[llvm-bugs] [Bug 47413] New: Invalid wasm with -fwasm-exceptions

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=47413

            Bug ID: 47413
           Summary: Invalid wasm with -fwasm-exceptions
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: WebAssembly
          Assignee: unassignedbugs at nondot.org
          Reporter: alonzakai at gmail.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 23924
  --> https://bugs.llvm.org/attachment.cgi?id=23924&action=edit
wasm file from LLVM

Testcase (from wasm0.test_exceptions_3):

===
#include <iostream>

int main(int argc, char **argv)
{
  int arg = argv[1][0] - '0';
  try {
    if (arg == 2) throw std::runtime_error("Hello");
  } catch(const char * ex) {
    std::cout << "Caught C string: " << ex << std::endl;
  } catch(...) {
  }

  std::cout << "Done.\n";
}
===

The output from LLVM is incorrect, but after binaryen processing it becomes
valid somehow (I think this is why this wasn't noticed earlier - removing the
binaryen processing locally uncovered it). To see the LLVM output, can build
with

EMCC_DEBUG=1 emcc test.cpp -fwasm-exceptions

and then look at /tmp/emscripten_temp/emcc-0-base.wasm (also attached). That
file looks invalid, v8 says

Compiling function #420 failed: not enough arguments on the stack for catch,
expected 1 more @+62235

and wabt says

emcc-0-base.wasm:000f0b7: error: type mismatch in try block, expected [i32] but
got []
[..]

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20200903/c0f6a8d7/attachment.html>