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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - crash due to incorrect ARM code generated for std::vector initialization"
href="http://llvm.org/bugs/show_bug.cgi?id=20415">20415</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>crash due to incorrect ARM code generated for std::vector initialization
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>3.4
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Macintosh
</td>
</tr>
<tr>
<th>OS</th>
<td>MacOS X
</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>itsme@xs4all.nl
</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>compile and link the code pasted below to an ios binary, make sure you call the
'tstv' function.
the program will crash when compiled with -O3
commandline used to generate the assembly listing:
clang++ -S -arch armv7s -O3 -isysroot
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.1.sdk
-o armv7s.s tstv.cpp
my compiler version:
Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
the xcode6 beta compiler ( Apple LLVM version 6.0 (clang-600.0.41.2) (based on
LLVM 3.5svn) )
shows the same problem
======= tstv.cpp
#include <vector>
extern void logmsg(const char*);
template<typename T>
struct buf : std::vector<T>
{
buf(int n) : std::vector<T>(n) { logmsg("+"); }
~buf() { logmsg("-"); }
};
void tstv()
{
buf<int> b(256);
buf<char> a(256); // <<< here will be the crash
}
======== logmsg.cpp
// this needs to be in a seperate compilation unit
void logmsg(const char*)
{
}
===========================
the generated assembly code showing the problem
Ltmp1:
@ BB#3: @ %_ZN3bufIiEC1Ei.exit
ldr r0, [sp, #8] @ <<<<<<<<<<< problem: reading uninitialized ptr
value before 'new' is stored
str r0, [sp] @ 4-byte Spill
movs r0, #2
str r0, [sp, #16]
Ltmp3:
mov.w r0, #256
blx __Znwm
Ltmp4:
@ BB#4: @
%_ZN3bufIiEC1Ei.exit..preheader_crit_edge
ldr r2, [sp] @ 4-byte Reload
movs r1, #0
str r0, [sp, #8]
mvn r0, #255
LBB0_5: @ %.preheader
@ =>This Inner Loop Header: Depth=1
cmp r2, #0
ite ne
strbne r1, [r2] @ <<<<<<<<<<< using wrong value loaded at Ltmp1
moveq r2, #0
adds r0, #1
add.w r2, r2, #1
bne LBB0_5</pre>
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