Add an "implies" field to features. This indicates that, if the current

feature is set, then the features in the implied list should be set also.
The opposite is also enforced: if a feature in the implied list isn't set,
then the feature that owns that implies list shouldn't be set either.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36756 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 132 insertions, 66 deletions

diff --git a/include/llvm/Target/SubtargetFeature.h b/include/llvm/Target/SubtargetFeature.h
index f6a83dfbdb..e809fc0a2c 100644
--- a/include/llvm/Target/SubtargetFeature.h
+++ b/include/llvm/Target/SubtargetFeature.h
@@ -34,6 +34,7 @@ struct SubtargetFeatureKV {
   const char *Key;                      // K-V key string
   const char *Desc;                     // Help descriptor
   uint32_t Value;                       // K-V integer value
+  uint32_t Implies;                     // K-V bit mask
   
   // Compare routine for std binary search
   bool operator<(const SubtargetFeatureKV &S) const {
diff --git a/lib/Target/SubtargetFeature.cpp b/lib/Target/SubtargetFeature.cpp
index 4669e0fdc3..598f02982b 100644
--- a/lib/Target/SubtargetFeature.cpp
+++ b/lib/Target/SubtargetFeature.cpp
@@ -199,6 +199,43 @@ void SubtargetFeatures::setCPUIfNone(const std::string &String) {
   if (Features[0].empty()) setCPU(String);
 }
 
+/// SetImpliedBits - For each feature that is (transitively) implied by this
+/// feature, set it.
+/// 
+static
+void SetImpliedBits(uint32_t &Bits, const SubtargetFeatureKV *FeatureEntry,
+                    const SubtargetFeatureKV *FeatureTable,
+                    size_t FeatureTableSize) {
+  for (size_t i = 0; i < FeatureTableSize; ++i) {
+    const SubtargetFeatureKV &FE = FeatureTable[i];
+
+    if (FeatureEntry->Value == FE.Value) continue;
+
+    if (FeatureEntry->Implies & FE.Value) {
+      Bits |= FE.Value;
+      SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
+    }
+  }
+}
+
+/// ClearImpliedBits - For each feature that (transitively) implies this
+/// feature, clear it.
+/// 
+static
+void ClearImpliedBits(uint32_t &Bits, const SubtargetFeatureKV *FeatureEntry,
+                      const SubtargetFeatureKV *FeatureTable,
+                      size_t FeatureTableSize) {
+  for (size_t i = 0; i < FeatureTableSize; ++i) {
+    const SubtargetFeatureKV &FE = FeatureTable[i];
+
+    if (FeatureEntry->Value == FE.Value) continue;
+
+    if (FE.Implies & FeatureEntry->Value) {
+      Bits &= ~FE.Value;
+      ClearImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
+    }
+  }
+}
 
 /// getBits - Get feature bits.
 ///
@@ -251,8 +288,17 @@ uint32_t SubtargetFeatures::getBits(const SubtargetFeatureKV *CPUTable,
     // If there is a match
     if (FeatureEntry) {
       // Enable/disable feature in bits
-      if (isEnabled(Feature)) Bits |=  FeatureEntry->Value;
-      else                    Bits &= ~FeatureEntry->Value;
+      if (isEnabled(Feature)) {
+        Bits |=  FeatureEntry->Value;
+
+        // For each feature that this implies, set it.
+        SetImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
+      } else {
+        Bits &= ~FeatureEntry->Value;
+
+        // For each feature that implies this, clear it.
+        ClearImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
+      }
     } else {
       cerr << "'" << Feature
            << "' is not a recognized feature for this target"
@@ -260,6 +306,7 @@ uint32_t SubtargetFeatures::getBits(const SubtargetFeatureKV *CPUTable,
            << "\n";
     }
   }
+
   return Bits;
 }
 
diff --git a/lib/Target/Target.td b/lib/Target/Target.td
index 938e4cdc8f..f98c414d34 100644
--- a/lib/Target/Target.td
+++ b/lib/Target/Target.td
@@ -338,7 +338,8 @@ class Target {
 //===----------------------------------------------------------------------===//
 // SubtargetFeature - A characteristic of the chip set.
 //
-class SubtargetFeature<string n, string a,  string v, string d> {
+class SubtargetFeature<string n, string a,  string v, string d,
+                       list<SubtargetFeature> i = []> {
   // Name - Feature name.  Used by command line (-mattr=) to determine the
   // appropriate target chip.
   //
@@ -356,6 +357,11 @@ class SubtargetFeature<string n, string a,  string v, string d> {
   // information.
   //
   string Desc = d;
+
+  // Implies - Features that this feature implies are present. If one of those
+  // features isn't set, then this one shouldn't be set either.
+  //
+  list<SubtargetFeature> Implies = i;
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/lib/Target/X86/X86.td b/lib/Target/X86/X86.td
index 94e69f5a36..89cb749d64 100644
--- a/lib/Target/X86/X86.td
+++ b/lib/Target/X86/X86.td
@@ -18,24 +18,28 @@ include "../Target.td"
 
