[NEWS/RFA] Re: [gdbserver] x86 agent expression bytecode compiler (speed up conditional tracepoints)

[Doug Evans]

Yeah.
Until it gets fixed a workaround is to compile linux-x86-low.c with -O0.


On Sat, Jun 19, 2010 at 9:12 AM, Hui Zhu <teawater@gmail.com> wrote:
> lubuntu 10.04:
>
> make[4]: ?????? `/home/teawater/gdb/bgdball/gdb/gdbserver'
> rm -f gdbserver
> gcc -Wall -g -O2    -I. -I../../../src/gdb/gdbserver
> -I../../../src/gdb/gdbserver/../common
> -I../../../src/gdb/gdbserver/../regformats
> -I../../../src/gdb/gdbserver/../../include
> -Wl,--dynamic-list=../../../src/gdb/gdbserver/proc-service.list -o
> gdbserver inferiors.o regcache.o remote-utils.o server.o signals.o
> target.o utils.o version.o mem-break.o hostio.o event-loop.o
> tracepoint.o xml-builtin.o i386-linux.o i386-avx-linux.o
> i386-mmx-linux.o linux-low.o linux-x86-low.o i386-low.o i387-fp.o
> hostio-errno.o thread-db.o proc-service.o  \
>          -ldl
> linux-x86-low.o: In function `i386_emit_void_call_2':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2426:
> undefined reference to `end_i386_void_call_2_a'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2426:
> undefined reference to `start_i386_void_call_2_a'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2426:
> undefined reference to `start_i386_void_call_2_a'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2447:
> undefined reference to `end_i386_void_call_2_b'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2447:
> undefined reference to `start_i386_void_call_2_b'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2447:
> undefined reference to `start_i386_void_call_2_b'
> linux-x86-low.o: In function `i386_emit_int_call_1':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2398:
> undefined reference to `end_i386_int_call_1_a'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2398:
> undefined reference to `start_i386_int_call_1_a'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2398:
> undefined reference to `start_i386_int_call_1_a'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2412:
> undefined reference to `end_i386_int_call_1_c'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2412:
> undefined reference to `start_i386_int_call_1_c'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2412:
> undefined reference to `start_i386_int_call_1_c'
> linux-x86-low.o: In function `i386_emit_swap':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2364:
> undefined reference to `end_i386_swap'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2364:
> undefined reference to `start_i386_swap'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2364:
> undefined reference to `start_i386_swap'
> linux-x86-low.o: In function `i386_emit_zero_ext':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2343:
> undefined reference to `end_i386_zero_ext_8'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2343:
> undefined reference to `start_i386_zero_ext_8'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2343:
> undefined reference to `start_i386_zero_ext_8'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2353:
> undefined reference to `end_i386_zero_ext_32'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2353:
> undefined reference to `start_i386_zero_ext_32'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2353:
> undefined reference to `start_i386_zero_ext_32'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2348:
> undefined reference to `end_i386_zero_ext_16'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2348:
> undefined reference to `start_i386_zero_ext_16'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2348:
> undefined reference to `start_i386_zero_ext_16'
> linux-x86-low.o: In function `i386_emit_stack_flush':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2332:
> undefined reference to `end_i386_stack_flush'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2332:
> undefined reference to `start_i386_stack_flush'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2332:
> undefined reference to `start_i386_stack_flush'
> linux-x86-low.o: In function `i386_emit_pop':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2324:
> undefined reference to `end_i386_pop'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2324:
> undefined reference to `start_i386_pop'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2324:
> undefined reference to `start_i386_pop'
> linux-x86-low.o: In function `i386_emit_goto':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2227:
> undefined reference to `end_i386_goto'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2227:
> undefined reference to `start_i386_goto'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2227:
> undefined reference to `start_i386_goto'
> linux-x86-low.o: In function `i386_emit_if_goto':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2209:
> undefined reference to `end_i386_if_goto'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2209:
> undefined reference to `start_i386_if_goto'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2209:
> undefined reference to `start_i386_if_goto'
> linux-x86-low.o: In function `i386_emit_ref':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2187:
> undefined reference to `end_i386_ref1'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2187:
> undefined reference to `start_i386_ref1'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2187:
> undefined reference to `start_i386_ref1'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2199:
> undefined reference to `end_i386_ref8'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2199:
> undefined reference to `start_i386_ref8'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2199:
> undefined reference to `start_i386_ref8'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2191:
> undefined reference to `end_i386_ref2'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2191:
> undefined reference to `start_i386_ref2'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2191:
> undefined reference to `start_i386_ref2'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2195:
> undefined reference to `end_i386_ref4'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2195:
> undefined reference to `start_i386_ref4'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2195:
> undefined reference to `start_i386_ref4'
> linux-x86-low.o: In function `i386_emit_less_unsigned':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2165:
> undefined reference to `end_i386_less_unsigned'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2165:
> undefined reference to `start_i386_less_unsigned'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2165:
> undefined reference to `start_i386_less_unsigned'
> linux-x86-low.o: In function `i386_emit_less_signed':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2146:
> undefined reference to `end_i386_less_signed'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2146:
> undefined reference to `start_i386_less_signed'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2146:
> undefined reference to `start_i386_less_signed'
> linux-x86-low.o: In function `i386_emit_equal':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2128:
> undefined reference to `end_i386_equal'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2128:
