Safari iOS 14.3 fails to load wasm even with -sMIN_SAFARI_VERSION=120000

[ricardperez]

Please include the following in your bug report:

Version of emscripten/emsdk:
3.1.26
I tested and verified that things work as expected in 3.1.25.

Please include the output emcc -v here

emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.26 (8eaf19f1c6a9a1b0cd0f9a91657366829e34ae5c)
clang version 16.0.0 (https://github.com/llvm/llvm-project f81f0cb75a2808a67d2662f044ad07628fc9d900)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/bin

Failing command line in full:
N/A

Full link command and output with -v appended:
Even for runtime issues it helps a lot if you can include the full link command.
Adding -v to the link command will show all of the sub-commands run which
can help us diagnose your issue.

This is the output of both build and link as I do it all in a single step:

 "/Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/bin/clang" --version
 "/Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/bin/clang++" -target wasm32-unknown-emscripten -fignore-exceptions -fvisibility=default -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -DEMSCRIPTEN -I/Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/include/SDL --sysroot=/Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot -Xclang -iwithsysroot/include/compat -O2 -v lib.cpp -c -o /var/folders/nw/669_3plx2jl5sts50b2x101r0000gn/T/emscripten_temp_g2dafa7q/lib_0.o
clang version 16.0.0 (https://github.com/llvm/llvm-project f81f0cb75a2808a67d2662f044ad07628fc9d900)
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/bin
 (in-process)
 "/Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/bin/clang-16" -cc1 -triple wasm32-unknown-emscripten -emit-obj --mrelax-relocations -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name lib.cpp -mrelocation-model static -mframe-pointer=none -ffp-contract=on -fno-rounding-math -mconstructor-aliases -target-cpu generic -mllvm -treat-scalable-fixed-error-as-warning -debugger-tuning=gdb -v -fcoverage-compilation-dir=/Users/ricardperez/gitlab/ricard/hello-webassembly -resource-dir /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/lib/clang/16 -D EMSCRIPTEN -I /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/include/SDL -isysroot /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot -internal-isystem /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/include/wasm32-emscripten/c++/v1 -internal-isystem /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1 -internal-isystem /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/lib/clang/16/include -internal-isystem /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/include/wasm32-emscripten -internal-isystem /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/include -O2 -fdeprecated-macro -fdebug-compilation-dir=/Users/ricardperez/gitlab/ricard/hello-webassembly -ferror-limit 19 -fvisibility=default -fgnuc-version=4.2.1 -fcxx-exceptions -fignore-exceptions -fexceptions -fcolor-diagnostics -vectorize-loops -vectorize-slp -iwithsysroot/include/compat -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr -o /var/folders/nw/669_3plx2jl5sts50b2x101r0000gn/T/emscripten_temp_g2dafa7q/lib_0.o -x c++ lib.cpp
clang -cc1 version 16.0.0 based upon LLVM 16.0.0git default target x86_64-apple-darwin22.5.0
ignoring nonexistent directory "/Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/include/wasm32-emscripten/c++/v1"
ignoring nonexistent directory "/Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/include/wasm32-emscripten"
#include "..." search starts here:
#include <...> search starts here:
 /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/include/SDL
 /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/include/compat
 /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1
 /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/lib/clang/16/include
 /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/include
End of search list.
 "/Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/bin/wasm-ld" -o lib.wasm /var/folders/nw/669_3plx2jl5sts50b2x101r0000gn/T/emscripten_temp_g2dafa7q/lib_0.o -L/Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten -lGL -lal -lhtml5 -lstubs -lnoexit -lc -ldlmalloc -lcompiler_rt -lc++-noexcept -lc++abi-noexcept -lsockets -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --import-undefined --strip-debug --export-if-defined=main --export-if-defined=__start_em_asm --export-if-defined=__stop_em_asm --export-if-defined=__start_em_lib_deps --export-if-defined=__stop_em_lib_deps --export-if-defined=__start_em_js --export-if-defined=__stop_em_js --export-if-defined=__main_argc_argv --export=stackSave --export=stackRestore --export=stackAlloc --export=__wasm_call_ctors --export=__errno_location --export=__get_temp_ret --export=__set_temp_ret --export=malloc --export=__cxa_is_pointer_type --export-table -z stack-size=5242880 --initial-memory=16777216 --no-entry --max-memory=2147483648 --global-base=1024
 "/Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/bin/wasm-emscripten-finalize" --dyncalls-i64 --pass-arg=legalize-js-interface-exported-helpers lib.wasm -o lib.wasm --detect-features
 "/Users/ricardperez/gitlab/emscripten-core/emsdk/node/15.14.0_64bit/bin/node" /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/src/compiler.js /var/folders/nw/669_3plx2jl5sts50b2x101r0000gn/T/tmpxbial42l.json
 "/Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/bin/wasm-opt" --strip-dwarf --signext-lowering --post-emscripten -O2 --low-memory-unused --zero-filled-memory --pass-arg=directize-initial-contents-immutable --strip-debug --strip-producers lib.wasm -o lib.wasm --mvp-features --enable-mutable-globals --enable-sign-ext
 "/Users/ricardperez/gitlab/emscripten-core/emsdk/node/15.14.0_64bit/bin/node" /Users/ricardperez/gitlab/emscripten-core/emsdk/upstream/emscripten/tools/acorn-optimizer.js /var/folders/nw/669_3plx2jl5sts50b2x101r0000gn/T/emscripten_temp_g2dafa7q/lib.js JSDCE minifyWhitespace -o /var/folders/nw/669_3plx2jl5sts50b2x101r0000gn/T/emscripten_temp_g2dafa7q/lib.jso1.js

The issue

I have discovered that my application is not working on iOS 14.3 (and lower) - and it should.

