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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 - Missed opportunity to use tail calls"
href="https://bugs.llvm.org/show_bug.cgi?id=50117">50117</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Missed opportunity to use tail calls
</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>
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<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>
<tr>
<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>david.bolvansky@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>void foo (char *, int n);
int bar (int);
int baz (char *p);
int
test1 (int n)
{
{
char buf[64];
foo (buf, n);
}
return bar (n);
}
void
test2 (char *p)
{
{
char c;
baz (&c);
}
baz (p);
}
test1: # @test1
push rbx
sub rsp, 64
mov ebx, edi
mov rdi, rsp
mov esi, ebx
call foo
mov edi, ebx
call bar // can be jmp bar
add rsp, 64
pop rbx
ret
test2: # @test2
push rbx
sub rsp, 16
mov rbx, rdi
lea rdi, [rsp + 15]
call baz
mov rdi, rbx
call baz // can be jmp baz
add rsp, 16
pop rbx
ret
<a href="https://godbolt.org/z/TvM81eYod">https://godbolt.org/z/TvM81eYod</a>
In IR I see that we have just call, not "tail call", so a middle-end issue.</pre>
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