Re: [PATCH][gdb/testsuite] Fix shlib compilation with target board unix/-pie/-fPIE

Tom de Vries
2020-12-16T17:22:37Z

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.

Thanks,
- Tom

> Otherwise, LGTM.
>
> Simon
>