Add CodeGen C API (#931)

I'd like to experiment with the codegen feature (currently experimental)
and need a public C API for this.

This PR addresses this.

CMakeLists.txt

@@ -143,6 +143,9 @@ endif()
 
 if(LUAU_NATIVE)
     target_compile_definitions(Luau.VM PUBLIC LUA_CUSTOM_EXECUTION=1)
+    if(LUAU_EXTERN_C)
+        target_compile_definitions(Luau.CodeGen PUBLIC LUACODEGEN_API=extern\"C\")
+    endif()
 endif()
 
 if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC" AND MSVC_VERSION GREATER_EQUAL 1924)

CodeGen/include/luacodegen.h

@@ -0,0 +1,18 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+#pragma once
+
+// Can be used to reconfigure visibility/exports for public APIs
+#ifndef LUACODEGEN_API
+#define LUACODEGEN_API extern
+#endif
+
+struct lua_State;
+
+// returns 1 if Luau code generator is supported, 0 otherwise
+LUACODEGEN_API int luau_codegen_supported();
+
+// create an instance of Luau code generator. you must check that this feature is supported using luau_codegen_supported().
+LUACODEGEN_API void luau_codegen_create(lua_State* L);
+
+// build target function and all inner functions
+LUACODEGEN_API void luau_codegen_compile(lua_State* L, int idx);

CodeGen/src/lcodegen.cpp

@@ -0,0 +1,21 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+#include "luacodegen.h"
+
+#include "Luau/CodeGen.h"
+
+#include "lapi.h"
+
+int luau_codegen_supported()
+{
+    return Luau::CodeGen::isSupported();
+}
+
+void luau_codegen_create(lua_State* L)
+{
+    Luau::CodeGen::create(L);
+}
+
+void luau_codegen_compile(lua_State* L, int idx)
+{
+    Luau::CodeGen::compile(L, idx);
+}

Sources.cmake

@@ -79,6 +79,7 @@ target_sources(Luau.CodeGen PRIVATE
     CodeGen/include/Luau/UnwindBuilder.h
     CodeGen/include/Luau/UnwindBuilderDwarf2.h
     CodeGen/include/Luau/UnwindBuilderWin.h
+    CodeGen/include/luacodegen.h
 
     CodeGen/src/AssemblyBuilderA64.cpp
     CodeGen/src/AssemblyBuilderX64.cpp
@@ -104,6 +105,7 @@ target_sources(Luau.CodeGen PRIVATE
     CodeGen/src/IrTranslation.cpp
     CodeGen/src/IrUtils.cpp
     CodeGen/src/IrValueLocationTracking.cpp
+    CodeGen/src/lcodegen.cpp
     CodeGen/src/NativeState.cpp
     CodeGen/src/OptimizeConstProp.cpp
     CodeGen/src/OptimizeFinalX64.cpp

tests/Conformance.test.cpp

@@ -2,13 +2,13 @@
 #include "lua.h"
 #include "lualib.h"
 #include "luacode.h"
+#include "luacodegen.h"
 
 #include "Luau/BuiltinDefinitions.h"
 #include "Luau/ModuleResolver.h"
 #include "Luau/TypeInfer.h"
 #include "Luau/StringUtils.h"
 #include "Luau/BytecodeBuilder.h"
-#include "Luau/CodeGen.h"
 #include "Luau/Frontend.h"
 
 #include "doctest.h"
@@ -159,8 +159,8 @@ static StateRef runConformance(const char* name, void (*setup)(lua_State* L) = n
     StateRef globalState(initialLuaState, lua_close);
     lua_State* L = globalState.get();
 
-    if (codegen && !skipCodegen && Luau::CodeGen::isSupported())
-        Luau::CodeGen::create(L);
+    if (codegen && !skipCodegen && luau_codegen_supported())
+        luau_codegen_create(L);
 
     luaL_openlibs(L);
 
@@ -213,8 +213,8 @@ static StateRef runConformance(const char* name, void (*setup)(lua_State* L) = n
     int result = luau_load(L, chunkname.c_str(), bytecode, bytecodeSize, 0);
     free(bytecode);
 
-    if (result == 0 && codegen && !skipCodegen && Luau::CodeGen::isSupported())
-        Luau::CodeGen::compile(L, -1);
+    if (result == 0 && codegen && !skipCodegen && luau_codegen_supported())
+        luau_codegen_compile(L, -1);
 
     int status = (result == 0) ? lua_resume(L, nullptr, 0) : LUA_ERRSYNTAX;
 
@@ -1679,8 +1679,8 @@ TEST_CASE("HugeFunction")
     StateRef globalState(luaL_newstate(), lua_close);
     lua_State* L = globalState.get();
 
-    if (codegen && Luau::CodeGen::isSupported())
-        Luau::CodeGen::create(L);
+    if (codegen && luau_codegen_supported())
+        luau_codegen_create(L);
 
     luaL_openlibs(L);
     luaL_sandbox(L);
@@ -1693,8 +1693,8 @@ TEST_CASE("HugeFunction")
 
     REQUIRE(result == 0);
 
-    if (codegen && Luau::CodeGen::isSupported())
-        Luau::CodeGen::compile(L, -1);
+    if (codegen && luau_codegen_supported())
+        luau_codegen_compile(L, -1);
 
     int status = lua_resume(L, nullptr, 0);
     REQUIRE(status == 0);