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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - stack-protector-strong: Bad machine code: Using an undefined physical register"
href="https://bugs.llvm.org/show_bug.cgi?id=41417">41417</a>
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<th>Summary</th>
<td>stack-protector-strong: Bad machine code: Using an undefined physical register
</td>
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<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>Other
</td>
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<th>OS</th>
<td>FreeBSD
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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
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>dimitry@andric.com
</td>
</tr>
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
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<div>
<pre>As reported in <a href="https://bugs.freebsd.org/237074">https://bugs.freebsd.org/237074</a>, the multimedia/vlc3 port fails
to build for armv6 with a fatal backend error:
[... lots of stuff ... ]
*** Bad machine code: Using an undefined physical register ***
- function: AVI_ChunkRead
- basic block: %bb.11 if.then13 (0x804066b68)
- instruction: TCRETURNri %22:tcgpr, implicit $sp, implicit $r0, implicit
killed $r1
- operand 2: implicit $r0
*** Bad machine code: Using an undefined physical register ***
- function: AVI_ChunkRead
- basic block: %bb.11 if.then13 (0x804066b68)
- instruction: TCRETURNri %22:tcgpr, implicit $sp, implicit $r0, implicit
killed $r1
- operand 3: implicit killed $r1
fatal error: error in backend: Found 2 machine code errors.
Minimized test case:
// clang -cc1 -triple armv6kz---gnueabihf -S -target-cpu arm1176jzf-s -O2
-stack-protector 2 libavi-min.c
void c(_Bool *);
void a() {
_Bool b;
c(&b);
}
const struct {
int d;
int (*e)();
} f[] = {};
int h(void);
int AVI_ChunkRead_p_chk() {
int g = h();
if (g)
return f[g].e(0, 0);
a();
return 0;
}
Using -stack-protector 1, or lowering the optimization level to -O1 makes it
work again.
Also, if you add (int, int) to the 'e' member of the struct, like so:
const struct {
int d;
int (*e)(int, int);
} f[] = {};
it works. So maybe this is related to C varargs functions.</pre>
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