Rename Emscripten EHSjLj functions in wasm backend (#3191)

Now that we are renaming invoke wrappers and `emscripten_longjmp_jmpbuf`
in the wasm backend, this deletes all related renaming routines and
relevant tests. Depends on #3192.

Addresses: #3043 and #3081

Companions:
https://reviews.llvm.org/D88697
emscripten-core/emscripten#12399

Author: aheejin

src/passes/GenerateDynCalls.cpp

@@ -55,7 +55,8 @@ struct GenerateDynCalls : public WalkerPass<PostWalker<GenerateDynCalls>> {
 
   void visitFunction(Function* func) {
     // Generate dynCalls for invokes
-    if (func->imported() && func->base.startsWith("invoke_")) {
+    if (func->imported() && func->module == ENV &&
+        func->base.startsWith("invoke_")) {
       Signature sig = func->sig;
       // The first parameter is a pointer to the original function that's called
       // by the invoke, so skip it

src/passes/PostEmscripten.cpp

@@ -78,31 +78,13 @@ struct OptimizeCalls : public WalkerPass<PostWalker<OptimizeCalls>> {
 
 struct PostEmscripten : public Pass {
   void run(PassRunner* runner, Module* module) override {
-    // Optimize imports
-    optimizeImports(runner, module);
-
     // Optimize calls
     OptimizeCalls().run(runner, module);
 
     // Optimize exceptions
     optimizeExceptions(runner, module);
   }
 
-  void optimizeImports(PassRunner* runner, Module* module) {
-    // Calling emscripten_longjmp_jmpbuf is the same as emscripten_longjmp.
-    Name EMSCRIPTEN_LONGJMP("emscripten_longjmp");
-    Name EMSCRIPTEN_LONGJMP_JMPBUF("emscripten_longjmp_jmpbuf");
-    ImportInfo info(*module);
-    auto* emscripten_longjmp =
-      info.getImportedFunction(ENV, EMSCRIPTEN_LONGJMP);
-    auto* emscripten_longjmp_jmpbuf =
-      info.getImportedFunction(ENV, EMSCRIPTEN_LONGJMP_JMPBUF);
-    if (emscripten_longjmp && emscripten_longjmp_jmpbuf) {
-      // Both exist, so it is worth renaming so that we have only one.
-      emscripten_longjmp_jmpbuf->base = EMSCRIPTEN_LONGJMP;
-    }
-  }
-
   // Optimize exceptions (and setjmp) by removing unnecessary invoke* calls.
   // An invoke is a call to JS with a function pointer; JS does a try-catch
   // and calls the pointer, catching and reporting any error. If we know no

src/tools/wasm-emscripten-finalize.cpp

@@ -259,8 +259,6 @@ int main(int argc, const char* argv[]) {
   generator.onlyI64DynCalls = onlyI64DynCalls;
   generator.noDynCalls = noDynCalls;
 
-  generator.fixInvokeFunctionNames();
-
   std::vector<Name> initializerFunctions;
 
   // The wasm backend emits "__indirect_function_table" as the import name for

src/wasm/wasm-emscripten.cpp

@@ -487,134 +487,6 @@ EmJsWalker fixEmJsFuncsAndReturnWalker(Module& wasm) {
   return walker;
 }
 
