Richard Henderson <r...@twiddle.net> writes:
> This allows an output operand to match an input operand
> only when the input operand needs a register.
>
> Signed-off-by: Richard Henderson <r...@twiddle.net>
It's hard to offer anything more than a mechanical review for this as
the constraints aren't intuitive to me (I guess not as a gcc hacker!).
Could we either expand the documentation of constraints in tcg/README
with a summary of the global ones?
Should there be a one to one mapping of textual constraint descriptions
to the TCG_CT_FOO defines? I'm finding it hard to figure out why the
text->bitfield step is needed. Is it something to do with the merging of
generic TCG op constraints with their backend counterparts?
Anyway:
Reviewed-by: Alex Bennée <alex.ben...@linaro.org>
> ---
> tcg/tcg.c | 63
> ++++++++++++++++++++++++++++++++-------------------------------
> 1 file changed, 32 insertions(+), 31 deletions(-)
>
> diff --git a/tcg/tcg.c b/tcg/tcg.c
> index 8b4dce7..cb898f1 100644
> --- a/tcg/tcg.c
> +++ b/tcg/tcg.c
> @@ -1256,37 +1256,37 @@ static void process_op_defs(TCGContext *s)
>
> tcg_regset_clear(def->args_ct[i].u.regs);
> def->args_ct[i].ct = 0;
> - if (ct_str[0] >= '0' && ct_str[0] <= '9') {
> - int oarg;
> - oarg = ct_str[0] - '0';
> - tcg_debug_assert(oarg < def->nb_oargs);
> - tcg_debug_assert(def->args_ct[oarg].ct & TCG_CT_REG);
> - /* TCG_CT_ALIAS is for the output arguments. The input
> - argument is tagged with TCG_CT_IALIAS. */
> - def->args_ct[i] = def->args_ct[oarg];
> - def->args_ct[oarg].ct = TCG_CT_ALIAS;
> - def->args_ct[oarg].alias_index = i;
> - def->args_ct[i].ct |= TCG_CT_IALIAS;
> - def->args_ct[i].alias_index = oarg;
> - } else {
> - for(;;) {
> - if (*ct_str == '\0')
> - break;
> - switch(*ct_str) {
> - case '&':
> - def->args_ct[i].ct |= TCG_CT_NEWREG;
> - ct_str++;
> - break;
> - case 'i':
> - def->args_ct[i].ct |= TCG_CT_CONST;
> - ct_str++;
> - break;
> - default:
> - ct_str = target_parse_constraint(&def->args_ct[i],
> - ct_str, type);
> - /* Typo in TCGTargetOpDef constraint. */
> - tcg_debug_assert(ct_str != NULL);
> + while (*ct_str != '\0') {
> + switch(*ct_str) {
> + case '0' ... '9':
> + {
> + int oarg = *ct_str - '0';
> + tcg_debug_assert(ct_str == tdefs->args_ct_str[i]);
> + tcg_debug_assert(oarg < def->nb_oargs);
> + tcg_debug_assert(def->args_ct[oarg].ct & TCG_CT_REG);
> + /* TCG_CT_ALIAS is for the output arguments.
> + The input is tagged with TCG_CT_IALIAS. */
> + def->args_ct[i] = def->args_ct[oarg];
> + def->args_ct[oarg].ct |= TCG_CT_ALIAS;
> + def->args_ct[oarg].alias_index = i;
> + def->args_ct[i].ct |= TCG_CT_IALIAS;
> + def->args_ct[i].alias_index = oarg;
> }
> + ct_str++;
> + break;
> + case '&':
> + def->args_ct[i].ct |= TCG_CT_NEWREG;
> + ct_str++;
> + break;
> + case 'i':
> + def->args_ct[i].ct |= TCG_CT_CONST;
> + ct_str++;
> + break;
> + default:
> + ct_str = target_parse_constraint(&def->args_ct[i],
> + ct_str, type);
> + /* Typo in TCGTargetOpDef constraint. */
> + tcg_debug_assert(ct_str != NULL);
> }
> }
> }
> @@ -2296,7 +2296,8 @@ static void tcg_reg_alloc_op(TCGContext *s,
> arg = args[i];
> arg_ct = &def->args_ct[i];
> ts = &s->temps[arg];
> - if (arg_ct->ct & TCG_CT_ALIAS) {
> + if ((arg_ct->ct & TCG_CT_ALIAS)
> + && !const_args[arg_ct->alias_index]) {
> reg = new_args[arg_ct->alias_index];
> } else if (arg_ct->ct & TCG_CT_NEWREG) {
> reg = tcg_reg_alloc(s, arg_ct->u.regs,
--
Alex Bennée
