Stop renaming longjmp in wasm-emscripten-finalize (#3111)

Instead of finalize renaming emscripten_longjmp_jmpbuf to emscripten_longjmp,
do nothing in finalize. But in the optional --post-emscripten pass, rename it there if
both exist, so that we don't end up using two imports (other optimization passes
can then remove an unneeded import).

Depends on emscripten-core/emscripten#12157 to land first so that emscripten
can handle both names, and it is just an optimization to have one or the other.

See https://github.com/WebAssembly/binaryen/issues/3043

1 files changed, 18 insertions, 0 deletions

diff --git a/src/passes/PostEmscripten.cpp b/src/passes/PostEmscripten.cpp
index 2397284c3..aa6c90977 100644
--- a/src/passes/PostEmscripten.cpp
+++ b/src/passes/PostEmscripten.cpp
@@ -130,6 +130,9 @@ struct PostEmscripten : public Pass {
       }
     }
 
+    // Optimize imports
+    optimizeImports(runner, module);
+
     // Optimize calls
     OptimizeCalls().run(runner, module);
 
@@ -137,6 +140,21 @@ struct PostEmscripten : public Pass {
     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