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<base href="http://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - missed optimization: unused std::string"
href="http://llvm.org/bugs/show_bug.cgi?id=17151">17151</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>missed optimization: unused std::string
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</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>C++
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>ruslan_baratov@yahoo.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre><span class="quote">>cat test.cpp</span >
#include <string>
void foo() {
std::string a = "abc";
}
void boo() {
}
Expected, that both 'foo' and 'boo' produce same asm, but it's not:
<span class="quote">>clang++ -O3 -stdlib=libc++ -save-temps -O3 -c -fomit-frame-pointer test.cpp
>cat test.s</span >
__Z3foov: ## @_Z3foov
pushq %rbx
subq $32, %rsp
leaq 8(%rsp), %rbx
leaq L_.str(%rip), %rsi
movq %rbx, %rdi
movl $3, %edx
callq
__ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEE6__initEPKcm
movq %rbx, %rdi
callq
__ZNSt3__112basic_stringIcNS_11char_traitsIcEENS_9allocatorIcEEED1Ev
addq $32, %rsp
popq %rbx
ret
__Z3boov: ## @_Z3boov
ret</pre>
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