On Thu, 23 May 2002, Aldo Calpini wrote:
> hello people,
>
> I've implemented some print opcodes in JIT (for i386), but I would
> like to know your opinion about these before submitting a patch.
>
> in reality, there isn't a big performance boost, because I'm just
> calling printf as the C opcode does. it just saves some
> push/pop/call/ret instructions. the advantage is that such hack is
> portable across platform. implementing a more low-level print
> mechanism (involving system calls probably) would require several
> #ifdef..#endif, I suppose.
>
> anyway, this implements a new function in jit_emit.h which makes
> a call to a C function (an absolute address, that is). this is the
> function I've added to jit_emit.h:
>
> void emit_call_abs(Parrot_jit_info *jit_info,
> long absaddr, int putback)
> {
> Parrot_jit_newfixup(jit_info);
> jit_info->fixups->type = JIT_X86CALL;
> jit_info->fixups->param.fptr = (void (*)(void)) absaddr;
>
> emitm_calll(jit_info->native_ptr, 0xdeafc0de);
> emitm_addl_i_r(jit_info->native_ptr, putback, emit_ESP);
> }
>
> this is very similar to Parrot_jit_normal_op, except that the
> address is stored 'as it is' and the bytes to be added to ESP are
> variable.
>
> and this is how print_ic is implemented in core.jit:
>
> Parrot_print_ic {
> emitm_pushl_i(NATIVECODE, *INT_CONST[1]);
> emitm_pushl_i(NATIVECODE, (long) INTVAL_FMT);
> emit_call_abs(jit_info, (long) printf, 8);
> }
>
> print_nc looks like this (I needed to define a private long because
> simply saying (&NUM_CONST[1])+4 doesn't work):
>
> Parrot_print_nc {
> long mydouble = (long) &NUM_CONST[1];
> NATIVECODE = emit_pushl_m(NATIVECODE, emit_None, emit_None,
> emit_None, mydouble+4);
> NATIVECODE = emit_pushl_m(NATIVECODE, emit_None, emit_None,
> emit_None, mydouble);
> emitm_pushl_i(NATIVECODE, (long) FLOATVAL_FMT);
> emit_call_abs(jit_info, (long) printf, 12);
> }
>
> also print_sc is similar, except that there isn't a STRINGVAL_FMT
> defined in config.h:
>
> Parrot_print_sc {
> NATIVECODE = emit_pushl_m(NATIVECODE, emit_None, emit_None,
> emit_None, (long) &STRING_CONST[1]->bufstart);
> emitm_pushl_i(NATIVECODE, (long) "%s");
> emit_call_abs(jit_info, (long) printf, 8);
> }
Don't implement any print op yet, if I didn't understood wrong they are
going to be updated to use the IO system.
>
> another little thing I've done, but I'm not sure if there's need
> for this, is having added these lines to jit.c in the build_asm
> routine, just before returning:
>
> if (Interp_flags_TEST(interpreter, PARROT_DEBUG_FLAG)) {
> fprintf(stderr, "*** Parrot VM: JITted code at 0x%08x. ***\n",
> jit_info.arena_start);
> }
>
> this way when I start 'parrot -j -d something' it tells me where
> to find the JIT, and I can goto there directly in the debugger.
> it's really a time saver for me.
The -d flag will be use for the parrot debugger, Can't you stop your
debugger at runops_jit?
Daniel Grunblatt.
