1 files changed, 50 insertions, 9 deletions

diff --git a/src/s2wasm.h b/src/s2wasm.h
index a45f3aab4..a23cbb549 100644
--- a/src/s2wasm.h
+++ b/src/s2wasm.h
@@ -248,7 +248,8 @@ class S2WasmBuilder {
         s++;
         offset = -getInt();
       }
-      linkerObj->addRelocation(kind, target, cleanFunction(name), offset);
+      linkerObj->addRelocation(kind, target,
+                               fixEmLongjmp(cleanFunction(name)), offset);
       return true;
     }
   }
@@ -566,7 +567,7 @@ class S2WasmBuilder {
     decl->name = "FUNCSIG$" + sig;
 
     FunctionType *ty = wasm->checkFunctionType(decl->name);
-    Name name = fixEmExceptionInvoke(rawName, sig);
+    Name name = fixEmEHSjLjNames(rawName, sig);
     if (!ty) {
       // The wasm module takes ownership of the FunctionType if we insert it.
       // Otherwise it's already in the module and ours is freed.
@@ -891,7 +892,7 @@ class S2WasmBuilder {
           }
         }
         Name target = linkerObj->resolveAlias(
-            fixEmExceptionInvoke(rawTarget, curr->type, curr->operands),
+            fixEmEHSjLjNames(rawTarget, curr->type, curr->operands),
             LinkerObject::Relocation::kFunction);
         curr->target = target;
         if (!linkerObj->isFunctionImplemented(target)) {
@@ -1347,6 +1348,52 @@ class S2WasmBuilder {
     }
   }
 
+  // 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.
+  template<typename ListType>
+  Name fixEmEHSjLjNames(const Name &name, WasmType result,
+                        const ListType &operands) {
+    return fixEmEHSjLjNames(name, getSig(result, operands));
+  }
+
+  Name fixEmEHSjLjNames(const Name &name, const std::string &sig) {
+    if (name == "emscripten_longjmp_jmpbuf")
+      return "emscripten_longjmp";
+    return fixEmExceptionInvoke(name, sig);
+  }
+
+  // This version only converts emscripten_longjmp_jmpbuf and does not deal
+  // with invoke wrappers. This is used when we only have a function name as
+  // relocatable constant.
+  Name fixEmLongjmp(const Name &name) {
+    if (name == "emscripten_longjmp_jmpbuf")
+      return "emscripten_longjmp";
+    return name;
+  }
+
   // 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).
@@ -1366,12 +1413,6 @@ class S2WasmBuilder {
   // 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".
-  template<typename ListType>
-  Name fixEmExceptionInvoke(const Name &name, WasmType result,
-                        const ListType &operands) {
-    return fixEmExceptionInvoke(name, getSig(result, operands));
-  }
-
   Name fixEmExceptionInvoke(const Name &name, const std::string &sig) {
     std::string nameStr = name.c_str();
     if (nameStr.front() == '"' && nameStr.back() == '"') {