 //===----------------------------------------------------------------------===//
 // X86 Subtarget features.
-//
+//===----------------------------------------------------------------------===//
  
-def Feature64Bit     : SubtargetFeature<"64bit", "HasX86_64", "true",
-                                        "Support 64-bit instructions">;
-def FeatureMMX       : SubtargetFeature<"mmx","X86SSELevel", "MMX",
-                                        "Enable MMX instructions">;
-def FeatureSSE1      : SubtargetFeature<"sse", "X86SSELevel", "SSE1",
-                                        "Enable SSE instructions">;
-def FeatureSSE2      : SubtargetFeature<"sse2", "X86SSELevel", "SSE2",
-                                        "Enable SSE2 instructions">;
-def FeatureSSE3      : SubtargetFeature<"sse3", "X86SSELevel", "SSE3",
-                                        "Enable SSE3 instructions">;
-def FeatureSSSE3     : SubtargetFeature<"ssse3", "X86SSELevel", "SSSE3",
-                                        "Enable SSSE3 instructions">;
-def Feature3DNow     : SubtargetFeature<"3dnow", "X863DNowLevel", "ThreeDNow",
-                                        "Enable 3DNow! instructions">;
-def Feature3DNowA    : SubtargetFeature<"3dnowa", "X863DNowLevel", "ThreeDNowA",
-                                        "Enable 3DNow! Athlon instructions">;
+def Feature64Bit   : SubtargetFeature<"64bit", "HasX86_64", "true",
+                                      "Support 64-bit instructions">;
+def FeatureMMX     : SubtargetFeature<"mmx","X86SSELevel", "MMX",
+                                      "Enable MMX instructions">;
+def FeatureSSE1    : SubtargetFeature<"sse", "X86SSELevel", "SSE1",
+                                      "Enable SSE instructions",
+                                      [FeatureMMX]>;
+def FeatureSSE2    : SubtargetFeature<"sse2", "X86SSELevel", "SSE2",
+                                      "Enable SSE2 instructions",
+                                      [FeatureSSE1]>;
+def FeatureSSE3    : SubtargetFeature<"sse3", "X86SSELevel", "SSE3",
+                                      "Enable SSE3 instructions",
+                                      [FeatureSSE2]>;
+def FeatureSSSE3   : SubtargetFeature<"ssse3", "X86SSELevel", "SSSE3",
+                                      "Enable SSSE3 instructions",
+                                      [FeatureSSE3]>;
+def Feature3DNow   : SubtargetFeature<"3dnow", "X863DNowLevel", "ThreeDNow",
+                                      "Enable 3DNow! instructions">;
+def Feature3DNowA  : SubtargetFeature<"3dnowa", "X863DNowLevel", "ThreeDNowA",
+                                      "Enable 3DNow! Athlon instructions">;
 
 //===----------------------------------------------------------------------===//
 // X86 processors supported.
diff --git a/utils/TableGen/SubtargetEmitter.cpp b/utils/TableGen/SubtargetEmitter.cpp
index f6c7a44f34..fc913e69e1 100644
--- a/utils/TableGen/SubtargetEmitter.cpp
+++ b/utils/TableGen/SubtargetEmitter.cpp
@@ -56,8 +56,7 @@ void SubtargetEmitter::Enumeration(std::ostream &OS,
     Record *Def = DefList[i];
     
     // Get and emit name
-    std::string Name = Def->getName();
-    OS << "  " << Name;
+    OS << "  " << Def->getName();
     
     // If bit flags then emit expression (1 << i)
     if (isBits)  OS << " = " << " 1 << " << i;
@@ -73,8 +72,8 @@ void SubtargetEmitter::Enumeration(std::ostream &OS,
 }
 
