[mlir][docgen] Add ops source link (#73657)

This patch suggests to change two things. Firstly, it adds a source link
above the generated operations docs (above the `emitOpDoc` calls). This
link will point directly to the source TableGen file for the group of
operations. For example, for the current
[`amdgpu`](https://mlir.llvm.org/docs/Dialects/AMDGPU/) page, the link
will add a source link below the "Operation definition" heading pointing
to
[`mlir/include/mlir/Dialect/AMDGPU/IR/AMDGPU.td`](https://github.com/llvm/llvm-project/blob/main/mlir/include/mlir/Dialect/AMDGPU/IR/AMDGPU.td).
The link is wrapped in a "op-definitions-source-link" class which could
allow for custom styling, but it also looks reasonable without custom
styling I think:

![afbeelding](https://github.com/llvm/llvm-project/assets/20724914/7c0e59b9-b14b-4f5d-a671-c87e857a7b03)

Secondly, this patch simplifies the header names such as "Operation
definition" and "Attribute definition" to "Operations" and "Attributes"
respectively. This is in line with manually defined subheadings on pages
such as the one for the
[`vector`](https://mlir.llvm.org/docs/Dialects/Vector/#operations)
dialect.

mlir/test/mlir-tblgen/gen-dialect-doc.td

@@ -85,7 +85,7 @@ def TestTypeDefParams : TypeDef<Test_Dialect, "TestTypeDefParams"> {
 // CHECK: Interfaces: NoMemoryEffect (MemoryEffectOpInterface)
 // CHECK: Effects: MemoryEffects::Effect{}
 
-// CHECK: ## Attribute constraint definition
+// CHECK: ## Attribute constraints
 // CHECK: ### attribute summary
 // CHECK: attribute description
 
@@ -97,7 +97,7 @@ def TestTypeDefParams : TypeDef<Test_Dialect, "TestTypeDefParams"> {
 // CHECK: Syntax:
 // CHECK: #test.test_attr_def_params
 
-// CHECK: ## Type constraint definition
+// CHECK: ## Type constraints
 // CHECK: ### type summary
 // CHECK: type description
 

mlir/tools/mlir-tblgen/OpDocGen.cpp

@@ -265,10 +265,22 @@ static void emitOpDoc(const Operator &op, raw_ostream &os) {
   os << "\n";
 }
 
+static void emitSourceLink(StringRef inputFilename, raw_ostream &os) {
+  size_t pathBegin = inputFilename.find("mlir/include/mlir/");
+  if (pathBegin == StringRef::npos)
+    return;
+
+  StringRef inputFromMlirInclude = inputFilename.substr(pathBegin);
+
+  os << "[source](https://github.com/llvm/llvm-project/blob/main/"
+     << inputFromMlirInclude << ")\n\n";
+}
+
 static void emitOpDoc(const RecordKeeper &recordKeeper, raw_ostream &os) {
   auto opDefs = getRequestedOpDefinitions(recordKeeper);
 
   os << "<!-- Autogenerated by mlir-tblgen; don't manually edit -->\n";
+  emitSourceLink(recordKeeper.getInputFilename(), os);
   for (const llvm::Record *opDef : opDefs)
     emitOpDoc(Operator(opDef), os);
 }
@@ -392,12 +404,13 @@ static void maybeNest(bool nest, llvm::function_ref<void(raw_ostream &os)> fn,
   }
 }
 
-static void emitBlock(ArrayRef<Attribute> attributes,
+static void emitBlock(ArrayRef<Attribute> attributes, StringRef inputFilename,
                       ArrayRef<AttrDef> attrDefs, ArrayRef<OpDocGroup> ops,
                       ArrayRef<Type> types, ArrayRef<TypeDef> typeDefs,
                       raw_ostream &os) {
   if (!ops.empty()) {
-    os << "## Operation definition\n\n";
+    os << "## Operations\n\n";
+    emitSourceLink(inputFilename, os);
     for (const OpDocGroup &grouping : ops) {
       bool nested = !grouping.summary.empty();
       maybeNest(
@@ -417,32 +430,32 @@ static void emitBlock(ArrayRef<Attribute> attributes,
   }
 
   if (!attributes.empty()) {
-    os << "## Attribute constraint definition\n\n";
+    os << "## Attribute constraints\n\n";
     for (const Attribute &attr : attributes)
       emitAttrDoc(attr, os);
   }
 
   if (!attrDefs.empty()) {
-    os << "## Attribute definition\n\n";
+    os << "## Attributes\n\n";
     for (const AttrDef &def : attrDefs)
       emitAttrOrTypeDefDoc(def, os);
   }
 
   // TODO: Add link between use and def for types
   if (!types.empty()) {
-    os << "## Type constraint definition\n\n";
+    os << "## Type constraints\n\n";
     for (const Type &type : types)
       emitTypeDoc(type, os);
   }
 
   if (!typeDefs.empty()) {
-    os << "## Type definition\n\n";
+    os << "## Types\n\n";
     for (const TypeDef &def : typeDefs)
       emitAttrOrTypeDefDoc(def, os);
   }
 }
 
-static void emitDialectDoc(const Dialect &dialect,
+static void emitDialectDoc(const Dialect &dialect, StringRef inputFilename,
                            ArrayRef<Attribute> attributes,
                            ArrayRef<AttrDef> attrDefs, ArrayRef<OpDocGroup> ops,
                            ArrayRef<Type> types, ArrayRef<TypeDef> typeDefs,
@@ -456,7 +469,7 @@ static void emitDialectDoc(const Dialect &dialect,
   if (!r.match(dialect.getDescription()))
     os << "[TOC]\n\n";
 
-  emitBlock(attributes, attrDefs, ops, types, typeDefs, os);
+  emitBlock(attributes, inputFilename, attrDefs, ops, types, typeDefs, os);
 }
 
 static bool emitDialectDoc(const RecordKeeper &recordKeeper, raw_ostream &os) {
@@ -536,8 +549,9 @@ static bool emitDialectDoc(const RecordKeeper &recordKeeper, raw_ostream &os) {
             });
 
   os << "<!-- Autogenerated by mlir-tblgen; don't manually edit -->\n";
-  emitDialectDoc(*dialect, dialectAttrs, dialectAttrDefs, dialectOps,
-                 dialectTypes, dialectTypeDefs, os);
+  emitDialectDoc(*dialect, recordKeeper.getInputFilename(), dialectAttrs,
+                 dialectAttrDefs, dialectOps, dialectTypes, dialectTypeDefs,
+                 os);
   return false;
 }