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[Bug translator/14434] New: dwflpp sometimes caches incomplete class_type
- From: "mjw at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sourceware dot org
- Date: Sun, 05 Aug 2012 18:25:45 +0000
- Subject: [Bug translator/14434] New: dwflpp sometimes caches incomplete class_type
- Auto-submitted: auto-generated
http://sourceware.org/bugzilla/show_bug.cgi?id=14434
Bug #: 14434
Summary: dwflpp sometimes caches incomplete class_type
Product: systemtap
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: translator
AssignedTo: systemtap@sourceware.org
ReportedBy: mjw@redhat.com
Classification: Unclassified
Take the following program:
::::::::::::::
header.hxx
::::::::::::::
#include <malloc.h>
class Heap
{
private:
char *_memory;
size_t _size;
public:
Heap();
void* allocate (size_t size);
static size_t header_size();
};
::::::::::::::
heap.cxx
::::::::::::::
#include "header.hxx"
size_t
Heap::header_size ()
{
return 42;
}
Heap::Heap()
{
_size = header_size () + 32;
_memory = (char *) malloc (_size);
}
void*
Heap::allocate(size_t size)
{
_size += size;
return _memory + header_size();
}
::::::::::::::
main.cxx
::::::::::::::
#include "header.hxx"
int size (int resize)
{
return (int)Heap::header_size() - resize;
}
int
main (int argc, char **argv)
{
return size (argc);
}
Compile it with g++ 4.7.1:
$ g++ -g -O2 -c main.cxx
$ g++ -g -O2 -c heap.cxx
$ g++ -g main.o heap.o -o prog
Now try inspecting it with stap a couple of times and notice it occasionally
fails. In this example we are interested in the offset of one of the field
members of the Heap class and use @cast on address zero to get it:
$ stap -p2 -v -e 'probe process("./prog").function("main") { printf("_size
member offset: %d\n", &@cast(0, "Heap")->_size); }' > /dev/null
Pass 1: parsed user script and 96 library script(s) using
212776virt/34756res/3024shr/32128data kb, in 110usr/10sys/127real ms.
Pass 2: analyzed script: 1 probe(s), 1 function(s), 0 embed(s), 0 global(s)
using 215824virt/36464res/3588shr/33056data kb, in 10usr/0sys/7real ms.
$ stap -p2 -v -e 'probe process("./prog").function("main") { printf("_size
member offset: %d\n", &@cast(0, "Heap")->_size); }' > /dev/null
Pass 1: parsed user script and 96 library script(s) using
212776virt/34756res/3024shr/32128data kb, in 110usr/10sys/129real ms.
Pass 2: analyzed script: 1 probe(s), 1 function(s), 0 embed(s), 0 global(s)
using 215824virt/36464res/3588shr/33056data kb, in 10usr/0sys/7real ms.
$ stap -p2 -v -e 'probe process("./prog").function("main") { printf("_size
member offset: %d\n", &@cast(0, "Heap")->_size); }' > /dev/null
Pass 1: parsed user script and 96 library script(s) using
212776virt/34756res/3024shr/32128data kb, in 120usr/10sys/128real ms.
semantic error: unable to find member '_size' for class Heap: operator '->' at
<input>:1:97
source: probe process("./prog").function("main") { printf("_size member
offset: %d\n", &@cast(0, "Heap")->_size); }
^
Pass 2: analyzed script: 1 probe(s), 0 function(s), 0 embed(s), 0 global(s)
using 213716virt/36340res/3476shr/33052data kb, in 10usr/0sys/7real ms.
Pass 2: analysis failed. Try again with another '--vp 01' option.
Isn't that weird! It worked 2 out of 3 times, but then it suddenly failed.
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