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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW " title="NEW --- - __attribute__((naked)) broken for possibly-returning functions" href="https://urldefense.proofpoint.com/v2/url?u=https-3A__llvm.org_bugs_show-5Fbug.cgi-3Fid-3D23971&d=AwMBaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=pF93YEPyB-J_PERP4DUZOJDzFVX5ZQ57vQk33wu0vio&m=DL6G9N5_NSxED_vMH0OksI3KObXJGunfwf4akOGHWv4&s=MSVg7_22p_aojl0S634sQZq2rNuCXcxu9sEIqo3GE2w&e=">23971</a>
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<th>Summary</th>
<td>__attribute__((naked)) broken for possibly-returning functions
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</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
</td>
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<th>Component</th>
<td>LLVM Codegen
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>eugeni.stepanov@gmail.com
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Naked functions get unreachable statement at the end, which may be propagated
into their callers.
# cat 1.c
__attribute__((naked,noinline)) void f() {
asm volatile("bx lr\n\t");
}
int g() {
f();
return 42;
}
# clang -c 1.c -S -emit-llvm -o - -O1
define void @f() #0 {
entry:
tail call void asm sideeffect "bx lr\0A\09", "~{dirflag},~{fpsr},~{flags}"()
#2, !srcloc !1
unreachable
}
; Function Attrs: noreturn nounwind uwtable
define i32 @g() #1 {
entry:
tail call void @f()
unreachable
}
"return 42" in g() is gone.</pre>
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