[clang] Fix generation of wasm binaries while running clang-repl in browser (PR #117978)

[Anutosh Bhat via cfe-commits]

https://github.com/anutosh491 created https://github.com/llvm/llvm-project/pull/117978

None

>From 987f77db9d45dee264c60f434652131438784f6f Mon Sep 17 00:00:00 2001
From: anutosh491 <andersonbhat491 at gmail.com>
Date: Thu, 28 Nov 2024 14:02:00 +0530
Subject: [PATCH] Fix generation of wasm binaries while running clang-repl in
 browser

---
 clang/lib/Interpreter/CMakeLists.txt  |  2 +
 clang/lib/Interpreter/Interpreter.cpp |  1 +
 clang/lib/Interpreter/Wasm.cpp        | 57 ++++++++++++++++++++-------
 3 files changed, 45 insertions(+), 15 deletions(-)

diff --git a/clang/lib/Interpreter/CMakeLists.txt b/clang/lib/Interpreter/CMakeLists.txt
index df7ea82e0dada5..bf70cdfbee01e1 100644
--- a/clang/lib/Interpreter/CMakeLists.txt
+++ b/clang/lib/Interpreter/CMakeLists.txt
@@ -16,6 +16,7 @@ set(LLVM_LINK_COMPONENTS
 if (EMSCRIPTEN AND "lld" IN_LIST LLVM_ENABLE_PROJECTS)
   set(WASM_SRC Wasm.cpp)
   set(WASM_LINK lldWasm)
+  set(COMMON_LINK lldCommon)
 endif()
 
 add_clang_library(clangInterpreter
@@ -47,6 +48,7 @@ add_clang_library(clangInterpreter
   clangSema
   clangSerialization
   ${WASM_LINK}
+  ${COMMON_LINK}
   )
 
 if ((MINGW OR CYGWIN) AND BUILD_SHARED_LIBS)
diff --git a/clang/lib/Interpreter/Interpreter.cpp b/clang/lib/Interpreter/Interpreter.cpp
index 5dc67f6375098f..887b494ff98f19 100644
--- a/clang/lib/Interpreter/Interpreter.cpp
+++ b/clang/lib/Interpreter/Interpreter.cpp
@@ -201,6 +201,7 @@ IncrementalCompilerBuilder::CreateCpp() {
   Argv.push_back("-target");
   Argv.push_back("wasm32-unknown-emscripten");
   Argv.push_back("-shared");
+  Argv.push_back("-fvisibility=default");
 #endif
   Argv.insert(Argv.end(), UserArgs.begin(), UserArgs.end());
 
diff --git a/clang/lib/Interpreter/Wasm.cpp b/clang/lib/Interpreter/Wasm.cpp
index 79efbaa03982d0..0fd6ad509c2938 100644
--- a/clang/lib/Interpreter/Wasm.cpp
+++ b/clang/lib/Interpreter/Wasm.cpp
@@ -23,6 +23,31 @@
 #include <string>
 
 namespace lld {
+enum Flavor {
+  Invalid,
+  Gnu,     // -flavor gnu
+  MinGW,   // -flavor gnu MinGW
+  WinLink, // -flavor link
+  Darwin,  // -flavor darwin
+  Wasm,    // -flavor wasm
+};
+
+using Driver = bool (*)(llvm::ArrayRef<const char *>, llvm::raw_ostream &,
+                        llvm::raw_ostream &, bool, bool);
+
+struct DriverDef {
+  Flavor f;
+  Driver d;
+};
+
+struct Result {
+    int retCode;
+    bool canRunAgain;
+};
+
+Result lldMain(llvm::ArrayRef<const char *> args, llvm::raw_ostream &stdoutOS,
+                llvm::raw_ostream &stderrOS, llvm::ArrayRef<DriverDef> drivers);
+
 namespace wasm {
 bool link(llvm::ArrayRef<const char *> args, llvm::raw_ostream &stdoutOS,
           llvm::raw_ostream &stderrOS, bool exitEarly, bool disableOutput);
@@ -51,45 +76,47 @@ llvm::Error WasmIncrementalExecutor::addModule(PartialTranslationUnit &PTU) {
   llvm::TargetMachine *TargetMachine = Target->createTargetMachine(
       PTU.TheModule->getTargetTriple(), "", "", TO, llvm::Reloc::Model::PIC_);
   PTU.TheModule->setDataLayout(TargetMachine->createDataLayout());
-  std::string OutputFileName = PTU.TheModule->getName().str() + ".wasm";
+  std::string ObjectFileName = PTU.TheModule->getName().str() + ".o";  // For the wasm object
+  std::string BinaryFileName = PTU.TheModule->getName().str() + ".wasm";  // For the wasm binary
 
