[RFC][Patch 2/3] Add a MCSubtargetInfo hook to resolve variant scheduling classes.

This patch is the second of a sequence of three patches related to LLVM-dev RFC
"MC support for varinat scheduling classes".
https://lists.llvm.org/pipermail/llvm-dev/2018-May/123181.html

The goal of this patch is to enable the resolution of variant classes in MC with
the help of a new method named `MCSubtargetInfo::resolveVariantSchedClass()`.

This patch also teaches the SubtargetEmitter how to automatically generate the
definition of method resolveVariantSchedClass().  That definition is emitted
within a sub-class of MCSubtargetInfo named XXXGenMCSubtargetInfo (where XXX is
the name of the Target).

Differential Revision: https://reviews.llvm.org/D47077

llvm-svn: 333286

2 files changed, 79 insertions, 1 deletions

diff --git a/llvm/utils/TableGen/InstrInfoEmitter.cpp b/llvm/utils/TableGen/InstrInfoEmitter.cpp
index 61c3f1d2bb4..0aff1aa6f94 100644
--- a/llvm/utils/TableGen/InstrInfoEmitter.cpp
+++ b/llvm/utils/TableGen/InstrInfoEmitter.cpp
@@ -67,6 +67,10 @@ private:
   /// See file llvm/Target/TargetInstPredicates.td for a description of what is
   /// a TIIPredicate and how to use it.
   void emitTIIHelperMethods(raw_ostream &OS);
+
+  /// Expand TIIPredicate definitions to functions that accept a const MCInst
+  /// reference.
+  void emitMCIIHelperMethods(raw_ostream &OS);
   void emitRecord(const CodeGenInstruction &Inst, unsigned Num,
                   Record *InstrInfo,
                   std::map<std::vector<Record*>, unsigned> &EL,
@@ -347,6 +351,55 @@ void InstrInfoEmitter::emitOperandTypesEnum(raw_ostream &OS,
   OS << "#endif // GET_INSTRINFO_OPERAND_TYPES_ENUM\n\n";
 }
 
+void InstrInfoEmitter::emitMCIIHelperMethods(raw_ostream &OS) {
+  RecVec TIIPredicates = Records.getAllDerivedDefinitions("TIIPredicate");
+  if (TIIPredicates.empty())
+    return;
+
+  CodeGenTarget &Target = CDP.getTargetInfo();
+  const StringRef TargetName = Target.getName();
+  formatted_raw_ostream FOS(OS);
+
+  FOS << "#ifdef GET_GENINSTRINFO_MC_DECL\n";
+  FOS << "#undef GET_GENINSTRINFO_MC_DECL\n\n";
+
+  FOS << "namespace llvm {\n";
+  FOS << "class MCInst;\n\n";
+
+  FOS << "namespace " << TargetName << "_MC {\n\n";
+
+  for (const Record *Rec : TIIPredicates) {
+    FOS << "bool " << Rec->getValueAsString("FunctionName")
+        << "(const MCInst &MI);\n";
+  }
+
+  FOS << "\n} // end " << TargetName << "_MC namespace\n";
+  FOS << "} // end llvm namespace\n\n";
+
+  FOS << "#endif // GET_GENINSTRINFO_MC_DECL\n\n";
+
+  FOS << "#ifdef GET_GENINSTRINFO_MC_HELPERS\n";
+  FOS << "#undef GET_GENINSTRINFO_MC_HELPERS\n\n";
+
+  FOS << "namespace llvm {\n";
+  FOS << "namespace " << TargetName << "_MC {\n\n";
+
+  PredicateExpander PE;
+  PE.setExpandForMC(true);
+  for (const Record *Rec : TIIPredicates) {
+    FOS << "bool " << Rec->getValueAsString("FunctionName");
+    FOS << "(const MCInst &MI) {\n";
+    FOS << "  return ";
+    PE.expandPredicate(FOS, Rec->getValueAsDef("Pred"));
+    FOS << ";\n}\n";
+  }
+
+  FOS << "\n} // end " << TargetName << "_MC namespace\n";
+  FOS << "} // end llvm namespace\n\n";
+
+  FOS << "#endif // GET_GENISTRINFO_MC_HELPERS\n";
+}
+
 void InstrInfoEmitter::emitTIIHelperMethods(raw_ostream &OS) {
   RecVec TIIPredicates = Records.getAllDerivedDefinitions("TIIPredicate");
   if (TIIPredicates.empty())
@@ -490,6 +543,8 @@ void InstrInfoEmitter::run(raw_ostream &OS) {
   emitOperandNameMappings(OS, Target, NumberedInstructions);
 
