From 28e607057cb87c6dadde0f4f32abf3adf32361e3 Mon Sep 17 00:00:00 2001
From: David Spickett <david.spickett@linaro.org>
Date: Mon, 6 Nov 2023 23:32:24 +0000
Subject: [PATCH] LLVM TableGen: Improve docstring for Actions Override and add
 example (#5711)

A majority of the actions/backends expect to find certain classes and
definitions in the source code. There's no canonical reference for this
so it's a combination of incomplete docs and the actual uses in
llvm-project.

(most of the time I expect people will come from llvm-project to
experiment, rather than the other way around)

I've added an example that uses the Searchable Tables backend.

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---
 examples/tablegen/searchable_tables.td | 20 ++++++++++++++++++++
 lib/compilers/tablegen.ts              |  8 +++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 examples/tablegen/searchable_tables.td

diff --git a/examples/tablegen/searchable_tables.td b/examples/tablegen/searchable_tables.td
new file mode 100644
index 000000000..605464bb8
--- /dev/null
+++ b/examples/tablegen/searchable_tables.td
@@ -0,0 +1,20 @@
+// This example uses the Searchable Tables backend, aka --gen-searchable-tables.
+// To choose the backend, select it as the "Action" in the "Overrides" menu,
+// or add "--gen-searchable-tables" to the compiler options.
+// For more details:
+// https://llvm.org/docs/TableGen/BackEnds.html#searchabletables-reference
+
+include "llvm/TableGen/SearchableTable.td"
+
+class Pair<string name, int value> : SearchableTable {
+  let SearchableFields = ["Name", "Value"];
+  let EnumValueField = "Value";
+
+  string Name = name;
+  bits<2> Value = value;
+}
+
+def : Pair<"Example 0", 0b00>;
+def : Pair<"Example 1", 0b01>;
+def : Pair<"Example 2", 0b10>;
+def : Pair<"Example 3", 0b11>;
\ No newline at end of file
diff --git a/lib/compilers/tablegen.ts b/lib/compilers/tablegen.ts
index 1ce51f2cc..04acf3ce0 100644
--- a/lib/compilers/tablegen.ts
+++ b/lib/compilers/tablegen.ts
@@ -32,7 +32,13 @@ export class TableGenCompiler extends BaseCompiler {
                 display_title: 'Action',
                 description:
                     'The action to perform, which is the backend you wish to ' +
-                    'run. By default, the records are just printed as text.',
+                    'run. By default, the records are just printed as text. ' +
+                    'Many backends expect to find certain classes and defnitions ' +
+                    'in your source code. You may find details of those in the ' +
+                    '<a href="https://llvm.org/docs/TableGen/BackEnds.html" target="_blank">documentation</a>, ' +
+                    'but if not, refer to use of the backend in the ' +
+                    '<a href="https://github.com/llvm/llvm-project" target="_blank">LLVM Project</a> ' +
+                    'by searching for the command line name e.g. "gen-attrs".',
                 flags: ['<value>'],
                 values: possibleActions,
                 default: '--print-records',