Hallo Martin,
On 10/11/2020 13:05, Martin Liška wrote:
On 11/9/20 6:45 PM, Sebastian Huber wrote:
Hello,
Hello.
There was a similar need some time ago:
https://gcc.gnu.org/legacy-ml/gcc/2019-11/msg00009.html
Please take a look for a possible inspiration.
thanks for the pointer.
I would like to use the -ftest-coverage -fprofile-arcs support on a
bare metal system (no operating system or very early stages in the
system startup). In this environment I cannot use the gcov info
registration via a constructor and __gcov_init(), because there may
be some other (more complex) constructors registered which cannot be
called at this stage.. Would it be acceptable to add a compiler
option which changes the gcov info registration via a constructor to
a linker set? If enabled, then for each translation unit (see
coverage_obj_init()) a pointer to the gcov info is placed into a
special linker section (for example .gcov_info). The linker script
collects all .gcov_info data and adds a begin/end symbol. The runtime
support can then iterate over all linker section entries (pointers to
struct gcov_info) to dump the aggregated gcov data during program
termination. Would such changes be acceptable for GCC integration or
is this too specific?
That's definitely something we can support. Similarly to the linked
message, are you capable of using
normal system I/O to stream .gcda files?
I cannot use I/O to files. I also cannot use dynamic memory (e.g.
malloc()). This is actually not an issue, since it is very easy to dump
the gcov info via a simple character output function as plain text. In
the Linux kernel see for example convert_to_gcda() in
"kernel/gcov/gcc_4_7.c". Instead of copying the data to a buffer you can
directly output the data via some printk() function. On the host
computer you can collect the text and generate the .gcda files.
I guess the first thing we need is a name for the option. What about:
-fprofile-info-section
-fprofile-info-section=name
Register a pointer to the profile information generated by
-fprofile-arcs in the named section for each translation unit. If name
is not given, then .gcov_info will be used. This option disables the
profile information registration through a constructor and it disables
the profile information processing through a destructor. This option can
be used to support profiling in environments which do not support
constructors and destructors. The linker could collect the content of
the named section in a continuous memory block and add begin and end
symbols. The runtime support could dump the profiling information
registered in this linker set during program termination to a serial
line for example.
--
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