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<p class="MsoNormal">Hello all,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">First, apologizes if this is the wrong mailing list for this discussion.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am using the TI 18.1.5 compiler to compile for the TM4C1294NCPDT chip. A longer/better explanation of my problems might be obtained from the TI forums of my issue, which didn’t gain traction:
<a href="https://e2e.ti.com/support/tools/ccs/f/81/t/787948">https://e2e.ti.com/support/tools/ccs/f/81/t/787948</a><o:p></o:p></p>
<p class="MsoNormal">So I am trying to go upstream for more discussion.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Summary of my problem: Using deque::push_back on structures over 64 bytes will cause a crash.<o:p></o:p></p>
<p class="MsoNormal">Example code:<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555">#include <deque>
</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555">struct</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#555555">s {
</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555"> char</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#555555">d[65];
</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555">};
</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555">int</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#555555">main()
</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555">{
</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555"> int</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#555555">size = sizeof(s);
</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555">
</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555"> std::deque<s> test;
</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555"> test.push_back(s());
</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555"> test.push_back(s()); // will crash here
</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555"> while</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555">
</span><span style="font-size:10.0pt;font-family:"Courier New";color:#555555">(1){}
</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New";color:#555555">}</span><span style="font-size:10.5pt;font-family:Consolas;color:#555555"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Digging in to the problem more, I found that if I call resize(1) first, push_back will work just fine thereafter. I found there are differences between __add_back_capacity() vs __add_back_capacity(1). Should there be?<o:p></o:p></p>
<p class="MsoNormal">Example, look at comments for output result:<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">#define protected public<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">#define private public<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">#include <deque><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">struct s {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> char d[65];<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">};<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">int main()<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">{<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> std::deque<s> test;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> test.resize(1, s());<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> int back_spare = test.__back_spare(); // 0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> int cap = test.__capacity(); // 1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> std::deque<s> test;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> test.push_back(s());<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> int back_spare = test.__back_spare(); // -1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> int cap = test.__capacity(); // 0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> std::deque<s> test;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> test.__add_back_capacity(1);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> int back_spare = test.__back_spare(); // 1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> int cap = test.__capacity(); // 1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> std::deque<s> test;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> test.__add_back_capacity();<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> int back_spare = test.__back_spare(); // 0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> int cap = test.__capacity(); // 0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> while (1){}<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">}<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">TI’s implementation of the struct __deque_block_size allows a minimum size of 1. Not sure if this should cause a problem or not.<o:p></o:p></p>
<p class="MsoNormal">TI:<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">template <class _ValueType, class _DiffType><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">struct __deque_block_size {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> enum __attribute__((__packed__)) { _MAX_BYTES = 32 * sizeof(void*) };<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New""> static const _DiffType value = sizeof(_ValueType) < _MAX_BYTES ? (_MAX_BYTES / sizeof(_ValueType)) : 1;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Courier New"">};<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">So, is this a problem in LLVM’s __add_back_capacity() or TI’s block_size?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Jason<o:p></o:p></p>
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