> undefined reference to `start_i386_equal'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2128:
> undefined reference to `start_i386_equal'
> linux-x86-low.o: In function `i386_emit_bit_not':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2120:
> undefined reference to `end_i386_bit_not'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2120:
> undefined reference to `start_i386_bit_not'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2120:
> undefined reference to `start_i386_bit_not'
> linux-x86-low.o: In function `i386_emit_bit_xor':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2111:
> undefined reference to `end_i386_xor'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2111:
> undefined reference to `start_i386_xor'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2111:
> undefined reference to `start_i386_xor'
> linux-x86-low.o: In function `i386_emit_bit_or':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2102:
> undefined reference to `end_i386_or'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2102:
> undefined reference to `start_i386_or'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2102:
> undefined reference to `start_i386_or'
> linux-x86-low.o: In function `i386_emit_bit_and':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2093:
> undefined reference to `end_i386_and'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2093:
> undefined reference to `start_i386_and'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2093:
> undefined reference to `start_i386_and'
> linux-x86-low.o: In function `i386_emit_log_not':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2082:
> undefined reference to `end_i386_log_not'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2082:
> undefined reference to `start_i386_log_not'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2082:
> undefined reference to `start_i386_log_not'
> linux-x86-low.o: In function `i386_emit_ext':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2057:
> undefined reference to `end_i386_ext_8'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2057:
> undefined reference to `start_i386_ext_8'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2057:
> undefined reference to `start_i386_ext_8'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2070:
> undefined reference to `end_i386_ext_32'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2070:
> undefined reference to `start_i386_ext_32'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2070:
> undefined reference to `start_i386_ext_32'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2064:
> undefined reference to `end_i386_ext_16'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2064:
> undefined reference to `start_i386_ext_16'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2064:
> undefined reference to `start_i386_ext_16'
> linux-x86-low.o: In function `i386_emit_sub':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2020:
> undefined reference to `end_i386_sub'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2020:
> undefined reference to `start_i386_sub'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2020:
> undefined reference to `start_i386_sub'
> linux-x86-low.o: In function `i386_emit_add':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2011:
> undefined reference to `end_i386_add'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2011:
> undefined reference to `start_i386_add'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2011:
> undefined reference to `start_i386_add'
> linux-x86-low.o: In function `i386_emit_epilogue':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:1999:
> undefined reference to `end_i386_epilogue'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:1999:
> undefined reference to `start_i386_epilogue'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:1999:
> undefined reference to `start_i386_epilogue'
> linux-x86-low.o: In function `i386_emit_prologue':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:1989:
> undefined reference to `end_i386_prologue'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:1989:
> undefined reference to `start_i386_prologue'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:1989:
> undefined reference to `start_i386_prologue'
> linux-x86-low.o: In function `i386_emit_reg':
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2302:
> undefined reference to `end_i386_reg_a'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2302:
> undefined reference to `start_i386_reg_a'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2302:
> undefined reference to `start_i386_reg_a'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2311:
> undefined reference to `end_i386_reg_b'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2311:
> undefined reference to `start_i386_reg_b'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2311:
> undefined reference to `start_i386_reg_b'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2316:
> undefined reference to `end_i386_reg_c'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2316:
> undefined reference to `start_i386_reg_c'
> /home/teawater/gdb/bgdball/gdb/gdbserver/../../../src/gdb/gdbserver/linux-x86-low.c:2316:
> undefined reference to `start_i386_reg_c'
> collect2: ld returned 1 exit status
> make[4]: *** [gdbserver] ?? 1
> make[4]:?????? `/home/teawater/gdb/bgdball/gdb/gdbserver'
> make[3]: *** [subdir_do] ?? 1
> make[3]:?????? `/home/teawater/gdb/bgdball/gdb'
> make[2]: *** [all] ?? 2
> make[2]:?????? `/home/teawater/gdb/bgdball/gdb'
> make[1]: *** [all-gdb] ?? 2
> make[1]:?????? `/home/teawater/gdb/bgdball'
>
>
> On Fri, Jun 18, 2010 at 02:03, Michael Snyder <msnyder@vmware.com> wrote:
>> Stan Shebs wrote:
>>>
>>> Pedro Alves wrote:
>>>>
>>>> On Wednesday 16 June 2010 20:12:44, Stan Shebs wrote:
>>>>
>>>>>
>>>>> Doug Evans wrote:
>>>>>
>>>>>>
>>>>>> On Mon, Jun 14, 2010 at 3:19 PM, Pedro Alves <pedro@codesourcery.com>
>>>>>> wrote:
>>>>>>
>>>>>>>
>>>>>>> Thanks.  I've checked the whole thing in.
>>>>>>>
>>>>>>
>>>>>> I'm getting build failures that go away when compiling linux-x86-low.c
>>>>>> with -g.
>>>>>>
>>>>>> gcc is optimizing out the skipped over stuff I believe.
>>>>>>
>>>>>
>>>>> Hmm, this particular trickery was my idea, but it always seemed
>>>>> vulnerable to ever-smarter optimization.  Does anybody have any better
>>>>> strategy?  Declaring the asm volatile didn't work, because the compiler was
>>>>> whacking everything around it.
>>>>>
>>>>> The other approach is to build up instructions from bitfields, which is
>>>>> reliable but needs a lot of setup and helper routines.
>>>>>
>>>>
>>>> Quick thought: can we stick a couple of __attribute__((used))'s in the
>>>> macro, so the compiler doesn optimized things away, thinking they're
>>>> unused (given the uses are behind asm)?
>>>>
>>>
>>> The compiler is discarding the code with the definitions of the labels,
>>> because it's thinking they are maybe somewhere else in the program (the
>>> error is at link time).  Moving the labels into C code would fix that I
>>> think, but then it's hard to guarantee that the compiler won't sneak in a
>>> bit of code between label and asm sequence.
>>
>> Hurrr.  Code that depends on such deep knowledge of the compiler's
>> behavior is wrong code, IMO.
>>
>>
>