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 // If ParenIfBinOp is true, print a surrounding () if Val uses && or ||.
112 static bool emitFeaturesAux(StringRef TargetName, const Init &Val,
113                             bool ParenIfBinOp, raw_ostream &OS) {
114   if (auto *D = dyn_cast<DefInit>(&Val)) {
115     if (!D->getDef()->isSubClassOf("SubtargetFeature"))
116       return true;
117     OS << "FB[" << TargetName << "::" << D->getAsString() << "]";
118     return false;
119   }
120   if (auto *D = dyn_cast<DagInit>(&Val)) {
121     std::string Op = D->getOperator()->getAsString();
122     if (Op == "not" && D->getNumArgs() == 1) {
123       OS << '!';
124       return emitFeaturesAux(TargetName, *D->getArg(0), true, OS);
125     }
126     if ((Op == "any_of" || Op == "all_of") && D->getNumArgs() > 0) {
127       bool Paren = D->getNumArgs() > 1 && std::exchange(ParenIfBinOp, true);
128       if (Paren)
129         OS << '(';
130       ListSeparator LS(Op == "any_of" ? " || " : " && ");
131       for (auto *Arg : D->getArgs()) {
132         OS << LS;
133         if (emitFeaturesAux(TargetName, *Arg, ParenIfBinOp, OS))
134           return true;
135       }
136       if (Paren)
137         OS << ')';
138       return false;
139     }
140   }
141   return true;
142 }
143 
144 void SubtargetFeatureInfo::emitComputeAssemblerAvailableFeatures(
145     StringRef TargetName, StringRef ClassName, StringRef FuncName,
146     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
147   OS << "FeatureBitset ";
148   if (!ClassName.empty())
149     OS << TargetName << ClassName << "::\n";
150   OS << FuncName << "(const FeatureBitset &FB) ";
151   if (!ClassName.empty())
152     OS << "const ";
153   OS << "{\n";
154   OS << "  FeatureBitset Features;\n";
155   for (const auto &SF : SubtargetFeatures) {
156     const SubtargetFeatureInfo &SFI = SF.second;
157 
158     OS << "  if (";
159     emitFeaturesAux(TargetName, *SFI.TheDef->getValueAsDag("AssemblerCondDag"),
160                     /*ParenIfBinOp=*/false, OS);
161     OS << ")\n";
162     OS << "    Features.set(" << SFI.getEnumBitName() << ");\n";
163   }
164   OS << "  return Features;\n";
165   OS << "}\n\n";
166 }
167