[DTrace-devel] [PATCH 5/7] cg: optional 4th arg for dt_cg_subr_arg_to_tstring() calls

[Eugene Loh]

Reviewed-by: Eugene Loh <eugene.loh at oracle.com>

The subject line threw me for a while:  it looked like 5th and 6th args 
to dt_cg_subr_arg_to_tstring(), but now I see what you mean. Okay.

Also, ISIGN looks to me like I SIGN. Might you consider IGNOR?  Might 
make more sense especially since in this case there is nothing to "is".

On 7/27/23 11:30, Kris Van Hees via DTrace-devel wrote:
> Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> ---
>   libdtrace/dt_cg.c | 26 +++++++++++++++++---------
>   1 file changed, 17 insertions(+), 9 deletions(-)
>
> diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
> index 6a1413f0..e05a1f64 100644
> --- a/libdtrace/dt_cg.c
> +++ b/libdtrace/dt_cg.c
> @@ -24,6 +24,7 @@
>   #include <dt_string.h>
>   #include <bpf_asm.h>
>   
> +#define DT_ISIGN	-1		/* Ignore the value */
>   #define DT_ISIMM	0
>   #define DT_ISREG	1
>   
> @@ -976,7 +977,7 @@ dt_cg_probe_error(dt_pcb_t *pcb, uint32_t fault, int illisreg, uint64_t ill)
>   	 * one we are about to blindly reuse.
>   	 */
>   
> -	if (illisreg && ill != 4)
> +	if (illisreg == DT_ISREG && ill != 4)
>   		emit(dlp, BPF_MOV_REG(BPF_REG_4, ill));
>   	else
>   		emit(dlp, BPF_MOV_IMM(BPF_REG_4, ill));
> @@ -1213,7 +1214,7 @@ dt_cg_alloca_access_check(dt_irlist_t *dlp, dt_regset_t *drp, int reg,
>   	emitl(dlp, lbl_base_ok,
>   		   BPF_NOP());
>   
> -	if (isreg)
> +	if (isreg == DT_ISREG)
>   		emit(dlp, BPF_ALU64_REG(BPF_SUB, BPF_REG_0, size));
>   	else
>   		emit(dlp, BPF_ALU64_IMM(BPF_SUB, BPF_REG_0, size));
> @@ -2563,7 +2564,8 @@ dt_cg_ldsize(dt_node_t *dnp, ctf_file_t *ctfp, ctf_id_t type, ssize_t *ret_size)
>   	 * rounding cte_bits up to a byte boundary and then finding the
>   	 * nearest power of two to this value (see clp2(), above).
>   	 */
> -	if ((dnp->dn_flags & DT_NF_BITFIELD) &&
> +	if (dnp &&
> +	    (dnp->dn_flags & DT_NF_BITFIELD) &&
>   	    ctf_type_encoding(ctfp, type, &e) != CTF_ERR)
>   		size = clp2(P2ROUNDUP(e.cte_bits, NBBY) / NBBY);
>   	else
> @@ -4578,14 +4580,15 @@ dt_cg_array_op(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
>   
>   /*
>    * Emit code to call a precompiled BPF function (named by fname)
> - * that is of return type void and takes three arguments:
> + * that is of return type void and takes three or four arguments:
>    *   - a pointer to the DTrace context (dctx)
>    *   - one input value
>    *   - a pointer to an output tstring, allocated here
> + *   - an optional uint32_t value
>    */
>   static void
>   dt_cg_subr_arg_to_tstring(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp,
> -			   const char *fname)
> +			  const char *fname, int isreg, uint32_t val)
>   {
>   	dt_ident_t	*idp;
>   	dt_node_t	*arg = dnp->dn_args;
> @@ -4619,6 +4622,11 @@ dt_cg_subr_arg_to_tstring(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp,
>   
>   	emit(dlp,  BPF_MOV_REG(BPF_REG_3, dnp->dn_reg));
>   
> +	if (isreg == DT_ISREG)
> +		emit(dlp, BPF_MOV_REG(BPF_REG_4, val));
> +	else if (isreg == DT_ISIMM)
> +		emit(dlp, BPF_MOV_IMM(BPF_REG_4, val));
> +
>   	idp = dt_dlib_get_func(yypcb->pcb_hdl, fname);
>   	assert(idp != NULL);
>   	dt_regset_xalloc(drp, BPF_REG_0);
> @@ -4632,13 +4640,13 @@ dt_cg_subr_arg_to_tstring(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp,
>   static void
>   dt_cg_subr_basename(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
>   {
> -	dt_cg_subr_arg_to_tstring(dnp, dlp, drp, "dt_basename");
> +	dt_cg_subr_arg_to_tstring(dnp, dlp, drp, "dt_basename", DT_ISIGN, 0);
>   }
>   
>   static void
>   dt_cg_subr_dirname(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
>   {
> -	dt_cg_subr_arg_to_tstring(dnp, dlp, drp, "dt_dirname");
> +	dt_cg_subr_arg_to_tstring(dnp, dlp, drp, "dt_dirname", DT_ISIGN, 0);
>   }
>   
>   static void
> @@ -4703,7 +4711,7 @@ dt_cg_subr_index(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
>   static void
>   dt_cg_subr_lltostr(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
>   {
> -	dt_cg_subr_arg_to_tstring(dnp, dlp, drp, "dt_lltostr");
> +	dt_cg_subr_arg_to_tstring(dnp, dlp, drp, "dt_lltostr", DT_ISIGN, 0);
>   }
>   
>   static void
> @@ -5867,7 +5875,7 @@ dt_cg_subr_htonll(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
>   static void
>   dt_cg_subr_inet_ntoa(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
>   {
> -	dt_cg_subr_arg_to_tstring(dnp, dlp, drp, "dt_inet_ntoa");
> +	dt_cg_subr_arg_to_tstring(dnp, dlp, drp, "dt_inet_ntoa", DT_ISIGN, 0);
>   }
>   
>   typedef void dt_cg_subr_f(dt_node_t *, dt_irlist_t *, dt_regset_t *);