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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - inline assembly and =g constraint on output argument"
href="http://llvm.org/bugs/show_bug.cgi?id=15765">15765</a>
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<th>Summary</th>
<td>inline assembly and =g constraint on output argument
</td>
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<th>Product</th>
<td>new-bugs
</td>
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<th>Version</th>
<td>3.2
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>new bugs
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>bruce.mitchener@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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</tr>
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<th>Classification</th>
<td>Unclassified
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</tr></table>
<p>
<div>
<pre>In emscripten, we support having JS as "inline assembly" (it makes perfect
sense in context).
With a very simple program:
double get() {
double ret = 0;
__asm __volatile__("12/3.3":"=r"(ret));
return ret;
}
int main() {
return (int)get();
}
And compiling it:
/usr/local/bin/clang -target i386-pc-linux-gnu -emit-llvm -S -o m-r.ll
test.c
the inline asm compiles to:
%0 = call double asm sideeffect "12/3.3",
"=r,~{dirflag},~{fpsr},~{flags}"() nounwind, !srcloc !0
However, changing it to a =g constraint instead of =r results in this:
call void asm sideeffect "12/3.3",
"=*imr,~{dirflag},~{fpsr},~{flags}"(double* %ret) nounwind, !srcloc !0
This shows that it isn't picking up the value into ret.
Is =g permissible here or must I use =r?</pre>
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