[NFC][TableGen] Add IfGuardEmitter and adopt it in InstrInfoEmitter

Add a RAII `IfGuardEmitter` to insert simple #if guards and adopt it in InstrInfoEmitter.

Author: jurahul

llvm/include/llvm/TableGen/CodeGenHelpers.h

@@ -46,6 +46,24 @@ class IfDefEmitter {
  bool LateUndef;
 };
 
+// Simple RAII helper for emitting #if guard. It emits:
+// <IfGuard> <Condition>
+// #endif // <Condition>
+class IfGuardEmitter {
+public:
+ IfGuardEmitter(raw_ostream &OS, StringRef Condition,
+ StringRef IfGuard = "#if")
+ : Condition(Condition.str()), OS(OS) {
+ OS << IfGuard << " " << Condition << "\n\n";
+ }
+
+ ~IfGuardEmitter() { OS << "\n#endif // " << Condition << "\n\n"; }
+
+private:
+ std::string Condition;
+ raw_ostream &OS;
+};
+
 // Simple RAII helper for emitting header include guard (ifndef-define-endif).
 class IncludeGuardEmitter {
 public:

llvm/utils/TableGen/InstrInfoEmitter.cpp

@@ -911,24 +911,23 @@ void InstrInfoEmitter::run(raw_ostream &OS) {
  }
  }
 
- OS << "#if defined(GET_INSTRINFO_MC_DESC) || "
- "defined(GET_INSTRINFO_CTOR_DTOR)\n";
-
- OS << "namespace llvm {\n\n";
-
- OS << "struct " << TargetName << "InstrTable {\n";
- OS << " MCInstrDesc Insts[" << NumberedInstructions.size() << "];\n";
- OS << " static_assert(alignof(MCInstrDesc) >= alignof(MCOperandInfo), "
- "\"Unwanted padding between Insts and OperandInfo\");\n";
- OS << " MCOperandInfo OperandInfo[" << OperandInfoSize << "];\n";
- OS << " static_assert(alignof(MCOperandInfo) >= alignof(MCPhysReg), "
- "\"Unwanted padding between OperandInfo and ImplicitOps\");\n";
- OS << " MCPhysReg ImplicitOps[" << std::max(ImplicitListSize, 1U) << "];\n";
- OS << "};\n\n";
-
- OS << "} // end namespace llvm\n";
- OS << "#endif // defined(GET_INSTRINFO_MC_DESC) || "
- "defined(GET_INSTRINFO_CTOR_DTOR)\n\n";
+ {
+ IfGuardEmitter IfGuard(
+ OS,
+ "defined(GET_INSTRINFO_MC_DESC) || defined(GET_INSTRINFO_CTOR_DTOR)");
+ NamespaceEmitter NS(OS, "llvm");
+
+ OS << "struct " << TargetName << "InstrTable {\n";
+ OS << " MCInstrDesc Insts[" << NumberedInstructions.size() << "];\n";
+ OS << " static_assert(alignof(MCInstrDesc) >= alignof(MCOperandInfo), "
+ "\"Unwanted padding between Insts and OperandInfo\");\n";
+ OS << " MCOperandInfo OperandInfo[" << OperandInfoSize << "];\n";
+ OS << " static_assert(alignof(MCOperandInfo) >= alignof(MCPhysReg), "
+ "\"Unwanted padding between OperandInfo and ImplicitOps\");\n";
+ OS << " MCPhysReg ImplicitOps[" << std::max(ImplicitListSize, 1U)
+ << "];\n";
+ OS << "};";
+ }
 
  const CodeGenRegBank &RegBank = Target.getRegBank();
  const CodeGenHwModes &CGH = Target.getHwModes();