Thanks David, Eric. Yes it helped.
________________________________
From: David Chapman <[email protected]>
To: sachin gupta <[email protected]>
Cc: "[email protected]"
<[email protected]>
Sent: Friday, November 18, 2011 10:31 PM
Subject: Re: [Valgrind-users] [massif]>> string on stack is shown on heap
On 11/18/2011 8:32 AM, sachin gupta wrote:
Hi All,
>
>
>I have a simple program
>
>
>/*************************/
>
>#include <iostream>
>#include <string>
>main()
>{
>std::string test;
>test ="abc";
>
>std::string *test2 = new std::string("abc");
>delete test2;
>}
>/******************************************/
>
>
>Now I am running valgrind over it
>
>
>valgrind --tool=massif ./a.out
>
>
>
>on ms_print
>
>
>it is howing output as
>/****************************************
>
>
> n time(i) total(B) useful-heap(B) extra-heap(B) stacks(B)
>--------------------------------------------------------------------------------
> 0 0 0 0 0 0
> 1 1,385,421 40 28 12 0
> 2 1,388,597 64 36 28 0
> 3 1,389,777 104 64 40 0
> 4 1,393,400 104 64 40 0
>61.54% (64B) (heap allocation functions) malloc/new/new[], --alloc-fns, etc.
>->53.85% (56B) 0x3D1709B85F: std::string::_Rep::_S_create(unsigned long,
>unsigned long, std::allocator<char> const&) (in /usr/lib64/libstdc++.so.6.0.8)
>| ->26.92% (28B) 0x3D1709D10F: std::string::_M_mutate(unsigned long, unsigned
>long, unsigned long) (in /usr/lib64/libstdc++.so.6.0.8)
>| | ->26.92% (28B) 0x3D1709D28A: std::string::_M_replace_safe(unsigned long,
>unsigned long, char const*, unsigned long) (in /usr/lib64/libstdc++.so.6.0.8)
>| | ->26.92% (28B) 0x4009B2: main (test1.c:6)
>| |
>| ->26.92% (28B) 0x3D1709C363: ??? (in /usr/lib64/libstdc++.so.6.0.8)
>| ->26.92% (28B) 0x3D1709C510: std::basic_string<char,
>std::char_traits<char>, std::allocator<char> >::basic_string(char const*,
>std::allocator<char> const&) (in /usr/lib64/libstdc++.so.6.0.8)
>| ->26.92% (28B) 0x4009E3: main (test1.c:8)
>|
>->07.69% (8B) 0x4009CD: main (test1.c:8)
>
>/*********************
>
>
>Why valgrind is showing stack variables in heap. Any idea.
>
>
>
std::string is a std::vector<char>. A vector is dynamically sized (data can be
added or removed ay any time), so it must allocate space from the heap to store
the data inside. There is no special optimization for a stack variable.
All of this applies to every container object, so practically any program that
uses C++ libraries will allocate space from the heap.
--
David Chapman [email protected] Chapman Consulting -- San Jose, CA------------------------------------------------------------------------------
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