[llvm-dev] LLVM IR linking separate function definitions in header files in single IR (original) (raw)

Mehdi AMINI via llvm-dev llvm-dev at lists.llvm.org
Sun Feb 10 10:47:06 PST 2019

On Sun, Feb 10, 2019 at 8:21 AM hameeza ahmed <hahmed2305 at gmail.com> wrote:

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

Yes, that's right. If you look at the link I posted earlier to the source code, the argument is passed directly to malloc.

-- Mehdi

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 staticcast<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_gnucxx13newallocatorINSt7_cxx1112basicstringIcSt11chartraitsIcESaIcEEEE8allocateEmPKv" 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 newallocator.h is taking memory; _return staticcast<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_gnucxx13newallocatorINSt7_cxx1112basicstringIcSt11chartraitsIcESaIcEEEE8allocateEmPKv 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++/newop.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/Inlinefunction ), the semantic of inline functions is different. If you can provide an minimal example it would be easier. Best, -- Mehdi -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20190210/d3233401/attachment-0001.html>

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