[patch, avr] Fix mmcu to specs issues

[Pitchumani Sivanupandi]

On Tuesday 26 July 2016 06:00 PM, Georg-Johann Lay wrote:
> On 26.07.2016 12:20, Pitchumani Sivanupandi wrote:
>> avr-gcc expected to find the device specs in the search paths 
>> specified. But
>> it doesn't work as expected when device specs in different place than 
>> the
>> installed location.
>>
>> Example-1:
>> avr-gcc wrongly assumes the device specs will be in first identified
>> 'device-specs' folder in prefix path. avr-gcc natively supports device
>> at90pwm1, but complains as it couldn't find the specs file in the first
>> 'device-specs' directory in the search path.
>>
>>
>> $ avr-gcc test.c -mmcu=at90pwm1 -B /home/install/dev/atxmega128a1u/
>>
>> avr-gcc: error: cannot access device-specs for _at90pwm1_ expected at
>
> Are the "_"s literally? Then the spec file name should be 
> "specs-_at90pwm1_".
No, It was mangled character shown by my terminal for format specifier 
"%qs" in printf.
Ignore it.
...
>> Example-2:
>> Similar issue happens when -flto option is enabled and device specs 
>> in custom
>> search path.
>>
>> atxmega128a1u device specs in custom path and that is passed with -B 
>> option.
>> Architecture spec files such as specs-avrxmega7 will be in installed 
>> location.
>>
>> $ avr-gcc test.c -mmcu=atxmega128a1u -flto -B 
>> /home/install/dev/atxmega128a1u/
>>
>> avr-gcc: error: cannot access device-specs for _avrxmega7_ expected at
>> _/home/install/dev/atxmega128a1u/device-specs/specs-avrxmega7_
>> avr-gcc: note: supported core architectures: avr2 avr25 avr3 avr31 
>> avr35 avr4
>> avr5 avr51 avr6 avrxmega2 avrxmega4 avrxmega5 avrxmega6 avrxmega7 
>> avrtiny avr1
>> avr-gcc: note: you can provide your own specs files, see
>> <http://gcc.gnu.org/onlinedocs/gcc/Spec-Files.html> for details
>> lto-wrapper: fatal error: avr-gcc returned 1 exit status
>> compilation terminated.
>> /home/avr-trunk/install/lib/gcc/avr/7.0.0/../../../../avr/bin/ld: error:
>> lto-wrapper failed
>> collect2: error: ld returned 1 exit status
>>
>> Attached patch to address these issues.
>>
>> Fix:
>> Replace device-specs-file spec function with mmcu-to-device-specs. 
>> This will
>> not assume that specs files are in first identified device-specs 
>> directory.
>> Instead this spec function will let gcc identify the absolute path of 
>> specs file
>> using spec string "device-specs-file (device-specs/specs-<mcu>%s)".
>
> IIUC this leads to problems with LTO and when the install path 
> contains spaces which windows distros usually have.  The problem is 
> that the spec function cannot escape the spaces as it would need more 
> than 1 escape level.
>
> It might also be the case that -mmcu= is specified more than once 
> (with the same MCU), but I don't remember exactly in which situations 
> this happens... Doesn't this lead to inclusion of more than one 
> specs-file?

Yes, it lead to space problem.

Modified the patch because of path with spaces problem. When LTO 
enabled, multiple specs-file are
included as -mmcu=<arch> is fed back to gcc. It happens with/ without of 
this patch.
e.g. For atmega164p, device's and architecture's specs file given when 
invoking collect2.
  -specs=device-specs/specs-atmega164p -specs=device-specs/specs-avr5

Attached new patch. It just removes the conditions that led to 
originally stated issues.
(In driver-avr.c:avr_devicespecs_file)
Removed first condition as -mmcu=avr* shall come when LTO enabled. 
Second condition to
check absolute path is wrong as the specfile_name composed here will not 
be available
if the specs file is not present in first 'device-specs' directory.

With this approach, we can't issue 'descriptive' error for unavailable 
specs-file.
But, avr-gcc will issue below error if specs file is not found.
$ avr-gcc -mmcu=unknown test.c
avr-gcc: error: device-specs/specs-unknown: No such file or directory

Is that Ok?

Regards,
Pitchumani

gcc/ChangeLog

2016-07-28  Pitchumani Sivanupandi <pitchumani.s@atmel.com>

     * config/avr/driver-avr.c (specfiles_doc_url): Remove.
     (avr_diagnose_devicespecs_error): Remove.
     (avr_devicespecs_file): Remove conditions to check specs-file,
     let -specs= option handler do the validation.
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