diff mbox

[RFC] Handle sequence in reg_set_p

Message ID 1420719782.2473.122.camel@yam-132-YW-E178-FTW
State New
Headers show

Commit Message

Oleg Endo Jan. 8, 2015, 12:23 p.m. UTC 
Hi,

Currently reg_set_p doesn't handle sequence rtx, which I've identified
as the root cause of PR 64479.  There is another alternative fix for the
PR, but I'd like to get some comments regarding letting reg_set_p also
handle sequence rtx:


Would that be OK to do if it passes testing, or is there something that
could potentially/obviously blow up?

Cheers,
Oleg

Comments

Jeff Law Jan. 8, 2015, 9:18 p.m. UTC | #1 
On 01/08/15 05:23, Oleg Endo wrote:
> Hi,
>
> Currently reg_set_p doesn't handle sequence rtx, which I've identified
> as the root cause of PR 64479.  There is another alternative fix for the
> PR, but I'd like to get some comments regarding letting reg_set_p also
> handle sequence rtx:
>
> Index: gcc/rtlanal.c
> ===================================================================
> --- gcc/rtlanal.c	(revision 218544)
> +++ gcc/rtlanal.c	(working copy)
> @@ -875,17 +875,24 @@
>   {
>     /* We can be passed an insn or part of one.  If we are passed an insn,
>        check if a side-effect of the insn clobbers REG.  */
> -  if (INSN_P (insn)
> -      && (FIND_REG_INC_NOTE (insn, reg)
> -	  || (CALL_P (insn)
> -	      && ((REG_P (reg)
> -		   && REGNO (reg) < FIRST_PSEUDO_REGISTER
> -		   && overlaps_hard_reg_set_p (regs_invalidated_by_call,
> -					       GET_MODE (reg), REGNO (reg)))
> -		  || MEM_P (reg)
> -		  || find_reg_fusage (insn, CLOBBER, reg)))))
> -    return 1;
> +  if (INSN_P (insn) && FIND_REG_INC_NOTE (insn, reg))
> +    return true;
>
> +  /* After delay slot handling, call and branch insns might be in a
> +     sequence.  Check all the elements there.  */
> +  if (INSN_P (insn) && GET_CODE (PATTERN (insn)) == SEQUENCE)
> +    for (int i = 0; i < XVECLEN (PATTERN (insn), 0); ++i)
> +      if (reg_set_p (reg, XVECEXP (PATTERN (insn), 0, i)))
> +	return true;
> +
> +  if (CALL_P (insn)
> +      && ((REG_P (reg) && REGNO (reg) < FIRST_PSEUDO_REGISTER
> +	   && overlaps_hard_reg_set_p (regs_invalidated_by_call,
> +				       GET_MODE (reg), REGNO (reg)))
> +	  || MEM_P (reg)
> +	  || find_reg_fusage (insn, CLOBBER, reg)))
> +	return true;
> +
>     return set_of (reg, insn) != NULL_RTX;
>   }
>
>
> Would that be OK to do if it passes testing, or is there something that
> could potentially/obviously blow up?
It looks reasonable to me.

Any particular reason why the SEQUENCE handling isn't done first, then 
the REG_INC and CALL insn handling?  I'd probably explicitly return 
false if we had a sequence and none of its elements returned true. 
There's no need to check anything on the toplevel SEQUENCE to the best 
of my knowledge.

jeff
diff mbox

Patch

Index: gcc/rtlanal.c
===================================================================
--- gcc/rtlanal.c	(revision 218544)
+++ gcc/rtlanal.c	(working copy)
@@ -875,17 +875,24 @@ 
 {
   /* We can be passed an insn or part of one.  If we are passed an insn,
      check if a side-effect of the insn clobbers REG.  */
-  if (INSN_P (insn)
-      && (FIND_REG_INC_NOTE (insn, reg)
-	  || (CALL_P (insn)
-	      && ((REG_P (reg)
-		   && REGNO (reg) < FIRST_PSEUDO_REGISTER
-		   && overlaps_hard_reg_set_p (regs_invalidated_by_call,
-					       GET_MODE (reg), REGNO (reg)))
-		  || MEM_P (reg)
-		  || find_reg_fusage (insn, CLOBBER, reg)))))
-    return 1;
+  if (INSN_P (insn) && FIND_REG_INC_NOTE (insn, reg))
+    return true;
 
+  /* After delay slot handling, call and branch insns might be in a
+     sequence.  Check all the elements there.  */
+  if (INSN_P (insn) && GET_CODE (PATTERN (insn)) == SEQUENCE)
+    for (int i = 0; i < XVECLEN (PATTERN (insn), 0); ++i)
+      if (reg_set_p (reg, XVECEXP (PATTERN (insn), 0, i)))
+	return true;
+
+  if (CALL_P (insn)
+      && ((REG_P (reg) && REGNO (reg) < FIRST_PSEUDO_REGISTER
+	   && overlaps_hard_reg_set_p (regs_invalidated_by_call,
+				       GET_MODE (reg), REGNO (reg)))
+	  || MEM_P (reg)
+	  || find_reg_fusage (insn, CLOBBER, reg)))
+	return true;
+
   return set_of (reg, insn) != NULL_RTX;
 }