 //
-// FeatureKeyValues - Emit data of all the subtarget features.  Used by command
-// line.
+// FeatureKeyValues - Emit data of all the subtarget features.  Used by the
+// command line.
 //
 void SubtargetEmitter::FeatureKeyValues(std::ostream &OS) {
   // Gather and sort all the features
@@ -91,18 +90,31 @@ void SubtargetEmitter::FeatureKeyValues(std::ostream &OS) {
     // Next feature
     Record *Feature = FeatureList[i];
 
-    std::string Name = Feature->getName();
-    std::string CommandLineName = Feature->getValueAsString("Name");
-    std::string Desc = Feature->getValueAsString("Desc");
+    const std::string &Name = Feature->getName();
+    const std::string &CommandLineName = Feature->getValueAsString("Name");
+    const std::string &Desc = Feature->getValueAsString("Desc");
     
     if (CommandLineName.empty()) continue;
     
-    // Emit as { "feature", "decription", feactureEnum }
+    // Emit as { "feature", "decription", feactureEnum, i1 | i2 | ... | in }
     OS << "  { "
        << "\"" << CommandLineName << "\", "
        << "\"" << Desc << "\", "
-       << Name
-       << " }";
+       << Name << ", ";
+
+    const std::vector<Record*> &ImpliesList = 
+      Feature->getValueAsListOfDefs("Implies");
+    
+    if (ImpliesList.empty()) {
+      OS << "0";
+    } else {
+      for (unsigned j = 0, M = ImpliesList.size(); j < M;) {
+        OS << ImpliesList[j]->getName();
+        if (++j < M) OS << " | ";
+      }
+    }
+
+    OS << " }";
     
     // Depending on 'if more in the list' emit comma
     if ((i + 1) < N) OS << ",";
@@ -138,8 +150,8 @@ void SubtargetEmitter::CPUKeyValues(std::ostream &OS) {
     // Next processor
     Record *Processor = ProcessorList[i];
 
-    std::string Name = Processor->getValueAsString("Name");
-    std::vector<Record*> FeatureList = 
+    const std::string &Name = Processor->getValueAsString("Name");
+    const std::vector<Record*> &FeatureList = 
       Processor->getValueAsListOfDefs("Features");
     
     // Emit as { "cpu", "description", f1 | f2 | ... fn },
@@ -151,14 +163,13 @@ void SubtargetEmitter::CPUKeyValues(std::ostream &OS) {
       OS << "0";
     } else {
       for (unsigned j = 0, M = FeatureList.size(); j < M;) {
-        Record *Feature = FeatureList[j];
-        std::string Name = Feature->getName();
-        OS << Name;
+        OS << FeatureList[j]->getName();
         if (++j < M) OS << " | ";
       }
     }
     
-    OS << " }";
+    // The "0" is for the "implies" section of this data structure.
+    OS << ", 0 }";
     
     // Depending on 'if more in the list' emit comma
     if (++i < N) OS << ",";
@@ -190,11 +201,10 @@ unsigned SubtargetEmitter::CollectAllItinClasses(std::ostream &OS,
   unsigned N = ItinClassList.size();
   for (unsigned i = 0; i < N; i++) {
     // Next itinerary class
-    Record *ItinClass = ItinClassList[i];
+    const Record *ItinClass = ItinClassList[i];
     // Get name of itinerary class
-    std::string Name = ItinClass->getName();
     // Assign itinerary class a unique number
-    ItinClassesMap[Name] = i;
+    ItinClassesMap[ItinClass->getName()] = i;
   }
   
   // Emit size of table
@@ -214,28 +224,26 @@ void SubtargetEmitter::FormItineraryString(Record *ItinData,
                                            std::string &ItinString,
                                            unsigned &NStages) {
   // Get states list
-  std::vector<Record*> StageList = ItinData->getValueAsListOfDefs("Stages");
+  const std::vector<Record*> &StageList =
+    ItinData->getValueAsListOfDefs("Stages");
 
   // For each stage
   unsigned N = NStages = StageList.size();
   for (unsigned i = 0; i < N;) {
     // Next stage
-    Record *Stage = StageList[i];
+    const Record *Stage = StageList[i];
   
     // Form string as ,{ cycles, u1 | u2 | ... | un }
     int Cycles = Stage->getValueAsInt("Cycles");
     ItinString += "  { " + itostr(Cycles) + ", ";
     
     // Get unit list
-    std::vector<Record*> UnitList = Stage->getValueAsListOfDefs("Units");
+    const std::vector<Record*> &UnitList = Stage->getValueAsListOfDefs("Units");
     
