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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 --- - Constructing a vector with an initializer list generates more code than push_back / emplace_back"
href="https://llvm.org/bugs/show_bug.cgi?id=30317">30317</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Constructing a vector with an initializer list generates more code than push_back / emplace_back
</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>Windows NT
</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>LLVM Codegen
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>dcheng@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Simple test case:
#include <stdio.h>
#include <string>
#include <vector>
void PrintVector(const std::vector<std::string>& strings) {
for (const auto& s : strings) {
printf("%s\n", s.data());
}
}
void Foo() {
std::vector<std::string> names;
names.push_back("abc");
names.push_back("def");
names.push_back("ghi");
PrintVector(names);
}
void Bar() {
std::vector<std::string> names{
"abc",
"def",
"ghi",
};
PrintVector(names);
}
int main() {
Foo();
Bar();
}
With -O2, the function sizes are roughly the same. Foo() is 847 bytes, Bar() is
844 bytes.
With -O1, Foo() is much smaller at 294 bytes, while Bar() is 396 bytes.</pre>
</div>
</p>
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