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<base href="https://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - llvm/clang doesn't inline __builtin_mempcpy"
href="https://llvm.org/bugs/show_bug.cgi?id=26903">26903</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>llvm/clang doesn't inline __builtin_mempcpy
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>new bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>hjl.tools@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>david.l.kreitzer@intel.com, llvm-bugs@lists.llvm.org, zia.ansari@intel.com
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>[hjl@gnu-6 pr70155a]$ cat m.i
extern char *src, *dst;
char *
foo1 (void)
{
return __builtin_memcpy (dst, src, 16);
}
char *
foo2 (void)
{
return __builtin_mempcpy (dst, src, 16);
}
[hjl@gnu-6 pr70155a]$
/export/build/gnu/llvm-clang-bootstrap/stage1/build-x86_64-linux/bin/clang -S
-O2 m.i
[hjl@gnu-6 pr70155a]$ cat m.s
.text
.file "m.i"
.globl foo1
.p2align 4, 0x90
.type foo1,@function
foo1: # @foo1
.cfi_startproc
# BB#0:
movq dst(%rip), %rax
movq src(%rip), %rcx
movups (%rcx), %xmm0
movups %xmm0, (%rax)
retq
.Lfunc_end0:
.size foo1, .Lfunc_end0-foo1
.cfi_endproc
.globl foo2
.p2align 4, 0x90
.type foo2,@function
foo2: # @foo2
.cfi_startproc
# BB#0:
movq dst(%rip), %rdi
movq src(%rip), %rsi
movl $16, %edx
jmp mempcpy # TAILCALL
.Lfunc_end1:
.size foo2, .Lfunc_end1-foo2
.cfi_endproc
.ident "clang version 3.9.0 (<a href="http://llvm.org/git/clang.git">http://llvm.org/git/clang.git</a>
fdef93f7bb7594c6a2a623835f9d5330184bf37c) (<a href="http://llvm.org/git/llvm.git">http://llvm.org/git/llvm.git</a>
ffadaf5667befa7f105aa48fca597d26d8c7ee49)"
.section ".note.GNU-stack","",@progbits
[hjl@gnu-6 pr70155a]$
I was expecting something like
foo2:
movq dst(%rip), %rax
movq src(%rip), %rcx
movups (%rcx), %xmm0
movups %xmm0, (%rax)
addq $16, %rax
retq</pre>
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