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 
15 using namespace llvm;
16 
17 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
18 LLVM_DUMP_METHOD void SubtargetFeatureInfo::dump() const {
19   errs() << getEnumName() << " " << Index << "\n" << *TheDef;
20 }
21 #endif
22 
23 std::vector<std::pair<Record *, SubtargetFeatureInfo>>
24 SubtargetFeatureInfo::getAll(const RecordKeeper &Records) {
25   std::vector<std::pair<Record *, SubtargetFeatureInfo>> SubtargetFeatures;
26   std::vector<Record *> AllPredicates =
27       Records.getAllDerivedDefinitions("Predicate");
28   for (Record *Pred : AllPredicates) {
29     // Ignore predicates that are not intended for the assembler.
30     //
31     // The "AssemblerMatcherPredicate" string should be promoted to an argument
32     // if we re-use the machinery for non-assembler purposes in future.
33     if (!Pred->getValueAsBit("AssemblerMatcherPredicate"))
34       continue;
35 
36     if (Pred->getName().empty())
37       PrintFatalError(Pred->getLoc(), "Predicate has no name!");
38 
39     // Ignore always true predicates.
40     if (Pred->getValueAsString("CondString").empty())
41       continue;
42 
43     SubtargetFeatures.emplace_back(
44         Pred, SubtargetFeatureInfo(Pred, SubtargetFeatures.size()));
45   }
46   return SubtargetFeatures;
47 }
48 
49 void SubtargetFeatureInfo::emitSubtargetFeatureBitEnumeration(
50     const SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS,
51     const std::map<std::string, unsigned> *HwModes) {
52   OS << "// Bits for subtarget features that participate in "
53      << "instruction matching.\n";
54   unsigned Size = SubtargetFeatures.size();
55   if (HwModes)
56     Size += HwModes->size();
57 
58   OS << "enum SubtargetFeatureBits : " << getMinimalTypeForRange(Size)
59      << " {\n";
60   for (const auto &SF : SubtargetFeatures) {
61     const SubtargetFeatureInfo &SFI = SF.second;
62     OS << "  " << SFI.getEnumBitName() << " = " << SFI.Index << ",\n";
63   }
64 
65   if (HwModes) {
66     unsigned Offset = SubtargetFeatures.size();
67     for (const auto &M : *HwModes) {
68       OS << "  Feature_HwMode" << M.second << "Bit = " << (M.second + Offset)
69          << ",\n";
70     }
71   }
72 
73   OS << "};\n\n";
74 }
75 
76 void SubtargetFeatureInfo::emitNameTable(
77     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
78   // Need to sort the name table so that lookup by the log of the enum value
79   // gives the proper name. More specifically, for a feature of value 1<<n,
80   // SubtargetFeatureNames[n] should be the name of the feature.
81   uint64_t IndexUB = 0;
82   for (const auto &SF : SubtargetFeatures)
83     if (IndexUB <= SF.second.Index)
84       IndexUB = SF.second.Index+1;
85 
86   std::vector<std::string> Names;
87   if (IndexUB > 0)
88     Names.resize(IndexUB);
89   for (const auto &SF : SubtargetFeatures)
90     Names[SF.second.Index] = SF.second.getEnumName();
91 
92   OS << "static const char *SubtargetFeatureNames[] = {\n";
93   for (uint64_t I = 0; I < IndexUB; ++I)
94     OS << "  \"" << Names[I] << "\",\n";
95 
96   // A small number of targets have no predicates. Null terminate the array to
97   // avoid a zero-length array.
98   OS << "  nullptr\n"
99      << "};\n\n";
100 }
101 
102 void SubtargetFeatureInfo::emitComputeAvailableFeatures(
103     StringRef TargetName, StringRef ClassName, StringRef FuncName,
104     const SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS,
105     StringRef ExtraParams, const std::map<std::string, unsigned> *HwModes) {
106   OS << "PredicateBitset " << ClassName << "::\n"
107      << FuncName << "(const " << TargetName << "Subtarget *Subtarget";
108   if (!ExtraParams.empty())
109     OS << ", " << ExtraParams;
110   OS << ") const {\n";
111   OS << "  PredicateBitset Features;\n";
112   for (const auto &SF : SubtargetFeatures) {
113     const SubtargetFeatureInfo &SFI = SF.second;
114     StringRef CondStr = SFI.TheDef->getValueAsString("CondString");
115     assert(!CondStr.empty() && "true predicate should have been filtered");
116 
117     OS << "  if (" << CondStr << ")\n";
118     OS << "    Features.set(" << SFI.getEnumBitName() << ");\n";
119   }
120 
121   if (HwModes) {
122     for (const auto &M : *HwModes) {
123       OS << "  if (" << M.first << ")\n";
124       OS << "    Features.set(Feature_HwMode" << M.second << "Bit);\n";
125     }
126   }
127 
128   OS << "  return Features;\n";
129   OS << "}\n\n";
130 }
131 
132 // If ParenIfBinOp is true, print a surrounding () if Val uses && or ||.
133 static bool emitFeaturesAux(StringRef TargetName, const Init &Val,
134                             bool ParenIfBinOp, raw_ostream &OS) {
135   if (auto *D = dyn_cast<DefInit>(&Val)) {
136     if (!D->getDef()->isSubClassOf("SubtargetFeature"))
137       return true;
138     OS << "FB[" << TargetName << "::" << D->getAsString() << "]";
139     return false;
140   }
141   if (auto *D = dyn_cast<DagInit>(&Val)) {
142     auto *Op = dyn_cast<DefInit>(D->getOperator());
143     if (!Op)
144       return true;
145     StringRef OpName = Op->getDef()->getName();
146     if (OpName == "not" && D->getNumArgs() == 1) {
147       OS << '!';
148       return emitFeaturesAux(TargetName, *D->getArg(0), true, OS);
149     }
150     if ((OpName == "any_of" || OpName == "all_of") && D->getNumArgs() > 0) {
151       bool Paren = D->getNumArgs() > 1 && std::exchange(ParenIfBinOp, true);
152       if (Paren)
153         OS << '(';
154       ListSeparator LS(OpName == "any_of" ? " || " : " && ");
155       for (auto *Arg : D->getArgs()) {
156         OS << LS;
157         if (emitFeaturesAux(TargetName, *Arg, ParenIfBinOp, OS))
158           return true;
159       }
160       if (Paren)
161         OS << ')';
162       return false;
163     }
164   }
165   return true;
166 }
167 
168 void SubtargetFeatureInfo::emitComputeAssemblerAvailableFeatures(
169     StringRef TargetName, StringRef ClassName, StringRef FuncName,
170     SubtargetFeatureInfoMap &SubtargetFeatures, raw_ostream &OS) {
171   OS << "FeatureBitset ";
172   if (!ClassName.empty())
173     OS << TargetName << ClassName << "::\n";
174   OS << FuncName << "(const FeatureBitset &FB) ";
175   if (!ClassName.empty())
176     OS << "const ";
177   OS << "{\n";
178   OS << "  FeatureBitset Features;\n";
179   for (const auto &SF : SubtargetFeatures) {
180     const SubtargetFeatureInfo &SFI = SF.second;
181 
182     OS << "  if (";
183     emitFeaturesAux(TargetName, *SFI.TheDef->getValueAsDag("AssemblerCondDag"),
184                     /*ParenIfBinOp=*/false, OS);
185     OS << ")\n";
186     OS << "    Features.set(" << SFI.getEnumBitName() << ");\n";
187   }
188   OS << "  return Features;\n";
189   OS << "}\n\n";
190 }
191