[clang] [clang-repl] Improve flags responsible for generating shared wasm binaries (PR #116735)

[Anutosh Bhat via cfe-commits]

https://github.com/anutosh491 created https://github.com/llvm/llvm-project/pull/116735

There are a couple changes in this PR that help getting clang-repl to run in the browser. Using a jupyterlite instance for the example pasted below

1) Updating flags responsible for generating shared wasm binaries that need to be dynamically loaded Most Importantly as can be seen in the changes `shared` and `allow-undefined` are crucial.


![image](https://github.com/user-attachments/assets/1183fd44-8951-496a-899a-e4af39a48447)

2) While exiting we encounter this.


![image](https://github.com/user-attachments/assets/9487a3f4-7200-471d-ba88-09e98ccbc47a)


Now as can be seen here 

https://github.com/llvm/llvm-project/blob/cd418030de7ae75750bc4e48d1238baf03c675e5/clang/lib/Interpreter/Interpreter.cpp#L421-L430

We call cleanUP in the destructor. Now cleanUP through IncrementalExecutor tries to deinitialize the JIT which wasn't even intialized as runCtors in wasm.cpp is a no-op 

https://github.com/llvm/llvm-project/blob/cd418030de7ae75750bc4e48d1238baf03c675e5/clang/lib/Interpreter/IncrementalExecutor.cpp#L94-L101

https://github.com/llvm/llvm-project/blob/cd418030de7ae75750bc4e48d1238baf03c675e5/clang/lib/Interpreter/Wasm.cpp#L107-L109



>From 07371ceff88bbfce990f9bf284bd64b4bbfd851a Mon Sep 17 00:00:00 2001
From: anutosh491 <andersonbhat491 at gmail.com>
Date: Tue, 19 Nov 2024 08:37:36 +0530
Subject: [PATCH] Improve flags responsible for generating shared wasm binaries

---
 clang/lib/Interpreter/IncrementalExecutor.h |  2 +-
 clang/lib/Interpreter/Wasm.cpp              | 11 +++++++++--
 clang/lib/Interpreter/Wasm.h                |  1 +
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/clang/lib/Interpreter/IncrementalExecutor.h b/clang/lib/Interpreter/IncrementalExecutor.h
index 7954cde36588bd..dbd61f0b8b1ebb 100644
--- a/clang/lib/Interpreter/IncrementalExecutor.h
+++ b/clang/lib/Interpreter/IncrementalExecutor.h
@@ -56,7 +56,7 @@ class IncrementalExecutor {
   virtual llvm::Error addModule(PartialTranslationUnit &PTU);
   virtual llvm::Error removeModule(PartialTranslationUnit &PTU);
   virtual llvm::Error runCtors() const;
-  llvm::Error cleanUp();
+  virtual llvm::Error cleanUp();
   llvm::Expected<llvm::orc::ExecutorAddr>
   getSymbolAddress(llvm::StringRef Name, SymbolNameKind NameKind) const;
 
diff --git a/clang/lib/Interpreter/Wasm.cpp b/clang/lib/Interpreter/Wasm.cpp
index 1001410aa0f279..6f00bac8c0bc46 100644
--- a/clang/lib/Interpreter/Wasm.cpp
+++ b/clang/lib/Interpreter/Wasm.cpp
@@ -72,13 +72,14 @@ llvm::Error WasmIncrementalExecutor::addModule(PartialTranslationUnit &PTU) {
   OutputFile.close();
 
   std::vector<const char *> LinkerArgs = {"wasm-ld",
-                                          "-pie",
+                                          "-shared",
                                           "--import-memory",
                                           "--no-entry",
                                           "--export-all",
                                           "--experimental-pic",
-                                          "--no-export-dynamic",
+                                          "--export-dynamic",
                                           "--stack-first",
+                                          "--allow-undefined",
                                           OutputFileName.c_str(),
                                           "-o",
                                           OutputFileName.c_str()};
@@ -109,6 +110,12 @@ llvm::Error WasmIncrementalExecutor::runCtors() const {
   return llvm::Error::success();
 }
 
+llvm::Error WasmIncrementalExecutor::cleanUp() const {
+  // Can't call cleanUp through IncrementalExecutor as it
+  // tries to deinitialize JIT which hasn't been initialized
+  return llvm::Error::success();
+}
+
 WasmIncrementalExecutor::~WasmIncrementalExecutor() = default;
 
 } // namespace clang
diff --git a/clang/lib/Interpreter/Wasm.h b/clang/lib/Interpreter/Wasm.h
index b1fd88024f14d7..4632613326d39b 100644
--- a/clang/lib/Interpreter/Wasm.h
+++ b/clang/lib/Interpreter/Wasm.h
@@ -28,6 +28,7 @@ class WasmIncrementalExecutor : public IncrementalExecutor {
   llvm::Error addModule(PartialTranslationUnit &PTU) override;
   llvm::Error removeModule(PartialTranslationUnit &PTU) override;
   llvm::Error runCtors() const override;
+  llvm::Error cleanUp() override;
 
   ~WasmIncrementalExecutor() override;
 };