-// Fixes function name hacks caused by LLVM exception & setjmp/longjmp
-// handling pass for wasm.
-// This does two things:
-// 1. Change emscripten_longjmp_jmpbuf to emscripten_longjmp.
-//    In setjmp/longjmp handling pass in wasm backend, what we want to do is
-//    to change all function calls to longjmp to calls to emscripten_longjmp.
-//    Because we replace all calls to longjmp to emscripten_longjmp, the
-//    signature of that function should be the same as longjmp:
-//    emscripten_longjmp(jmp_buf, int)
-//    But after calling a function that might longjmp, while we test whether
-//    a longjmp occurred, we have to load an int address value and call
-//    emscripten_longjmp again with that address as the first argument. (Refer
-//    to lib/Target/WebAssembly/WebAssemblyEmscriptenEHSjLj.cpp in LLVM for
-//    details.)
-//    In this case we need the signature of emscripten_longjmp to be (int,
-//    int). So we need two different kinds of emscripten_longjmp signatures in
-//    LLVM IR. Both signatures will be lowered to (int, int) eventually, but
-//    in LLVM IR, types are not lowered yet.
-//    So we declare two functions in LLVM:
-//    emscripten_longjmp_jmpbuf(jmp_buf, int)
-//    emscripten_longjmp(int, int)
-//    And we change the name of emscripten_longjmp_jmpbuf to
-//    emscripten_longjmp here.
-// 2. Converts invoke wrapper names.
-//    Refer to the comments in fixEmExceptionInvoke below.
-struct FixInvokeFunctionNamesWalker
-  : public PostWalker<FixInvokeFunctionNamesWalker> {
-  Module& wasm;
-  std::vector<Name> toRemove;
-  std::map<Name, Name> importRenames;
-  std::map<Name, Name> functionRenames;
-  std::set<Signature> invokeSigs;
-  ImportInfo imports;
-
-  FixInvokeFunctionNamesWalker(Module& _wasm) : wasm(_wasm), imports(wasm) {}
-
-  // Converts invoke wrapper names generated by LLVM backend to real invoke
-  // wrapper names that are expected by JavaScript glue code.
-  // This is required to support wasm exception handling (asm.js style).
-  //
-  // LLVM backend lowers
-  //   invoke @func(arg1, arg2) to label %invoke.cont unwind label %lpad
-  // into
-  // ... (some code)
-  //   call @invoke_SIG(func, arg1, arg2)
-  // ... (some code)
-  // SIG is a mangled string generated based on the LLVM IR-level function
-  // signature. In LLVM IR, types are not lowered yet, so this mangling scheme
-  // simply takes LLVM's string representtion of parameter types and concatenate
-  // them with '_'. For example, the name of an invoke wrapper for function
-  // void foo(struct mystruct*, int) will be
-  // "__invoke_void_%struct.mystruct*_int".
-  // This function converts the names of invoke wrappers based on their lowered
-  // argument types and a return type. In the example above, the resulting new
-  // wrapper name becomes "invoke_vii".
-  Name fixEmExceptionInvoke(const Name& name, Signature sig) {
-    std::string nameStr = name.c_str();
-    if (nameStr.front() == '"' && nameStr.back() == '"') {
-      nameStr = nameStr.substr(1, nameStr.size() - 2);
-    }
-    if (nameStr.find("__invoke_") != 0) {
-      return name;
-    }
-
-    std::vector<Type> newParams(sig.params.begin() + 1, sig.params.end());
-    Signature sigWoOrigFunc = Signature(Type(newParams), sig.results);
-    invokeSigs.insert(sigWoOrigFunc);
-    return Name("invoke_" +
-                getSig(sigWoOrigFunc.results, sigWoOrigFunc.params));
-  }
-
-  void visitFunction(Function* curr) {
-    if (!curr->imported()) {
-      return;
-    }
-
-    Name newname = fixEmExceptionInvoke(curr->base, curr->sig);
-    if (newname == curr->base) {
-      return;
-    }
-
-    BYN_TRACE("renaming import: " << curr->module << "." << curr->base << " ("
-                                  << curr->name << ") -> " << newname << "\n");
-
-    if (auto* f = imports.getImportedFunction(curr->module, newname)) {
-      BYN_TRACE("remove redundant import: " << curr->base << "\n");
-      toRemove.push_back(curr->name);
-      // Make sure the existing import has the correct internal name.
-      if (f->name != newname) {
-        functionRenames[f->name] = newname;
-      }
-    } else {
-      BYN_TRACE("rename import: " << curr->base << "\n");
-      curr->base = newname;
-    }
-
-    functionRenames[curr->name] = newname;
-
-    // Ensure that an imported functions of this name exists.
-    importRenames[curr->base] = newname;
-  }
-
-  void visitModule(Module* curr) {
-    for (auto name : toRemove) {
-      wasm.removeFunction(name);
-    }
-
-    // Rename all uses of the old function to the new import name
-    ModuleUtils::renameFunctions(wasm, functionRenames);
-
-    // For imports that for renamed, update any associated GOT.func imports.
-    for (auto& pair : importRenames) {
-      BYN_TRACE("looking for: GOT.func." << pair.first << "\n");
-      if (auto g = imports.getImportedGlobal("GOT.func", pair.first)) {
-        BYN_TRACE("renaming corresponding GOT entry: " << g->base << " -> "
-                                                       << pair.second << "\n");
-        g->base = pair.second;
-      }
-    }
-  }
-};
-
-void EmscriptenGlueGenerator::fixInvokeFunctionNames() {
-  BYN_TRACE("fixInvokeFunctionNames\n");
-  FixInvokeFunctionNamesWalker walker(wasm);
-  walker.walkModule(&wasm);
-}
-
 void printSignatures(std::ostream& o, const std::set<Signature>& c) {
   o << "[";
   bool first = true;
@@ -746,7 +618,7 @@ std::string EmscriptenGlueGenerator::generateEmscriptenMetadata(
   meta << "  \"invokeFuncs\": [";
   commaFirst = true;
   ModuleUtils::iterImportedFunctions(wasm, [&](Function* import) {
-    if (import->base.startsWith("invoke_")) {
+    if (import->module == ENV && import->base.startsWith("invoke_")) {
       if (invokeFuncs.insert(import->base.str).second) {
         meta << nextElement() << '"' << import->base.str << '"';
       }

test/passes/post-emscripten.txt

@@ -176,16 +176,3 @@
   )
  )
 )
-(module
- (type $i32_i32_=>_none (func (param i32 i32)))
- (import "env" "emscripten_longjmp" (func $a (param i32 i32)))
- (import "env" "emscripten_longjmp" (func $b (param i32 i32)))
-)
-(module
- (type $i32_i32_=>_none (func (param i32 i32)))
- (import "env" "emscripten_longjmp_jmpbuf" (func $b (param i32 i32)))
-)
-(module
- (type $i32_i32_=>_none (func (param i32 i32)))
- (import "env" "emscripten_longjmp" (func $a (param i32 i32)))
-)

test/passes/post-emscripten.wast

@@ -148,14 +148,3 @@
    )
   )
 )
-;; longjmp renaming
-(module
-  (import "env" "emscripten_longjmp" (func $a (param i32 i32)))
-  (import "env" "emscripten_longjmp_jmpbuf" (func $b (param i32 i32)))
-)
-(module
-  (import "env" "emscripten_longjmp_jmpbuf" (func $b (param i32 i32)))
-)
-(module
-  (import "env" "emscripten_longjmp" (func $a (param i32 i32)))
-)