[llvm-dev] LLVM IR linking separate function definitions in header files in single IR

[hameeza ahmed via llvm-dev]

Hello,
If we have @_Znwm(i64 32) this,
It means allocation of 32 bytes on heap right?

Thank You

On Sun, Jan 6, 2019 at 10:15 PM Mehdi AMINI <joker.eph at gmail.com> wrote:

>
>
> On Sun, Jan 6, 2019 at 3:36 AM hameeza ahmed <hahmed2305 at gmail.com> wrote:
>
>> Thank You..
>> I am observing memory allocation instructions malloc and new operator in
>> LLVM IR.
>> In my considered benchmark memory is allocated using new operator as
>> follows.
>> *return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));*
>>
>> How can I observe such allocations in IR? I mean which instruction in IR
>> is equivalent to above code i.e new operator.
>>
>
> I think I answered in my previous email: "The line you are posting above
> is present multiple times, for example in the
> function _ZN9__gnu_cxx13new_allocatorINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEE8allocateEmPKv"
> and: "Calls to @_Znwm are allocating memory."
>
> Did you search for these calls in the IR? Can you clarify what else you
> need?
>
> --
> Mehdi
>
>
>
>>
>> Please help
>> Thank You
>>
>> On Sun, Jan 6, 2019 at 4:32 AM Mehdi AMINI <joker.eph at gmail.com> wrote:
>>
>>>
>>>
>>> On Sat, Jan 5, 2019 at 3:08 PM hameeza ahmed <hahmed2305 at gmail.com>
>>> wrote:
>>>
>>>> Thank You...
>>>> My issue is i m observing malloc instructions in LLVM IR.. When I
>>>> compiled certain benchmark codes i.e graphbig. They consume memory but when
>>>> I see IR there is no malloc..
>>>>
>>>
>>> This is confusing, you first wrote that you are "observing malloc
>>> instructions in LLVM IR" but then you wrote "when I see IR there is no
>>> malloc".
>>>
>>>
>>>
>>>> By observing in detail i came to know following line which exist in
>>>> header file new_allocator.h is taking memory;
>>>> *return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));*
>>>>
>>>
>>> Your original question was "I want to have a single IR with all the
>>> definitions of the called functions that are implemented in header files".
>>>
>>> The IR you're sending contains all the code defined in the header. The
>>> line you are posting above is present multiple times, for example in the
>>> function _ZN9__gnu_cxx13new_allocatorINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEEE8allocateEmPKv
>>>
>>>
>>>
>>>> but in IR there is no malloc...
>>>>
>>>
>>> Do you have calls to malloc in the source code?
>>>
>>>
>>>> how can i identify such instructions in IR...by call void @_ZN??
>>>> My IR is attached here..
>>>>
>>>
>>> Calls to @_Znwm are allocating memory. They are not implemented in a
>>> header:
>>> https://code.woboq.org/gcc/libstdc++-v3/libsupc++/new_op.cc.html#50
>>> (see the call to malloc there).
>>>
>>> In general, calls to malloc can likely be caught at runtime: run in a
>>> debugger and break into malloc.
>>>
>>> best,
>>>
>>> --
>>> Mehdi
>>>
>>>
>>>
>>>
>>>>
>>>> Please help.
>>>>
>>>> On Fri, Jan 4, 2019 at 4:21 AM Mehdi AMINI <joker.eph at gmail.com> wrote:
>>>>
>>>>>
>>>>>
>>>>> On Tue, Jan 1, 2019 at 1:41 PM hameeza ahmed via llvm-dev <
>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>
>>>>>> Hello,
>>>>>> I have different codes with separate files with functions
>>>>>> implemented. I want to view all function definitions/ instructions in
>>>>>> single IR. I am able to do this by llvm-link for codes which have
>>>>>> definition implemented in .c files...
>>>>>> But there are some codes which have definitions instructions in
>>>>>> header files. These functions are called from .c file. I want to have a
>>>>>> single IR with all the definitions of the called functions that are
>>>>>> implemented in header files..
>>>>>>
>>>>>> How to do this?
>>>>>> Please help...
>>>>>>
>>>>>
>>>>> I assume that your  "function defined in a header"  are marked as
>>>>> inline? There is no semantic concept of "header" in C/C++: moving code from
>>>>> a .c to a .h (or renaming a file) does not change anything to what the
>>>>> compiler will do with it.
>>>>>
>>>>> Depending on the language (GNU-C89, C99 vs C++, see here:
>>>>> https://en.wikipedia.org/wiki/Inline_function ), the semantic of
>>>>> inline functions is different.
>>>>> If you can provide an minimal example it would be easier.
>>>>>
>>>>> Best,
>>>>>
>>>>> --
>>>>> Mehdi
>>>>>
>>>>>
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