Document some emsdk patches (pyodide#863)

joemarshall · Jan 3, 2021 · 6391a75 · 6391a75
1 parent 42c53ac
commit 6391a75
Showing 1 changed file with 19 additions and 0 deletions.
diff --git a/emsdk/patches/emulate_pointer.patch b/emsdk/patches/emulate_pointer.patch
@@ -0,0 +1,19 @@
+This fixes an upstream bug introduced in emscripten 1.38.34 that causes dlsym
+to always return 0 for function pointers when EMULATE_FUNCTION_POINTER_CASTS is
+enabled. This is a simple typo, since `mangled == "_" + symbol`. This piece of
+code is no longer present in upstream master, hence there is no effort to
+upstream the fix.
+
+diff --git a/emsdk/fastcomp/emscripten/src/library.js b/emsdk/fastcomp/emscripten/src/library.js
+index 97cca10..5c002d7 100644
+--- a/emsdk/fastcomp/emscripten/src/library.js
++++ b/emsdk/fastcomp/emscripten/src/library.js
+@@ -2194,7 +2194,7 @@ LibraryManager.library = {
+     // can call (which does not use that ABI), as the function pointer would
+     // not be usable from wasm. instead, the wasm has exported function pointers
+     // for everything we need, with prefix fp$, use those
+-    result = lib.module['fp$' + symbol];
++    result = lib.module['fp$' + mangled];
+     if (typeof result === 'object') {
+       // a breaking change in the wasm spec, globals are now objects
+       // https://github.com/WebAssembly/mutable-global/issues/1