   emitOperandTypesEnum(OS, Target);
+
+  emitMCIIHelperMethods(OS);
 }
 
 void InstrInfoEmitter::emitRecord(const CodeGenInstruction &Inst, unsigned Num,
diff --git a/llvm/utils/TableGen/SubtargetEmitter.cpp b/llvm/utils/TableGen/SubtargetEmitter.cpp
index d110f80766d..c90dbed3601 100644
--- a/llvm/utils/TableGen/SubtargetEmitter.cpp
+++ b/llvm/utils/TableGen/SubtargetEmitter.cpp
@@ -115,6 +115,7 @@ class SubtargetEmitter {
   void EmitSchedModelHelpers(const std::string &ClassName, raw_ostream &OS);
   void emitSchedModelHelpersImpl(raw_ostream &OS,
                                  bool OnlyExpandMCInstPredicates = false);
+  void emitGenMCSubtargetInfo(raw_ostream &OS);
 
   void EmitSchedModel(raw_ostream &OS);
   void EmitHwModeCheck(const std::string &ClassName, raw_ostream &OS);
@@ -1645,6 +1646,26 @@ void SubtargetEmitter::ParseFeaturesFunction(raw_ostream &OS,
   OS << "}\n";
 }
 
+void SubtargetEmitter::emitGenMCSubtargetInfo(raw_ostream &OS) {
+  OS << "struct " << Target
+     << "GenMCSubtargetInfo : public MCSubtargetInfo {\n";
+  OS << "  " << Target << "GenMCSubtargetInfo(const Triple &TT, \n"
+     << "    StringRef CPU, StringRef FS, ArrayRef<SubtargetFeatureKV> PF,\n"
+     << "    ArrayRef<SubtargetFeatureKV> PD,\n"
+     << "    const SubtargetInfoKV *ProcSched,\n"
+     << "    const MCWriteProcResEntry *WPR,\n"
+     << "    const MCWriteLatencyEntry *WL,\n"
+     << "    const MCReadAdvanceEntry *RA, const InstrStage *IS,\n"
+     << "    const unsigned *OC, const unsigned *FP) :\n"
+     << "      MCSubtargetInfo(TT, CPU, FS, PF, PD, ProcSched,\n"
+     << "                      WPR, WL, RA, IS, OC, FP) { }\n\n"
+     << "  unsigned resolveVariantSchedClass(unsigned SchedClass,\n"
+     << "      const MCInst *MI, unsigned CPUID) const override {\n";
+  emitSchedModelHelpersImpl(OS, /* OnlyExpandMCPredicates */ true);
+  OS << "  }\n";
+  OS << "};\n";
+}
+
 //
 // SubtargetEmitter::run - Main subtarget enumeration emitter.
 //
@@ -1677,10 +1698,12 @@ void SubtargetEmitter::run(raw_ostream &OS) {
 #endif
 
   // MCInstrInfo initialization routine.
+  emitGenMCSubtargetInfo(OS);
+
   OS << "\nstatic inline MCSubtargetInfo *create" << Target
      << "MCSubtargetInfoImpl("
      << "const Triple &TT, StringRef CPU, StringRef FS) {\n";
-  OS << "  return new MCSubtargetInfo(TT, CPU, FS, ";
+  OS << "  return new " << Target << "GenMCSubtargetInfo(TT, CPU, FS, ";
   if (NumFeatures)
     OS << Target << "FeatureKV, ";
   else