Use std::bitset for SubtargetFeatures.

Previously, subtarget features were a bitfield with the underlying type being uint64_t. 
Since several targets (X86 and ARM, in particular) have hit or were very close to hitting this bound, switching the features to use a bitset.
No functional change.

The first several times this was committed (e.g. r229831, r233055), it caused several buildbot failures.
Apparently the reason for most failures was both clang and gcc's inability to deal with large numbers (> 10K) of bitset constructor calls in tablegen-generated initializers of instruction info tables. 
This should now be fixed.

llvm-svn: 238192

1 files changed, 27 insertions, 30 deletions

diff --git a/llvm/utils/TableGen/SubtargetEmitter.cpp b/llvm/utils/TableGen/SubtargetEmitter.cpp
index 5ab7b13..de9c7a6 100644
--- a/llvm/utils/TableGen/SubtargetEmitter.cpp
+++ b/llvm/utils/TableGen/SubtargetEmitter.cpp
@@ -16,6 +16,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/MC/MCInstrItineraries.h"
+#include "llvm/MC/SubtargetFeature.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Format.h"
 #include "llvm/TableGen/Error.h"
@@ -62,7 +63,7 @@ class SubtargetEmitter {
   CodeGenSchedModels &SchedModels;
   std::string Target;
 
-  void Enumeration(raw_ostream &OS, const char *ClassName, bool isBits);
+  void Enumeration(raw_ostream &OS, const char *ClassName);
   unsigned FeatureKeyValues(raw_ostream &OS);
   unsigned CPUKeyValues(raw_ostream &OS);
   void FormItineraryStageString(const std::string &Names,
@@ -112,8 +113,7 @@ public:
 // Enumeration - Emit the specified class as an enumeration.
 //
 void SubtargetEmitter::Enumeration(raw_ostream &OS,
-                                   const char *ClassName,
-                                   bool isBits) {
+                                   const char *ClassName) {
   // Get all records of class and sort
   std::vector<Record*> DefList = Records.getAllDerivedDefinitions(ClassName);
   std::sort(DefList.begin(), DefList.end(), LessRecord());
@@ -121,8 +121,8 @@ void SubtargetEmitter::Enumeration(raw_ostream &OS,
   unsigned N = DefList.size();
   if (N == 0)
     return;
-  if (N > 64)
-    PrintFatalError("Too many (> 64) subtarget features!");
+  if (N > MAX_SUBTARGET_FEATURES)
+    PrintFatalError("Too many subtarget features! Bump MAX_SUBTARGET_FEATURES.");
 
   OS << "namespace " << Target << " {\n";
 
@@ -135,21 +135,14 @@ void SubtargetEmitter::Enumeration(raw_ostream &OS,
     Record *Def = DefList[i];
 
     // Get and emit name
-    OS << "  " << Def->getName();
-
-    // If bit flags then emit expression (1 << i)
-    if (isBits)  OS << " = " << " 1ULL << " << i;
-
-    // Depending on 'if more in the list' emit comma
+    OS << "  " << Def->getName() << " = " << i;
     if (++i < N) OS << ",";
 
     OS << "\n";
   }
 
-  // Close enumeration
-  OS << "};\n";
-
-  OS << "}\n";
+  // Close enumeration and namespace
+  OS << "};\n}\n";
 }
 
 //
@@ -183,22 +176,24 @@ unsigned SubtargetEmitter::FeatureKeyValues(raw_ostream &OS) {
 
     if (CommandLineName.empty()) continue;
 
-    // Emit as { "feature", "description", featureEnum, i1 | i2 | ... | in }
+    // Emit as { "feature", "description", { featureEnum }, { i1 , i2 , ... , in } }
     OS << "  { "
        << "\"" << CommandLineName << "\", "
        << "\"" << Desc << "\", "
-       << Target << "::" << Name << ", ";
+       << "{ " << Target << "::" << Name << " }, ";
 
     const std::vector<Record*> &ImpliesList =
       Feature->getValueAsListOfDefs("Implies");
 
     if (ImpliesList.empty()) {
-      OS << "0ULL";
+      OS << "{ }";
     } else {
+      OS << "{ ";
       for (unsigned j = 0, M = ImpliesList.size(); j < M;) {
         OS << Target << "::" << ImpliesList[j]->getName();
-        if (++j < M) OS << " | ";
+        if (++j < M) OS << ", ";
       }
+      OS << " }";
     }
 
     OS << " }";
@@ -240,22 +235,24 @@ unsigned SubtargetEmitter::CPUKeyValues(raw_ostream &OS) {
     const std::vector<Record*> &FeatureList =
       Processor->getValueAsListOfDefs("Features");
 
-    // Emit as { "cpu", "description", f1 | f2 | ... fn },
+    // Emit as { "cpu", "description", { f1 , f2 , ... fn } },
     OS << "  { "
        << "\"" << Name << "\", "
        << "\"Select the " << Name << " processor\", ";
 
     if (FeatureList.empty()) {
-      OS << "0ULL";
+      OS << "{ }";
     } else {
+      OS << "{ ";
       for (unsigned j = 0, M = FeatureList.size(); j < M;) {
         OS << Target << "::" << FeatureList[j]->getName();
-        if (++j < M) OS << " | ";
+        if (++j < M) OS << ", ";
       }
+      OS << " }";
     }
 
-    // The "0" is for the "implies" section of this data structure.
-    OS << ", 0ULL }";
+    // The { } is for the "implies" section of this data structure.
+    OS << ", { } }";
 
     // Depending on 'if more in the list' emit comma
     if (++i < N) OS << ",";
@@ -1383,7 +1380,7 @@ void SubtargetEmitter::ParseFeaturesFunction(raw_ostream &OS,
   }
 
   OS << "  InitMCProcessorInfo(CPU, FS);\n"
-     << "  uint64_t Bits = getFeatureBits();\n";
+     << "  const FeatureBitset& Bits = getFeatureBits();\n";
 
   for (unsigned i = 0; i < Features.size(); i++) {
     // Next record
@@ -1393,12 +1390,12 @@ void SubtargetEmitter::ParseFeaturesFunction(raw_ostream &OS,
     const std::string &Attribute = R->getValueAsString("Attribute");
 
     if (Value=="true" || Value=="false")
-      OS << "  if ((Bits & " << Target << "::"
-         << Instance << ") != 0) "
+      OS << "  if (Bits[" << Target << "::"
+         << Instance << "]) "
          << Attribute << " = " << Value << ";\n";
     else
-      OS << "  if ((Bits & " << Target << "::"
-         << Instance << ") != 0 && "
+      OS << "  if (Bits[" << Target << "::"
+         << Instance << "] && "
          << Attribute << " < " << Value << ") "
          << Attribute << " = " << Value << ";\n";
   }
@@ -1416,7 +1413,7 @@ void SubtargetEmitter::run(raw_ostream &OS) {
   OS << "#undef GET_SUBTARGETINFO_ENUM\n";
 
   OS << "namespace llvm {\n";
-  Enumeration(OS, "SubtargetFeature", true);
+  Enumeration(OS, "SubtargetFeature");
   OS << "} // End llvm namespace \n";
   OS << "#endif // GET_SUBTARGETINFO_ENUM\n\n";