On Thu, 8 May 2014, Janne Grunau wrote:
On 2014-05-07 18:49:41 +0300, Martin Storsjö wrote:
On Wed, 7 May 2014, Janne Grunau wrote:
On 2014-05-07 16:29:54 +0300, Martin Storsjö wrote:
On Wed, 7 May 2014, Janne Grunau wrote:
On 2014-05-07 14:00:11 +0300, Martin Storsjö wrote:
the normal compiler. If specified manually (with --as="gaspp armasm"
or so), configure tries to detect the dependency generation
mechanism for this (and often ends up with something that doesn't
produce proper dependencies).
Does it need more passthrough options (-v|--version|-dumpversion) to detect
assembler type correctly? That change made it work with gcc and clang.
Right, yes, this seems to help there.
For the armasm case, I end up with a '-.d' generated while I run
configure, but other than that it manages to detect a working way to
create the deps which work while building. I'll look into what part
of it creates the -.d file during configure.
Are you sure -.d is only used during configure?
Sorry no, I was mistaken, it does get generated all the time when
building as well.
Sounds a lot like 9e057f53aa8549e94b7f52a67f69ce94d607da0a for
clang. The dependency information is generated during the
preprocess phase and -MMD without -MF derives the dependency file
name from the output name which is '-'.
In this case it's something completely different actually; configure
chooses a separate dependency generation step when building, and
that step works fine. When building an object file, make does the
following (unrelated parameters stripped for brevity):
gas-preprocessor-git.pl -as-type armasm -- armasm -MM libavcodec/arm/int_neon.S | sed -e
"/^#.*/d" -e "s,^[[:space:]]*int_neon\\.o,libavcodec/arm/int_neon.o," >
libavcodec/arm/int_neon.d
gas-preprocessor-git.pl -as-type armasm -- armasm -MD -march=armv7-a -c -o
libavcodec/arm/int_neon.o libavcodec/arm/int_neon.S
The key here is the -MD option when compiling; it's actually the
MSVC flag for choosing a dynamically linked crt (that I've set in
--extra-cflags) which gets passed on here.
nice conflict of option names. MSVC needs the flag during compilation? It
sounds more like an linker flag. If it's not in --extra-cflags it won't be
added to asflags.
Yes, it's needed during compilation.
The full story is that MSVC adds linker options into the built object
files. (I kid you not - an MSVC object file contains strings such as
/DEFAULTLIB:"LIBCMT" /DEFAULTLIB:"OLDNAMES". In some odd setups, Visual
Studio project files then add extra linker flags to counter these, such as
/nodefaultlib:oldnames.) The linker then aggregates all linker options
from the object files and include them into the link. The choice of CRT is
one such linker option which gets passed this way and thus needs to be
passed via the cflags.
This gets included in the
preprocessing step in gas-preprocessor, where cpp writes the bogus
-.d file.
What's the least ugly way of handling this? Stripping out
/^-M(D|T)d?$/ from the preprocessor commands when using armasm mode?
Identifying armasm in probe_cc and and adding an asflags_filter to remove it
is the other solution I can think of. It's also a little ugly since -MD is
not per se a unsupported option. It just doesn't make sense for us and gets
unintentionally added under certain conditions.
If you expect similar problems in other projects removing -MD in
gas-preprocessor is preferable. Since armasm doesn't seem to support -MF and
-MT gas-preprocessor can't generate dependency files safely.
Yes, -MD can easily end up as parameter to gas-preprocessor via cflags in
other projects as well. I'll send a patch implementing this then.
// Martin
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