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Re: [PATCH 2/2] gcc/genrecog: Don't warn for missing mode on special predicates


* Richard Sandiford <richard.sandiford@arm.com> [2016-07-04 09:47:20 +0100]:

> Andrew Burgess <andrew.burgess@embecosm.com> writes:
> > +/* Return true if OPERAND is a MATCH_OPERAND using a special predicate
> > +   function.  */
> > +
> > +static bool
> > +special_predicate_operand_p (rtx operand)
> > +{
> > +  if (GET_CODE (operand) == MATCH_OPERAND)
> > +    {
> > +      const char *pred_name = predicate_name (operand);
> > +      if (pred_name[0] != 0)
> > +	{
> > +	  const struct pred_data *pred;
> > +
> > +	  pred = lookup_predicate (pred_name);
> > +	  return pred->special;
> 
> Thanks for removing the duplicated error check for unknown predicates.
> I think that error gets reported later though, so we should check for
> null here:
> 
>       return pred && pred->special;
> 
> OK with that change, thanks.

Richard,

Thanks for the continued reviews.  I don't have GCC write access, so I
wonder if you would be willing to commit this patch for me please.

There's an updated version below that includes the latest change you
suggested.

Many thanks,
Andrew

---

[PATCH] gcc/genrecog: Don't warn for missing mode on special predicates

In md.texi it says:

  Predicates written with @code{define_special_predicate} do not get any
  automatic mode checks, and are treated as having special mode handling
  by @command{genrecog}.

In genrecog, when validating a SET pattern, there is already a special
case for 'address_operand' which is a special predicate, however,
other special predicates fall through to the code which checks for
incorrect use of VOIDmode.

This commit adds a new function for detecting special predicates, and
then generalises the check in validate_pattern so that mode checking
is skipped for all special predicates.

gcc/ChangeLog:

	* genrecog.c (special_predicate_operand_p): New function.
	(predicate_name): Move function.
	(validate_pattern): Don't warn about missing mode for all
	define_special_predicate predicates.
---
 gcc/ChangeLog  |  7 +++++++
 gcc/genrecog.c | 50 +++++++++++++++++++++++++++++++++++---------------
 2 files changed, 42 insertions(+), 15 deletions(-)

diff --git a/gcc/genrecog.c b/gcc/genrecog.c
index a9f5a4a..056798c 100644
--- a/gcc/genrecog.c
+++ b/gcc/genrecog.c
@@ -463,6 +463,38 @@ constraints_supported_in_insn_p (rtx insn)
 	   || GET_CODE (insn) == DEFINE_PEEPHOLE2);
 }
 
+/* Return the name of the predicate matched by MATCH_RTX.  */
+
+static const char *
+predicate_name (rtx match_rtx)
+{
+  if (GET_CODE (match_rtx) == MATCH_SCRATCH)
+    return "scratch_operand";
+  else
+    return XSTR (match_rtx, 1);
+}
+
+/* Return true if OPERAND is a MATCH_OPERAND using a special predicate
+   function.  */
+
+static bool
+special_predicate_operand_p (rtx operand)
+{
+  if (GET_CODE (operand) == MATCH_OPERAND)
+    {
+      const char *pred_name = predicate_name (operand);
+      if (pred_name[0] != 0)
+	{
+	  const struct pred_data *pred;
+
+	  pred = lookup_predicate (pred_name);
+	  return pred != NULL && pred->special;
+	}
+    }
+
+  return false;
+}
+
 /* Check for various errors in PATTERN, which is part of INFO.
    SET is nonnull for a destination, and is the complete set pattern.
    SET_CODE is '=' for normal sets, and '+' within a context that
@@ -651,10 +683,9 @@ validate_pattern (rtx pattern, md_rtx_info *info, rtx set, int set_code)
 	dmode = GET_MODE (dest);
 	smode = GET_MODE (src);
 
-	/* The mode of an ADDRESS_OPERAND is the mode of the memory
-	   reference, not the mode of the address.  */
-	if (GET_CODE (src) == MATCH_OPERAND
-	    && ! strcmp (XSTR (src, 1), "address_operand"))
+	/* Mode checking is not performed for special predicates.  */
+	if (special_predicate_operand_p (src)
+	    || special_predicate_operand_p (dest))
 	  ;
 
         /* The operands of a SET must have the same mode unless one
@@ -3788,17 +3819,6 @@ operator < (const pattern_pos &e1, const pattern_pos &e2)
   return diff < 0;
 }
 
-/* Return the name of the predicate matched by MATCH_RTX.  */
-
-static const char *
-predicate_name (rtx match_rtx)
-{
-  if (GET_CODE (match_rtx) == MATCH_SCRATCH)
-    return "scratch_operand";
-  else
-    return XSTR (match_rtx, 1);
-}
-
 /* Add new decisions to S that check whether the rtx at position POS
    matches PATTERN.  Return the state that is reached in that case.
    TOP_PATTERN is the overall pattern, as passed to match_pattern_1.  */
-- 
2.5.1


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