   std::error_code Error;
-  llvm::raw_fd_ostream OutputFile(llvm::StringRef(OutputFileName), Error);
+  llvm::raw_fd_ostream ObjectFileOutput(llvm::StringRef(ObjectFileName), Error);
 
   llvm::legacy::PassManager PM;
-  if (TargetMachine->addPassesToEmitFile(PM, OutputFile, nullptr,
+  if (TargetMachine->addPassesToEmitFile(PM, ObjectFileOutput, nullptr,
                                          llvm::CodeGenFileType::ObjectFile)) {
     return llvm::make_error<llvm::StringError>(
         "Wasm backend cannot produce object.", llvm::inconvertibleErrorCode());
   }
 
   if (!PM.run(*PTU.TheModule)) {
-
     return llvm::make_error<llvm::StringError>("Failed to emit Wasm object.",
                                                llvm::inconvertibleErrorCode());
   }
 
-  OutputFile.close();
+  ObjectFileOutput.close();
 
   std::vector<const char *> LinkerArgs = {"wasm-ld",
                                           "-shared",
                                           "--import-memory",
-                                          "--no-entry",
-                                          "--export-all",
                                           "--experimental-pic",
                                           "--stack-first",
                                           "--allow-undefined",
-                                          OutputFileName.c_str(),
+                                          ObjectFileName.c_str(),
                                           "-o",
-                                          OutputFileName.c_str()};
-  int Result =
-      lld::wasm::link(LinkerArgs, llvm::outs(), llvm::errs(), false, false);
-  if (!Result)
+                                          BinaryFileName.c_str()};
+
+  const lld::DriverDef WasmDriver = {lld::Flavor::Wasm, &lld::wasm::link};
+  std::vector<lld::DriverDef> WasmDriverArgs;
+  WasmDriverArgs.push_back(WasmDriver);
+  lld::Result Result = lld::lldMain(LinkerArgs, llvm::outs(), llvm::errs(), WasmDriverArgs);
+
+  if (Result.retCode != 0)
     return llvm::make_error<llvm::StringError>(
         "Failed to link incremental module", llvm::inconvertibleErrorCode());
 
   void *LoadedLibModule =
-      dlopen(OutputFileName.c_str(), RTLD_NOW | RTLD_GLOBAL);
+      dlopen(BinaryFileName.c_str(), RTLD_NOW | RTLD_GLOBAL);
   if (LoadedLibModule == nullptr) {
     llvm::errs() << dlerror() << '\n';
     return llvm::make_error<llvm::StringError>(
@@ -109,7 +136,7 @@ llvm::Error WasmIncrementalExecutor::runCtors() const {
   return llvm::Error::success();
 }
 
-llvm::Error WasmIncrementalExecutor::cleanUp() const {
+llvm::Error WasmIncrementalExecutor::cleanUp() {
   // Can't call cleanUp through IncrementalExecutor as it
   // tries to deinitialize JIT which hasn't been initialized
   return llvm::Error::success();
@@ -117,4 +144,4 @@ llvm::Error WasmIncrementalExecutor::cleanUp() const {
 
 WasmIncrementalExecutor::~WasmIncrementalExecutor() = default;
 
-} // namespace clang
+} // namespace clang
\ No newline at end of file