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2010-06-20 Ian Lance Taylor <iant@google.com> 

Pedro Alves  <pedro@codesourcery.com>

	* linux-x86-low.c (always_true): Delete.
	(EMIT_ASM, EMIT_ASM32): Use an uncondition asm jmp instead of
	trying to fool the compiler with always_true.
This commit is contained in:
Pedro Alves 2010-06-20 22:23:36 +00:00
parent c6beb2cba6
commit 9e4344e5ea
2 changed files with 28 additions and 25 deletions
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7
gdb/gdbserver/ChangeLog
View File

@ -1,3 +1,10 @@
2010-06-20 Ian Lance Taylor <iant@google.com>
Pedro Alves <pedro@codesourcery.com>
* linux-x86-low.c (always_true): Delete.
(EMIT_ASM, EMIT_ASM32): Use an uncondition asm jmp instead of
trying to fool the compiler with always_true.
2010-06-20 Pedro Alves <pedro@codesourcery.com>
* tracepoint.c (condition_true_at_tracepoint): Don't run compiled

46
gdb/gdbserver/linux-x86-low.c
View File

@ -1484,41 +1484,37 @@ add_insns (unsigned char *start, int len)
current_insn_ptr = buildaddr;
}
/* A function used to trick optimizers. */
int
always_true (void)
{
return 1;
}
/* 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: \
; }
#define EMIT_ASM(NAME, INSNS) \
do \
{ \
extern unsigned char start_ ## NAME, end_ ## NAME; \
add_insns (&start_ ## NAME, &end_ ## NAME - &start_ ## NAME); \
__asm__ ("jmp end_" #NAME "\n" \
"\t" "start_" #NAME ":" \
"\t" INSNS "\n" \
"\t" "end_" #NAME ":"); \
} while (0)
#ifdef __x86_64__
#define EMIT_ASM32(NAME,INSNS) \
{ extern unsigned char start_ ## NAME, end_ ## NAME; \
add_insns (&start_ ## NAME, &end_ ## NAME - &start_ ## NAME); \
if (always_true ()) \
goto skipover ## NAME; \
__asm__ (".code32\n\tstart_" #NAME ":\n\t" INSNS "\n\tend_" #NAME ":\n" \
"\t.code64\n\t"); \
skipover ## NAME: \
; }
do \
{ \
extern unsigned char start_ ## NAME, end_ ## NAME; \
add_insns (&start_ ## NAME, &end_ ## NAME - &start_ ## NAME); \
__asm__ (".code32\n" \
"\t" "jmp end_" #NAME "\n" \
"\t" "start_" #NAME ":\n" \
"\t" INSNS "\n" \
"\t" "end_" #NAME ":\n" \
".code64\n"); \
} while (0)
#else