[cfe-dev] Proposal: Type-Aware Memory Profiling

[Dai Mikurube]

Thanks for your interest.

Does "the context information" mean like a call site (__FILE__ and
__LINE__)?  If so, yes, preserving them may be useful.  It might be a good
idea if it is committed to the Clang tree.  I didn't implement it in the
prototype just because I didn't use it -- we're using calling stacks
instead.


On Thu, Dec 6, 2012 at 5:24 PM, Onewastedlife <onewastedlife at gmail.com>wrote:

> Interesting.. Why would you not preserve the context information as well?
>
> Regard,
> Ramneek
>
> On Dec 6, 2012, at 11:28 PM, Dai Mikurube <dmikurube at chromium.org> wrote:
>
> Hi cfe-dev,
>
> I'd like to propose a way of Type-Aware Memory Profiling 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.
> * http://llvm.org/devmtg/2012-11/Weber_TypeAwareMemoryProfiling.pdf
> * http://llvm.org/devmtg/2012-11/videos/Weber_TypeAwareMemoryProfiling.mp4
>
> 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.
>
>
> What do you think?  I wonder if I could have your opinions about it.  The
> details are discussed in this document.
> https://docs.google.com/document/d/1zyJ3FJhheJ5iSxYaMXARkZcR61tx6r44euMJbWw8jFY/edit
>
> 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.
>
>
> An example follows :
>
> $ cat typeaware.cc
> #include <stdio.h>
> #include <typeinfo>
>
> struct Klass {
>   int x, y, z;
> };
>
> void* __op_new_intercept__(
>     void* address, std::size_t size, const std::type_info& type) {
>   printf("Allocated %lu bytes for %s at %016p.\n",
>          size, type.name(), address);
>   return address;
> }
>
> void* __op_delete_intercept__(
>     void* address, std::size_t size, const std::type_info& type) {
>   printf("Deallocated %lu bytes for %s at %016p.\n",
>          size, type.name(), address);
>   return address;
> }
>
> int main() {
>   int *i;
>   Klass *k;
>   i = new int(3);
>   k = new Klass();
>   delete k;
>   delete i;
>   return 0;
> }
>
> $ clang++ -fintercept-allocation-functions typeaware.cc
>
> $ ./a.out
> Allocated 4 bytes for i at 0x000000022df010.
> Allocated 12 bytes for 5Klass at 0x000000022df030.
> Deallocated 12 bytes for 5Klass at 0x000000022df030.
> Deallocated 4 bytes for i at 0x000000022df010.
>
> --
> Dai MIKURUBE
>    dmikurube at chromium.org
>
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> cfe-dev at cs.uiuc.edu
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>
>


-- 
Dai MIKURUBE
   dmikurube at chromium.org
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