Hi Eric,
Sorry for the delay, for some reasons despite being a recipient the mail
didn't hit my inbox but only my gcc-patches box.
> From: gcc-patches-ow...@gcc.gnu.org [mailto:gcc-patches-
> ow...@gcc.gnu.org] On Behalf Of Eric Botcazou
>
> > 2014-11-14 Thomas Preud'homme
> >
> > * regrename.c (find_best_rename_reg): Rename to ...
> > (find_rename_reg): This. Also add a parameter to skip tick check.
> > * regrename.h: Likewise.
> > * config/c6x/c6x.c: Adapt to above renaming.
>
> Missing function in config/c6x/c6x.c entry.
Here is the proposed ChangeLog entry:
2014-11-26 Thomas Preud'homme thomas.preudho...@arm.com\
* regrename.c (find_best_rename_reg): Rename to ...
(find_rename_reg): This. Also add a parameter to skip tick check.
* regrename.h: Likewise.
* config/c6x/c6x.c (try_rename_operands): Adapt to above renaming.
>
> Please write it like so:
>
> if (!check_new_reg_p (old_reg, new_reg, this_head,
> *unavailable))
> continue;
>
> if (!best_rename)
> return new_reg;
>
> /* In the first pass, we force the renaming of registers that
>don't belong to PREFERRED_CLASS to registers that do, even
>though the latters were used not very long ago. *
> if ((pass == 0
>&& !TEST_HARD_REG_BIT
> (reg_class_contents[preferred_class],
> best_new_reg))
> || tick[best_new_reg] > tick[new_reg]))
> best_new_reg = new_reg;
Oh yes, much better indeed. I should have thought about this. Please find below
the patch reworked as above.
diff --git a/gcc/config/c6x/c6x.c b/gcc/config/c6x/c6x.c
index 06319d0..6aca1e3 100644
--- a/gcc/config/c6x/c6x.c
+++ b/gcc/config/c6x/c6x.c
@@ -3513,7 +3513,8 @@ try_rename_operands (rtx_insn *head, rtx_insn *tail,
unit_req_table reqs,
COMPL_HARD_REG_SET (unavailable, reg_class_contents[(int) super_class]);
old_reg = this_head->regno;
- best_reg = find_best_rename_reg (this_head, super_class, &unavailable,
old_reg);
+ best_reg = find_rename_reg (this_head, super_class, &unavailable, old_reg,
+ true);
regrename_do_replace (this_head, best_reg);
diff --git a/gcc/regrename.h b/gcc/regrename.h
index 03b7164..05c78ad 100644
--- a/gcc/regrename.h
+++ b/gcc/regrename.h
@@ -89,8 +89,8 @@ extern void regrename_init (bool);
extern void regrename_finish (void);
extern void regrename_analyze (bitmap);
extern du_head_p regrename_chain_from_id (unsigned int);
-extern int find_best_rename_reg (du_head_p, enum reg_class, HARD_REG_SET *,
-int);
+extern int find_rename_reg (du_head_p, enum reg_class, HARD_REG_SET *, int,
+ bool);
extern void regrename_do_replace (du_head_p, int);
#endif
diff --git a/gcc/regrename.c b/gcc/regrename.c
index 66f562b..88321d0 100644
--- a/gcc/regrename.c
+++ b/gcc/regrename.c
@@ -357,11 +357,13 @@ check_new_reg_p (int reg ATTRIBUTE_UNUSED, int new_reg,
/* For the chain THIS_HEAD, compute and return the best register to
rename to. SUPER_CLASS is the superunion of register classes in
the chain. UNAVAILABLE is a set of registers that cannot be used.
- OLD_REG is the register currently used for the chain. */
+ OLD_REG is the register currently used for the chain. BEST_RENAME
+ controls whether the register chosen must be better than the
+ current one or just respect the given constraint. */
int
-find_best_rename_reg (du_head_p this_head, enum reg_class super_class,
- HARD_REG_SET *unavailable, int old_reg)
+find_rename_reg (du_head_p this_head, enum reg_class super_class,
+HARD_REG_SET *unavailable, int old_reg, bool best_rename)
{
bool has_preferred_class;
enum reg_class preferred_class;
@@ -400,15 +402,19 @@ find_best_rename_reg (du_head_p this_head, enum reg_class
super_class,
new_reg))
continue;
+ if (!check_new_reg_p (old_reg, new_reg, this_head, *unavailable))
+ continue;
+
+ if (!best_rename)
+ return new_reg;
+
/* In the first pass, we force the renaming of registers that
don't belong to PREFERRED_CLASS to registers that do, even
though the latters were used not very long ago. */
- if (check_new_reg_p (old_reg, new_reg, this_head,
- *unavailable)
- && ((pass == 0
- && !TEST_HARD_REG_BIT (reg_class_contents[preferred_class],
- best_new_reg))
- || tick[best_new_reg] > tick[new_reg]))
+ if ((pass == 0
+ && !TEST_HARD_REG_BIT (reg_class_contents[preferred_class],
+best_new_reg))
+ || tick[best_new_reg] > tick[new_reg])
best_new_reg = new_reg;
}
if (pass == 0 &