     // For each unit
     for (unsigned j = 0, M = UnitList.size(); j < M;) {
-      // Next unit
-      Record *Unit = UnitList[j];
-      
       // Add name and bitwise or
-      ItinString += Unit->getName();
+      ItinString += UnitList[j]->getName();
       if (++j < M) ItinString += " | ";
     }
     
@@ -271,7 +279,7 @@ void SubtargetEmitter::EmitStageData(std::ostream &OS,
     Record *Proc = ProcItinList[i];
     
     // Get processor itinerary name
-    std::string Name = Proc->getName();
+    const std::string &Name = Proc->getName();
     
     // Skip default
     if (Name == "NoItineraries") continue;
@@ -308,7 +316,7 @@ void SubtargetEmitter::EmitStageData(std::ostream &OS,
       InstrItinerary Intinerary = { Find, Find + NStages };
 
       // Locate where to inject into processor itinerary table
-      std::string Name = ItinData->getValueAsDef("TheClass")->getName();
+      const std::string &Name = ItinData->getValueAsDef("TheClass")->getName();
       Find = ItinClassesMap[Name];
       
       // Inject - empty slots will be 0, 0
@@ -347,7 +355,7 @@ void SubtargetEmitter::EmitProcessorData(std::ostream &OS,
     Record *Itin = Itins[i];
 
     // Get processor itinerary name
-    std::string Name = Itin->getName();
+    const std::string &Name = Itin->getName();
     
     // Skip default
     if (Name == "NoItineraries") continue;
@@ -398,8 +406,9 @@ void SubtargetEmitter::EmitProcessorLookup(std::ostream &OS) {
     // Next processor
     Record *Processor = ProcessorList[i];
 
-    std::string Name = Processor->getValueAsString("Name");
-    std::string ProcItin = Processor->getValueAsDef("ProcItin")->getName();
+    const std::string &Name = Processor->getValueAsString("Name");
+    const std::string &ProcItin =
+      Processor->getValueAsDef("ProcItin")->getName();
     
     // Emit as { "cpu", procinit },
     OS << "  { "
@@ -456,33 +465,32 @@ void SubtargetEmitter::ParseFeaturesFunction(std::ostream &OS) {
   std::sort(Features.begin(), Features.end(), LessRecord());
 
   OS << "// ParseSubtargetFeatures - Parses features string setting specified\n" 
-        "// subtarget options.\n" 
-        "void llvm::";
+     << "// subtarget options.\n" 
+     << "void llvm::";
   OS << Target;
   OS << "Subtarget::ParseSubtargetFeatures(const std::string &FS,\n"
-        "                                  const std::string &CPU) {\n"
-        "  SubtargetFeatures Features(FS);\n"
-        "  Features.setCPUIfNone(CPU);\n"
-        "  uint32_t Bits =  Features.getBits(SubTypeKV, SubTypeKVSize,\n"
-        "                                    FeatureKV, FeatureKVSize);\n";
-        
+     << "                                  const std::string &CPU) {\n"
+     << "  SubtargetFeatures Features(FS);\n"
+     << "  Features.setCPUIfNone(CPU);\n"
+     << "  uint32_t Bits =  Features.getBits(SubTypeKV, SubTypeKVSize,\n"
+     << "                                    FeatureKV, FeatureKVSize);\n";
+
   for (unsigned i = 0; i < Features.size(); i++) {
     // Next record
     Record *R = Features[i];
-    std::string Instance = R->getName();
-    std::string Name = R->getValueAsString("Name");
-    std::string Value = R->getValueAsString("Value");
-    std::string Attribute = R->getValueAsString("Attribute");
+    const std::string &Instance = R->getName();
+    const std::string &Value = R->getValueAsString("Value");
+    const std::string &Attribute = R->getValueAsString("Attribute");
 
     OS << "  if ((Bits & " << Instance << ") != 0) "
        << Attribute << " = " << Value << ";\n";
   }
-  
+
   if (HasItineraries) {
     OS << "\n"
        << "  InstrItinerary *Itinerary = (InstrItinerary *)"
-                        "Features.getInfo(ProcItinKV, ProcItinKVSize);\n"
-          "  InstrItins = InstrItineraryData(Stages, Itinerary);\n";
+       <<              "Features.getInfo(ProcItinKV, ProcItinKVSize);\n"
+       << "  InstrItins = InstrItineraryData(Stages, Itinerary);\n";
   }
   
   OS << "}\n";