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 #include "Types.h"
11 #include "llvm/Config/llvm-config.h"
12 #include "llvm/TableGen/Error.h"
13 #include "llvm/TableGen/Record.h"
14 #include <map>
15 
16 using namespace llvm;
17 
18 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
19 LLVM_DUMP_METHOD void SubtargetFeatureInfo::dump() const {
20   errs() << getEnumName() << " " << Index << "\n" << *TheDef;
21 }
22 #endif
23 
24 std::vector<std::pair<Record *, SubtargetFeatureInfo>>
25 SubtargetFeatureInfo::getAll(const RecordKeeper &Records) {
26   std::vector<std::pair<Record *, SubtargetFeatureInfo>> SubtargetFeatures;
27   std::vector<Record *> AllPredicates =
28       Records.getAllDerivedDefinitions("Predicate");
29   for (Record *Pred : AllPredicates) {
30     // Ignore predicates that are not intended for the assembler.
31     //
32     // The "AssemblerMatcherPredicate" string should be promoted to an argument
33     // if we re-use the machinery for non-assembler purposes in future.
34     if (!Pred->getValueAsBit("AssemblerMatcherPredicate"))
35       continue;
36 
37     if (Pred->getName().empty())
38       PrintFatalError(Pred->getLoc(), "Predicate has no name!");
39 
40     // Ignore always true predicates.
41     if (Pred->getValueAsString("CondString").empty())
42       continue;
43 
44     SubtargetFeatures.emplace_back(
45         Pred, SubtargetFeatureInfo(Pred, SubtargetFeatures.size()));
46   }
47   return SubtargetFeatures;
48 }
49 
50 void SubtargetFeatureInfo::emitSubtargetFeatureBitEnumeration(
51     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
52   OS << "// Bits for subtarget features that participate in "
53      << "instruction matching.\n";
54   OS << "enum SubtargetFeatureBits : "
55      << getMinimalTypeForRange(SubtargetFeatures.size()) << " {\n";
56   for (const auto &SF : SubtargetFeatures) {
57     const SubtargetFeatureInfo &SFI = SF.second;
58     OS << "  " << SFI.getEnumBitName() << " = " << SFI.Index << ",\n";
59   }
60   OS << "};\n\n";
61 }
62 
63 void SubtargetFeatureInfo::emitNameTable(
64     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
65   // Need to sort the name table so that lookup by the log of the enum value
66   // gives the proper name. More specifically, for a feature of value 1<<n,
67   // SubtargetFeatureNames[n] should be the name of the feature.
68   uint64_t IndexUB = 0;
69   for (const auto &SF : SubtargetFeatures)
70     if (IndexUB <= SF.second.Index)
71       IndexUB = SF.second.Index+1;
72 
73   std::vector<std::string> Names;
74   if (IndexUB > 0)
75     Names.resize(IndexUB);
76   for (const auto &SF : SubtargetFeatures)
77     Names[SF.second.Index] = SF.second.getEnumName();
78 
79   OS << "static const char *SubtargetFeatureNames[] = {\n";
80   for (uint64_t I = 0; I < IndexUB; ++I)
81     OS << "  \"" << Names[I] << "\",\n";
82 
83   // A small number of targets have no predicates. Null terminate the array to
84   // avoid a zero-length array.
85   OS << "  nullptr\n"
86      << "};\n\n";
87 }
88 
89 void SubtargetFeatureInfo::emitComputeAvailableFeatures(
90     StringRef TargetName, StringRef ClassName, StringRef FuncName,
91     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS,
92     StringRef ExtraParams) {
93   OS << "PredicateBitset " << TargetName << ClassName << "::\n"
94      << FuncName << "(const " << TargetName << "Subtarget *Subtarget";
95   if (!ExtraParams.empty())
96     OS << ", " << ExtraParams;
97   OS << ") const {\n";
98   OS << "  PredicateBitset Features;\n";
99   for (const auto &SF : SubtargetFeatures) {
100     const SubtargetFeatureInfo &SFI = SF.second;
101     StringRef CondStr = SFI.TheDef->getValueAsString("CondString");
102     assert(!CondStr.empty() && "true predicate should have been filtered");
103 
104     OS << "  if (" << CondStr << ")\n";
105     OS << "    Features.set(" << SFI.getEnumBitName() << ");\n";
106   }
107   OS << "  return Features;\n";
108   OS << "}\n\n";
109 }
110 
111 void SubtargetFeatureInfo::emitComputeAssemblerAvailableFeatures(
112     StringRef TargetName, StringRef ClassName, StringRef FuncName,
113     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
114   OS << "FeatureBitset " << TargetName << ClassName << "::\n"
115      << FuncName << "(const FeatureBitset &FB) const {\n";
116   OS << "  FeatureBitset Features;\n";
117   for (const auto &SF : SubtargetFeatures) {
118     const SubtargetFeatureInfo &SFI = SF.second;
119 
120     OS << "  if (";
121 
122     const DagInit *D = SFI.TheDef->getValueAsDag("AssemblerCondDag");
123     std::string CombineType = D->getOperator()->getAsString();
124     if (CombineType != "any_of" && CombineType != "all_of")
125       PrintFatalError(SFI.TheDef->getLoc(), "Invalid AssemblerCondDag!");
126     if (D->getNumArgs() == 0)
127       PrintFatalError(SFI.TheDef->getLoc(), "Invalid AssemblerCondDag!");
128     bool IsOr = CombineType == "any_of";
129 
130     if (IsOr)
131       OS << "(";
132 
133     ListSeparator LS(IsOr ? " || " : " && ");
134     for (auto *Arg : D->getArgs()) {
135       OS << LS;
136       if (auto *NotArg = dyn_cast<DagInit>(Arg)) {
137         if (NotArg->getOperator()->getAsString() != "not" ||
138             NotArg->getNumArgs() != 1)
139           PrintFatalError(SFI.TheDef->getLoc(), "Invalid AssemblerCondDag!");
140         Arg = NotArg->getArg(0);
141         OS << "!";
142       }
143       if (!isa<DefInit>(Arg) ||
144           !cast<DefInit>(Arg)->getDef()->isSubClassOf("SubtargetFeature"))
145         PrintFatalError(SFI.TheDef->getLoc(), "Invalid AssemblerCondDag!");
146       OS << "FB[" << TargetName << "::" << Arg->getAsString() << "]";
147     }
148 
149     if (IsOr)
150       OS << ")";
151 
152     OS << ")\n";
153     OS << "    Features.set(" << SFI.getEnumBitName() << ");\n";
154   }
155   OS << "  return Features;\n";
156   OS << "}\n\n";
157 }
158