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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 - Warning: index register overlaps transfer register after 60e0120c913dd"
href="https://bugs.llvm.org/show_bug.cgi?id=44828">44828</a>
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<th>Summary</th>
<td>Warning: index register overlaps transfer register after 60e0120c913dd
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>Other
</td>
</tr>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: ARM
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>natechancellor@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, peter.smith@linaro.org, Ties.Stuij@arm.com
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<p>
<div>
<pre>When building an ARM Linux kernel, we see assembler warnings after
60e0120c913dd1d4bfe33769e1f000a076249a42.
$ make -j$(nproc) -s ARCH=arm CC=clang CROSS_COMPILE=arm-linux-gnueabi-
O=out.arm32 distclean defconfig kernel/sched/fair.o
/tmp/fair-f01157.s: Assembler messages:
/tmp/fair-f01157.s:1048: Warning: index register overlaps transfer register
I was able to creduce a problematic translation unit to
struct g {
long h;
struct g *i;
struct g *j
};
struct k {
struct k *b
};
struct l {
long m;
int n
};
struct o {
} __attribute__((__aligned__(1 << 6)));
struct a {
struct a *b, *c
} aj(ak) {
*(volatile long long *)ak;
}
struct p {
struct l a;
long q;
struct g r;
struct a s;
int t;
long long u;
long v;
long long b;
long w;
struct o aa
};
struct {
long d;
void *e;
int f;
int b;
int c;
struct k x;
int y;
int z;
long ab;
int ac;
int a;
int ad;
int t;
int ae;
int af;
int ag;
int ah;
struct p ai
} a;
al() { aj(&a.ai.aa); }
See <a href="https://github.com/ClangBuiltLinux/linux/issues/838">https://github.com/ClangBuiltLinux/linux/issues/838</a> for more details.
This is going to be a regression in clang-10, it would be nice to either revert
that commit or come up with a fix quickly, since this was reported on
Phabricator three weeks ago and there has been no movement.</pre>
</div>
</p>
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