This is the error I am seeing:

The issue started to happen when the emscripten toolchain was bumped from version 3.1.23 to 3.1.34. I have done different builds with different Emscripten versions and this only happens starting at 3.1.26. Checking the release notes in the changelog I see this:

• Inline with the recent changes to llvm and binaryen, emscripten will now, by default, enable the sign-extension and mutable-globals WebAssembly proposals. In order to do so the default minimum safari version (MIN_SAFARI_VERSION) was updated from 12.0 to 14.1, and support for the old EdgeHTML engine (MIN_EDGE_VERSION) was removed by default. If you want to continue to support these older engines you can use these settings (-sMIN_SAFARI_VERSION=120000 and/or -sMIN_EDGE_VERSION=44) to revert to the previous defaults, which will result in the new proposals being disabled. Note that in order to avoid support for the sign-extension emscripten uses a binaryen pass, so targeting older browsers requires the running of wasm-opt and is therefore incompatible with ERROR_ON_WASM_CHANGES_AFTER_LINK (i.e. fast linking). (Bump min browser versions such they all support llvm default features #17690)

This explicitly says that iOS min version was changed from 12.0.0 to 14.1. I am testing with iOS 14.3, so in theory I should not be affected by this. But anyway I tried to link with the recommended flag -sMIN_SAFARI_VERSION=120000. It didn't help. See the next section.

Reproduction sample

I managed to create a sample project to reproduce the problem.

It helped me to discover that the optimisation flags make a difference to the result. Using none or little optmisiations (-O0 & -O1) it will work fine when I also use -s MIN_SAFARI_VERSION=120000. But bigger optimisations (-O2 and more) will always fail with the error no matter if MIN_SAFARI_VERSION was set or not.

This is the project setup I am using:

index.html

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>WebAssembly using Emscripten</title>
</head>
<body style="background-color:#1D1E20; color:wheat">
    <h1>Test</h1>
    <script>
        const worker = new Worker('worker.js');
    </script>
</body>
</html>

worker.js

importScripts('lib.js');

lib.cpp

#include <iostream>

int main() {
    std::cout << "Hello from c++" << std::endl;
    return 0;
}

And this is the build script:

source "/Users/ricardperez/gitlab/emscripten-core/emsdk/emsdk_env.sh" &> /dev/null

emsdk install 3.1.26
emsdk activate 3.1.26

em++ lib.cpp -o lib.js -O2 -sMIN_SAFARI_VERSION=120000
# note that using -O1 makes it work as expected
# emrun index.html

Any clue of what might be causing the problem?

[ricardperez]

Using -g3 I get a similar error:

failed to asynchronously prepare wasm: CompileError: WebAssembly.Module doesn't parse at byte 164: invalid opcode 192, in function at index 2

When I run wasm-objdump -x ~/sample-project/lib.wasm I see this in the output:

 - func[2] sig=0 <emscripten_resize_heap> <- env.emscripten_resize_heap

[ricardperez]

I started testing with newer emscripten versions than 3.1.34. I installed 3.1.40 and it did work as expected, no error when -sMIN_SAFARI_VERSION=120000 is provided.

I did some tests, and the first version that gave me expected results is 3.1.37. I couldn't find anything in the changelog talking about any related fix.

Tomorrow I will try my real project with such version and see.

[sbc100]

I believe this was fixed in binaryen: WebAssembly/binaryen#5676

The original bug was #19121, and I guess this a duplicate of that one?

[ricardperez]

Alright, thanks @sbc100.

Shall the release notes for 3.1.37 be updated to reflect such fix maybe? This would made my life easier to identify the problem I guess.

[eatsjobs]

Compiling with emsdk v3.1.23 here is the resulting not working code

On Safari 14.3 there's also another problem: WebGLRederingContext is not available in Worker scope and this code fails at line 7

createContext: function (canvas, webGLContextAttributes) {
    if (!canvas.getContextSafariWebGL2Fixed) {
      canvas.getContextSafariWebGL2Fixed = canvas.getContext;
      function fixedGetContext(ver, attrs) {        
        var gl = canvas.getContextSafariWebGL2Fixed(ver, attrs);
        // WebGLRenderingContext is not available in scope. this will throw an error
        return ver == "webgl" == gl instanceof WebGLRenderingContext ? gl : null;
      }
      canvas.getContext = fixedGetContext;
    }
    var ctx = canvas.getContext("webgl", webGLContextAttributes);
    if (!ctx) return 0;
    var handle = GL.registerContext(ctx, webGLContextAttributes);
    return handle;
  },

while this works correctly

createContext: function (canvas, webGLContextAttributes) {
    if (!canvas.getContextSafariWebGL2Fixed) {
      canvas.getContextSafariWebGL2Fixed = canvas.getContext;
      function fixedGetContext(ver, attrs) {
        try { 
          var gl = canvas.getContextSafariWebGL2Fixed(ver, attrs);
          // WebGLRenderingContext is not available in scope. but the error will be handled
          return ver == "webgl" == gl instanceof WebGLRenderingContext ? gl : null;
       } catch(e) {
          return null;
       }        
      }
      canvas.getContext = fixedGetContext;
    }
    var ctx = canvas.getContext("webgl", webGLContextAttributes);
    if (!ctx) return 0;
    var handle = GL.registerContext(ctx, webGLContextAttributes);
    return handle;
  },