnumeration(
52     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
53   OS << "// Bits for subtarget features that participate in "
54      << "instruction matching.\n";
55   OS << "enum SubtargetFeatureBits : "
56      << getMinimalTypeForRange(SubtargetFeatures.size()) << " {\n";
57   for (const auto &SF : SubtargetFeatures) {
58     const SubtargetFeatureInfo &SFI = SF.second;
59     OS << "  " << SFI.getEnumBitName() << " = " << SFI.Index << ",\n";
60   }
61   OS << "};\n\n";
62 }
63 
64 void SubtargetFeatureInfo::emitNameTable(
65     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
66   // Need to sort the name table so that lookup by the log of the enum value
67   // gives the proper name. More specifically, for a feature of value 1<<n,
68   // SubtargetFeatureNames[n] should be the name of the feature.
69   uint64_t IndexUB = 0;
70   for (const auto &SF : SubtargetFeatures)
71     if (IndexUB <= SF.second.Index)
72       IndexUB = SF.second.Index+1;
73 
74   std::vector<std::string> Names;
75   if (IndexUB > 0)
76     Names.resize(IndexUB);
77   for (const auto &SF : SubtargetFeatures)
78     Names[SF.second.Index] = SF.second.getEnumName();
79 
80   OS << "static const char *SubtargetFeatureNames[] = {\n";
81   for (uint64_t I = 0; I < IndexUB; ++I)
82     OS << "  \"" << Names[I] << "\",\n";
83 
84   // A small number of targets have no predicates. Null terminate the array to
85   // avoid a zero-length array.
86   OS << "  nullptr\n"
87      << "};\n\n";
88 }
89 
90 void SubtargetFeatureInfo::emitComputeAvailableFeatures(
91     StringRef TargetName, StringRef ClassName, StringRef FuncName,
92     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS,
93     StringRef ExtraParams) {
94   OS << "PredicateBitset " << TargetName << ClassName << "::\n"
95      << FuncName << "(const " << TargetName << "Subtarget *Subtarget";
96   if (!ExtraParams.empty())
97     OS << ", " << ExtraParams;
98   OS << ") const {\n";
99   OS << "  PredicateBitset Features;\n";
100   for (const auto &SF : SubtargetFeatures) {
101     const SubtargetFeatureInfo &SFI = SF.second;
102     StringRef CondStr = SFI.TheDef->getValueAsString("CondString");
103     assert(!CondStr.empty() && "true predicate should have been filtered");
104 
105     OS << "  if (" << CondStr << ")\n";
106     OS << "    Features.set(" << SFI.getEnumBitName() << ");\n";
107   }
108   OS << "  return Features;\n";
109   OS << "}\n\n";
110 }
111 
112 void SubtargetFeatureInfo::emitComputeAssemblerAvailableFeatures(
113     StringRef TargetName, StringRef ClassName, StringRef FuncName,
114     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
115   OS << "FeatureBitset " << TargetName << ClassName << "::\n"
116      << FuncName << "(const FeatureBitset& FB) const {\n";
117   OS << "  FeatureBitset Features;\n";
118   for (const auto &SF : SubtargetFeatures) {
119     const SubtargetFeatureInfo &SFI = SF.second;
120 
121     OS << "  if (";
122     std::string CondStorage =
123         SFI.TheDef->getValueAsString("AssemblerCondString");
124     StringRef Conds = CondStorage;
125     std::pair<StringRef, StringRef> Comma = Conds.split(',');
126     bool First = true;
127     do {
128       if (!First)
129         OS << " && ";
130 
131       bool Neg = false;
132       StringRef Cond = Comma.first;
133       if (Cond[0] == '!') {
134         Neg = true;
135         Cond = Cond.substr(1);
136       }
137 
138       OS << "(";
139       if (Neg)
140         OS << "!";
141       OS << "FB[" << TargetName << "::" << Cond << "])";
142 
143       if (Comma.second.empty())
144         break;
145 
146       First = false;
147       Comma = Comma.second.split(',');
148     } while (true);
149 
150     OS << ")\n";
151     OS << "    Features.set(" << SFI.getEnumBitName() << ");\n";
152   }
153   OS << "  return Features;\n";
154   OS << "}\n\n";
155 }
156