<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Interesting.. Why would you not preserve the context information as well? <br><br>Regard,<div>Ramneek</div></div><div><br>On Dec 6, 2012, at 11:28 PM, Dai Mikurube <<a href="mailto:dmikurube@chromium.org">dmikurube@chromium.org</a>> wrote:<br><br></div><blockquote type="cite"><div><div style="font-family:arial,helvetica,sans-serif;font-size:10pt"><div dir="ltr">Hi cfe-dev,<br clear="all"><div><br></div><div style="">I'd like to propose a way of Type-Aware Memory Proļ¬ling in Clang. It was one of the lightning talks at the DevMtg by Nico Weber on behalf of me. Slides and Video were recently published.</div>
<div>* <a href="http://llvm.org/devmtg/2012-11/Weber_TypeAwareMemoryProfiling.pdf">http://llvm.org/devmtg/2012-11/Weber_TypeAwareMemoryProfiling.pdf</a></div><div style="">* <a href="http://llvm.org/devmtg/2012-11/videos/Weber_TypeAwareMemoryProfiling.mp4">http://llvm.org/devmtg/2012-11/videos/Weber_TypeAwareMemoryProfiling.mp4</a></div>
<div style=""><br></div><div style="">Object's type information is useful to profile memory usage in a process. Type info is, however, hard to use in C++ programs. Our proposal is to make it easy by compiler's help. We implemented an early prototype, and the prototype has been working in Chromium project for a couple of months.</div>
<div><br></div><div><br></div><div style="">What do you think? I wonder if I could have your opinions about it. The details are discussed in this document. <a href="https://docs.google.com/document/d/1zyJ3FJhheJ5iSxYaMXARkZcR61tx6r44euMJbWw8jFY/edit">https://docs.google.com/document/d/1zyJ3FJhheJ5iSxYaMXARkZcR61tx6r44euMJbWw8jFY/edit</a></div>
<div style=""><br></div><div style="">tl;dr, we did it by user-defined intercepting functions for operator new and delete. If a developer defines a function __op_new_intercept__ (and if a compiler option is given!), the function intercepts operator new calls.</div>
<div style=""><br></div><div style=""><br></div><div style="">An example follows :</div><div style=""><br></div><div style="">$ cat typeaware.cc</div><div style=""><div>#include <stdio.h></div><div>#include <typeinfo></div><div>
<br></div><div>struct Klass {</div><div> int x, y, z;</div><div>};</div><div><br></div><div>void* __op_new_intercept__(</div><div> void* address, std::size_t size, const std::type_info& type) {</div><div> printf("Allocated %lu bytes for %s at %016p.\n",</div>
<div> size, <a href="http://type.name">type.name</a>(), address);</div><div> return address;</div><div>}</div><div><br></div><div>void* __op_delete_intercept__(</div><div> void* address, std::size_t size, const std::type_info& type) {</div>
<div> printf("Deallocated %lu bytes for %s at %016p.\n",</div><div> size, <a href="http://type.name">type.name</a>(), address);</div><div> return address;</div><div>}</div><div><br></div><div>int main() {</div>
<div> int *i;</div><div> Klass *k;</div><div> i = new int(3);</div><div> k = new Klass();</div><div> delete k;</div><div> delete i;</div><div> return 0;</div><div>}</div><div><br></div><div>$ clang++ -fintercept-allocation-functions typeaware.cc</div>
<div><br></div><div style="">$ ./a.out</div><div style=""><div>Allocated 4 bytes for i at 0x000000022df010.</div><div>Allocated 12 bytes for 5Klass at 0x000000022df030.</div><div>Deallocated 12 bytes for 5Klass at 0x000000022df030.</div>
<div>Deallocated 4 bytes for i at 0x000000022df010.</div></div><div><br></div></div><div style="">-- <br></div><div>Dai MIKURUBE</div><div> <a href="mailto:dmikurube@chromium.org" target="_blank" class="cremed">dmikurube@chromium.org</a></div>
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