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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Invalid wasm with -fwasm-exceptions"
href="https://bugs.llvm.org/show_bug.cgi?id=47413">47413</a>
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</tr>
<tr>
<th>Summary</th>
<td>Invalid wasm with -fwasm-exceptions
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: WebAssembly
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>alonzakai@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=23924" name="attach_23924" title="wasm file from LLVM">attachment 23924</a> <a href="attachment.cgi?id=23924&action=edit" title="wasm file from LLVM">[details]</a></span>
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 []
[..]</pre>
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