Re: [Qemu-devel] [PATCH v3 22/22] qidl: unit tests and build infrastructure

[Kevin Wolf]

Am 12.10.2012 23:39, schrieb Michael Roth:
> On Fri, Oct 05, 2012 at 10:24:30AM +0200, Paolo Bonzini wrote:
>> Il 04/10/2012 19:33, Michael Roth ha scritto:
>>> +
>>> +%.qidl.c: %.c $(SRC_PATH)/qidl.h $(addprefix $(SRC_PATH)/scripts/,lexer.py 
>>> qidl.py qidl_parser.py qapi.py qapi_visit.py)
>>> +   $(call rm -f $(*D)/qidl-generated/$(*F).qidl.c)
>>> +   $(if $(strip $(shell grep "QIDL_ENABLE()" $< 1>/dev/null && echo 
>>> "true")), \
>>> +     $(call quiet-command, \
>>> +       $(CC) $(QEMU_INCLUDES) $(QEMU_CFLAGS) $(CFLAGS) -E -c -DQIDL_GEN $< 
>>> | \
>>> +       $(PYTHON) $(SRC_PATH)/scripts/qidl.py \
>>> +       --output-filepath=$(*D)/qidl-generated/$(*F).qidl.c || [ "$$?" -eq 
>>> 2 ], \
>>> +       "qidl PP $(*D)/$(*F).c"),)
>>> +%.o: %.c %.qidl.c
>>> +   $(if $(strip $(shell test -f $(*D)/qidl-generated/$(*F).qidl.c && echo 
>>> "true")), \
>>> +     $(call quiet-command, \
>>> +       $(CC) $(QEMU_INCLUDES) $(QEMU_CFLAGS) $(QEMU_DGFLAGS) $(CFLAGS) -c \
>>> +           -DQIDL_ENABLED -include $< -o $@ 
>>> $(*D)/qidl-generated/$(*F).qidl.c, \
>>> +           "qidl CC $@"), \
>>> +     $(call quiet-command, \
>>> +       $(CC) $(QEMU_INCLUDES) $(QEMU_CFLAGS) $(QEMU_DGFLAGS) $(CFLAGS) -c \
>>> +         -o $@ $<,"  CC    $@"))
>>
>>
>> Because the .qidl.c files are not created for files without a QIDL_ENABLE()
>> directive, all those files will be grepped on every invocation of the 
>> makefile.
>>
>> It is better to define the list of QIDL_ENABLEd files in an auxiliary 
>> makefile
>> like this (untested):
> 
> Thanks for the suggestion / example.
> 
> FYI, I tried to get this working but didn't manage to get it in for v4. 
> Everything
> seems to be falling back to the non-qidl %o: target, and I haven't had time to
> debug it.
> 
> FWIW, it doesn't seem to be a major factor performance-wise. Current build
> times on my laptop are (for all-target builds):
> 
> QIDL v4:
>  real    8m35.383s
>  user    31m1.844s
>  sys     1m33.998s
> 
> upstream:
>  real    8m28.181s
>  user    30m44.983s
>  sys     1m29.926s

Isn't the more interesting case that I only touched block/qcow2.c and
run make to update my binaries? I haven't really looked at the code, but
Paolo's comment suggests that even in this case a lot of files would be
grepped, and I think that losing a few seconds in such cases would
really hurt.

Kevin