On 12/16/20 6:22 PM, Tom de Vries wrote:
> On 12/14/20 6:21 PM, Simon Marchi wrote:
>> On 2020-12-13 11:41 a.m., Tom de Vries wrote:
>>> Hi,
>>>
>>> When running test-case gdb.base/info-shared.exp with target board
>>> unix/-pie/-fPIE, we run into:
>>> ...
>>> spawn -ignore SIGHUP gcc -fno-stack-protector \
>>>   outputs/gdb.base/info-shared/info-shared-solib1.c.o \
>>>   -fdiagnostics-color=never -fPIC -shared -Wl,-soname,info-shared-solib1.so \
>>>   -lm -fPIE -pie -o outputs/gdb.base/info-shared/info-shared-solib1.so^M
>>> ld: Scrt1.o: in function `_start':^M
>>> start.S:104: undefined reference to `main'^M
>>> collect2: error: ld returned 1 exit status^M
>>> compiler exited with status 1
>>> ...
>>>
>>> The intention of the -pie/-fPIE flags is to build and test PIE executables on
>>> platforms where that is not the default.  However, the flags clash with the
>>> flags required to build shared libraries.
>>>
>>> Fix this by filtering out PIE-related flags out of the multilib_flags settings
>>> in compile_shared_lib.
>>>
>>> Tested on x86_64-linux.
>>>
>>> Any comments?
>>>
>>> Thanks,
>>> - Tom
>>>
>>> [gdb/testsuite] Fix shlib compilation with target board unix/-pie/-fPIE
>>>
>>> ---
>>>  gdb/testsuite/lib/gdb.exp | 39 ++++++++++++++++++++++++++++++++++++++-
>>>  1 file changed, 38 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
>>> index e35d236018..071b5afa99 100644
>>> --- a/gdb/testsuite/lib/gdb.exp
>>> +++ b/gdb/testsuite/lib/gdb.exp
>>> @@ -4283,7 +4283,7 @@ proc gdb_compile_pthreads {source dest type options} {
>>>
>>>  # Build a shared library from SOURCES.
>>>
>>> -proc gdb_compile_shlib {sources dest options} {
>>> +proc gdb_compile_shlib_1 {sources dest options} {
>>>      set obj_options $options
>>>
>>>      set ada 0
>>> @@ -4416,6 +4416,43 @@ proc gdb_compile_shlib {sources dest options} {
>>>      return ""
>>>  }
>>>
>>> +# Build a shared library from SOURCES.  Ignore target boards PIE-related
>>> +# multilib_flags.
>>> +
>>> +proc gdb_compile_shlib {sources dest options} {
>>> +    global board
>>> +
>>> +    # Save multilib_flags.
>>> +    set board [target_info name]
>>> +    set save_multilib_flag [board_info $board multilib_flags]
>>> +
>>> +    # Ignore PIE-related setting in multilib_flags.
>>> +    set multilib_flag ""
>>> +    foreach op $save_multilib_flag {
>>> +	if { $op == "-pie" || $op == "-no-pie" \
>>> +		 || $op == "-fPIE" || $op == "-fno-PIE"} {
>>> +	} else {
>>> +	    append multilib_flag " $op"
>>> +	}
>>> +    }
>>> +    unset_board_info "multilib_flags"
>>> +    set_board_info multilib_flags "$multilib_flag"
>>> +    set code [catch {gdb_compile_shlib_1 $sources $dest $options} result]
>>> +
>>> +    # Restore multilib_flags.
>>> +    unset_board_info "multilib_flags"
>>> +    set_board_info multilib_flags $save_multilib_flag
>>> +
>>> +    if {$code == 1} {
>>> +	global errorInfo errorCode
>>> +	return -code error -errorinfo $errorInfo -errorcode $errorCode $result
>>> +    } elseif {$code > 1} {
>>> +	return -code $code $result
>>> +    }
>>> +
>>> +    return $result
>>
>> That sounds reasonable.  I wonder if the lines above could be simplified
>> to:
>>
>>   if {$code == 1} {
>>       ...
>>   }
>>
>>   return -code $code $result
>>
>> IOW, if it's fine to return an explicit -code even if $code is 0 / OK.
>>
> 
> Thanks for the review.
> 
> I copied this code from gdb_do_cache_wrap, so I left it as is for the
> commit.
> 
> This sounds like a good idea for a more broad refactoring.
> 

I thought this over a bit more, and came to the realization that what
this does is similar to save_vars, only for target board_info.

So, how about this refactoring?

Thanks,
- Tom