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     SubtargetFeatures.emplace_back(
42         Pred, SubtargetFeatureInfo(Pred, SubtargetFeatures.size()));
43   }
44   return SubtargetFeatures;
45 }
46 
47 void SubtargetFeatureInfo::emitSubtargetFeatureFlagEnumeration(
48     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
49   OS << "// Flags for subtarget features that participate in "
50      << "instruction matching.\n";
51   OS << "enum SubtargetFeatureFlag : "
52      << getMinimalTypeForEnumBitfield(SubtargetFeatures.size()) << " {\n";
53   for (const auto &SF : SubtargetFeatures) {
54     const SubtargetFeatureInfo &SFI = SF.second;
55     OS << "  " << SFI.getEnumName() << " = (1ULL << " << SFI.Index << "),\n";
56   }
57   OS << "  Feature_None = 0\n";
58   OS << "};\n\n";
59 }
60 
61 void SubtargetFeatureInfo::emitSubtargetFeatureBitEnumeration(
62     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
63   OS << "// Bits for subtarget features that participate in "
64      << "instruction matching.\n";
65   OS << "enum SubtargetFeatureBits : "
66      << getMinimalTypeForRange(SubtargetFeatures.size()) << " {\n";
67   for (const auto &SF : SubtargetFeatures) {
68     const SubtargetFeatureInfo &SFI = SF.second;
69     OS << "  " << SFI.getEnumBitName() << " = " << SFI.Index << ",\n";
70   }
71   OS << "};\n\n";
72 }
73 
74 void SubtargetFeatureInfo::emitNameTable(
75     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
76   // Need to sort the name table so that lookup by the log of the enum value
77   // gives the proper name. More specifically, for a feature of value 1<<n,
78   // SubtargetFeatureNames[n] should be the name of the feature.
79   uint64_t IndexUB = 0;
80   for (const auto &SF : SubtargetFeatures)
81     if (IndexUB <= SF.second.Index)
82       IndexUB = SF.second.Index+1;
83 
84   std::vector<std::string> Names;
85   if (IndexUB > 0)
86     Names.resize(IndexUB);
87   for (const auto &SF : SubtargetFeatures)
88     Names[SF.second.Index] = SF.second.getEnumName();
89 
90   OS << "static const char *SubtargetFeatureNames[] = {\n";
91   for (uint64_t I = 0; I < IndexUB; ++I)
92     OS << "  \"" << Names[I] << "\",\n";
93 
94   // A small number of targets have no predicates. Null terminate the array to
95   // avoid a zero-length array.
96   OS << "  nullptr\n"
97      << "};\n\n";
98 }
99 
100 void SubtargetFeatureInfo::emitComputeAvailableFeatures(
101     StringRef TargetName, StringRef ClassName, StringRef FuncName,
102     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS,
103     StringRef ExtraParams) {
104   OS << "PredicateBitset " << TargetName << ClassName << "::\n"
105      << FuncName << "(const " << TargetName << "Subtarget *Subtarget";
106   if (!ExtraParams.empty())
107     OS << ", " << ExtraParams;
108   OS << ") const {\n";
109   OS << "  PredicateBitset Features;\n";
110   for (const auto &SF : SubtargetFeatures) {
111     const SubtargetFeatureInfo &SFI = SF.second;
112 
113     OS << "  if (" << SFI.TheDef->getValueAsString("CondString") << ")\n";
114     OS << "    Features[" << SFI.getEnumBitName() << "] = 1;\n";
115   }
116   OS << "  return Features;\n";
117   OS << "}\n\n";
118 }
119 
120 void SubtargetFeatureInfo::emitComputeAssemblerAvailableFeatures(
121     StringRef TargetName, StringRef ClassName, StringRef FuncName,
122     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
123   OS << "uint64_t " << TargetName << ClassName << "::\n"
124      << FuncName << "(const FeatureBitset& FB) const {\n";
125   OS << "  uint64_t Features = 0;\n";
126   for (const auto &SF : SubtargetFeatures) {
127     const SubtargetFeatureInfo &SFI = SF.second;
128 
129     OS << "  if (";
130     std::string CondStorage =
131         SFI.TheDef->getValueAsString("AssemblerCondString");
132     StringRef Conds = CondStorage;
133     std::pair<StringRef, StringRef> Comma = Conds.split(',');
134     bool First = true;
135     do {
136       if (!First)
137         OS << " && ";
138 
139       bool Neg = false;
140       StringRef Cond = Comma.first;
141       if (Cond[0] == '!') {
142         Neg = true;
143         Cond = Cond.substr(1);
144       }
145 
146       OS << "(";
147       if (Neg)
148         OS << "!";
149       OS << "FB[" << TargetName << "::" << Cond << "])";
150 
151       if (Comma.second.empty())
152         break;
153 
154       First = false;
155       Comma = Comma.second.split(',');
156     } while (true);
157 
158     OS << ")\n";
159     OS << "    Features |= " << SFI.getEnumName() << ";\n";
160   }
161   OS << "  return Features;\n";
162   OS << "}\n\n";
163 }
164