[NFC][InstrInfoEmitter] Include location of inst definition in comment

Print the source location of the instruction definition in comment
next to the enum value for each instruction. To make this more
readable, change formatting of the instruction enums to be better
aligned.

Author: jurahul

llvm/utils/TableGen/Common/CodeGenInstruction.h

@@ -320,6 +320,8 @@ class CodeGenInstruction {
     return RV && isa<DagInit>(RV->getValue());
   }
 
+  StringRef getName() const { return TheDef->getName(); }
+
 private:
   bool isOperandImpl(StringRef OpListName, unsigned i,
                      StringRef PropertyName) const;

llvm/utils/TableGen/InstrInfoEmitter.cpp

@@ -25,6 +25,8 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/Casting.h"
+#include "llvm/Support/FormattedStream.h"
+#include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Record.h"
@@ -1289,8 +1291,9 @@ void InstrInfoEmitter::emitRecord(
 
 // emitEnums - Print out enum values for all of the instructions.
 void InstrInfoEmitter::emitEnums(
-    raw_ostream &OS,
+    raw_ostream &RawOS,
     ArrayRef<const CodeGenInstruction *> NumberedInstructions) {
+  formatted_raw_ostream OS(RawOS);
   OS << "#ifdef GET_INSTRINFO_ENUM\n";
   OS << "#undef GET_INSTRINFO_ENUM\n";
 
@@ -1302,18 +1305,29 @@ void InstrInfoEmitter::emitEnums(
 
   OS << "namespace llvm::" << Namespace << " {\n";
 
+  auto II = llvm::max_element(
+      NumberedInstructions,
+      [](const CodeGenInstruction *InstA, const CodeGenInstruction *InstB) {
+        return InstA->getName().size() < InstB->getName().size();
+      });
+  size_t MaxNameSize = (*II)->getName().size();
+
   OS << "  enum {\n";
-  for (const CodeGenInstruction *Inst : NumberedInstructions)
-    OS << "    " << Inst->TheDef->getName()
-       << "\t= " << Target.getInstrIntValue(Inst->TheDef) << ",\n";
+  for (const CodeGenInstruction *Inst : NumberedInstructions) {
+    OS << "    " << Inst->TheDef->getName();
+    OS.PadToColumn(MaxNameSize + 5);
+    OS << " = " << Target.getInstrIntValue(Inst->TheDef) << ", // (";
+    OS << SrcMgr.getFormattedLocationNoOffset(Inst->TheDef->getLoc().front())
+       << ")\n";
+  }
   OS << "    INSTRUCTION_LIST_END = " << NumberedInstructions.size() << '\n';
-  OS << "  };\n\n";
+  OS << "  };\n";
   OS << "} // end namespace llvm::" << Namespace << '\n';
   OS << "#endif // GET_INSTRINFO_ENUM\n\n";
 
   OS << "#ifdef GET_INSTRINFO_SCHED_ENUM\n";
   OS << "#undef GET_INSTRINFO_SCHED_ENUM\n";
-  OS << "namespace llvm::" << Namespace << "::Sched {\n\n";
+  OS << "namespace llvm::" << Namespace << "::Sched {\n";
   OS << "  enum {\n";
   auto ExplictClasses = SchedModels.explicitSchedClasses();
   for (const auto &[Idx, Class] : enumerate(ExplictClasses))