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

Doug Evans
2010-06-16T18:57:10Z

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.

/* Our general strategy for emitting code is to avoid specifying raw
bytes whenever possible, and instead copy a block of inline asm
that is embedded in the function. This is a little messy, because
we need to keep the compiler from discarding what looks like dead
code, plus suppress various warnings. */

#define EMIT_ASM(NAME,INSNS) \
{ extern unsigned char start_ ## NAME, end_ ## NAME; \
add_insns (&start_ ## NAME, &end_ ## NAME - &start_ ## NAME); \
if (always_true ()) \
goto skipover ## NAME; \
__asm__ ("start_" #NAME ":\n\t" INSNS "\n\tend_" #NAME ":\n\t"); \
skipover ## NAME: \
; }