combine.c (subst): Process the inputs to a parallel asm_operands only once.

        * combine.c (subst): Process the inputs to a parallel asm_operands
        only once.

From-SVN: r23357

2 files changed, 139 insertions, 83 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f7265a6..f675520 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+Mon Oct 26 13:35:02 1998  Richard Henderson  <rth@cygnus.com>
+
+	* combine.c (subst): Process the inputs to a parallel asm_operands
+	only once.
+
 Mon Oct 26 13:32:31 1998  Richard Henderson  <rth@cygnus.com>
 
 	* stmt.c (expand_asm_operands): Accept `=' or `+' at any position.
diff --git a/gcc/combine.c b/gcc/combine.c
index 88cc6c5..4094561 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -3048,103 +3048,154 @@ subst (x, from, to, in_dest, unique_copy)
   if (COMBINE_RTX_EQUAL_P (x, to))
     return to;
 
-  len = GET_RTX_LENGTH (code);
-  fmt = GET_RTX_FORMAT (code);
+  /* Parallel asm_operands need special attention because all of the
+     inputs are shared across the arms.  Furthermore, unsharing the
+     rtl results in recognition failures.  Failure to handle this case
+     specially can result in circular rtl.
+
+     Solve this by doing a normal pass across the first entry of the
+     parallel, and only processing the SET_DESTs of the subsequent
+     entries.  Ug.  */
+
+  if (code == PARALLEL
+      && GET_CODE (XVECEXP (x, 0, 0)) == SET
+      && GET_CODE (SET_SRC (XVECEXP (x, 0, 0))) == ASM_OPERANDS)
+    {
+      new = subst (XVECEXP (x, 0, 0), from, to, 0, unique_copy);
 
-  /* We don't need to process a SET_DEST that is a register, CC0, or PC, so
-     set up to skip this common case.  All other cases where we want to
-     suppress replacing something inside a SET_SRC are handled via the
-     IN_DEST operand.  */
-  if (code == SET
-      && (GET_CODE (SET_DEST (x)) == REG
-        || GET_CODE (SET_DEST (x)) == CC0
-        || GET_CODE (SET_DEST (x)) == PC))
-    fmt = "ie";
-
-  /* Get the mode of operand 0 in case X is now a SIGN_EXTEND of a
-     constant.  */
-  if (fmt[0] == 'e')
-    op0_mode = GET_MODE (XEXP (x, 0));
+      /* If this substitution failed, this whole thing fails.  */
+      if (GET_CODE (new) == CLOBBER
+	  && XEXP (new, 0) == const0_rtx)
+	return new;
 
-  for (i = 0; i < len; i++)
-    {
-      if (fmt[i] == 'E')
+      SUBST (XVECEXP (x, 0, 0), new);
+
+      for (i = XVECLEN (x, 0) - 1; i >= 1; i--)
 	{
-	  register int j;
-	  for (j = XVECLEN (x, i) - 1; j >= 0; j--)
+	  rtx dest = SET_DEST (XVECEXP (x, 0, i));
+	  
+	  if (GET_CODE (dest) != REG
+	      && GET_CODE (dest) != CC0
+	      && GET_CODE (dest) != PC)
 	    {
-	      if (COMBINE_RTX_EQUAL_P (XVECEXP (x, i, j), from))
-		{
-		  new = (unique_copy && n_occurrences ? copy_rtx (to) : to);
-		  n_occurrences++;
-		}
-	      else
-		{
-		  new = subst (XVECEXP (x, i, j), from, to, 0, unique_copy);
+	      new = subst (dest, from, to, 0, unique_copy);
 
-		  /* If this substitution failed, this whole thing fails.  */
-		  if (GET_CODE (new) == CLOBBER && XEXP (new, 0) == const0_rtx)
-		    return new;
-		}
+	      /* If this substitution failed, this whole thing fails.  */
+	      if (GET_CODE (new) == CLOBBER
+		  && XEXP (new, 0) == const0_rtx)
+		return new;
 
-	      SUBST (XVECEXP (x, i, j), new);
+	      SUBST (SET_DEST (XVECEXP (x, 0, i)), new);
 	    }
 	}
-      else if (fmt[i] == 'e')
+    }
+  else
+    {
+      len = GET_RTX_LENGTH (code);
+      fmt = GET_RTX_FORMAT (code);
+
+      /* We don't need to process a SET_DEST that is a register, CC0,
+	 or PC, so set up to skip this common case.  All other cases
+	 where we want to suppress replacing something inside a
+	 SET_SRC are handled via the IN_DEST operand.  */
+      if (code == SET
+	  && (GET_CODE (SET_DEST (x)) == REG
+	      || GET_CODE (SET_DEST (x)) == CC0
+	      || GET_CODE (SET_DEST (x)) == PC))
+	fmt = "ie";
+
+      /* Get the mode of operand 0 in case X is now a SIGN_EXTEND of a
+	 constant.  */
+      if (fmt[0] == 'e')
+	op0_mode = GET_MODE (XEXP (x, 0));
+
+      for (i = 0; i < len; i++)
 	{
-	  if (COMBINE_RTX_EQUAL_P (XEXP (x, i), from))
+	  if (fmt[i] == 'E')
+	    {
+	      register int j;
+	      for (j = XVECLEN (x, i) - 1; j >= 0; j--)
+		{
+		  if (COMBINE_RTX_EQUAL_P (XVECEXP (x, i, j), from))
+		    {
+		      new = (unique_copy && n_occurrences
+			     ? copy_rtx (to) : to);
+		      n_occurrences++;
+		    }
+		  else
+		    {
+		      new = subst (XVECEXP (x, i, j), from, to, 0,
+				   unique_copy);
+
+		      /* If this substitution failed, this whole thing
+			 fails.  */
+		      if (GET_CODE (new) == CLOBBER
+			  && XEXP (new, 0) == const0_rtx)
+			return new;
+		    }
+
+		  SUBST (XVECEXP (x, i, j), new);
+		}
+	    }
+	  else if (fmt[i] == 'e')
 	    {
-	      /* In general, don't install a subreg involving two modes not
-		 tieable.  It can worsen register allocation, and can even
-		 make invalid reload insns, since the reg inside may need to
-		 be copied from in the outside mode, and that may be invalid
-		 if it is an fp reg copied in integer mode.
-
-		 We allow two exceptions to this: It is valid if it is inside
-		 another SUBREG and the mode of that SUBREG and the mode of
-		 the inside of TO is tieable and it is valid if X is a SET
-		 that copies FROM to CC0.  */
-	      if (GET_CODE (to) == SUBREG
-		  && ! MODES_TIEABLE_P (GET_MODE (to),
-					GET_MODE (SUBREG_REG (to)))
-		  && ! (code == SUBREG
-			&& MODES_TIEABLE_P (GET_MODE (x),
-					    GET_MODE (SUBREG_REG (to))))
+	      if (COMBINE_RTX_EQUAL_P (XEXP (x, i), from))
+		{
+		  /* In general, don't install a subreg involving two
+		     modes not tieable.  It can worsen register
+		     allocation, and can even make invalid reload
+		     insns, since the reg inside may need to be copied
+		     from in the outside mode, and that may be invalid
+		     if it is an fp reg copied in integer mode.
+
+		     We allow two exceptions to this: It is valid if
+		     it is inside another SUBREG and the mode of that
+		     SUBREG and the mode of the inside of TO is
+		     tieable and it is valid if X is a SET that copies
+		     FROM to CC0.  */
+
+		  if (GET_CODE (to) == SUBREG
+		      && ! MODES_TIEABLE_P (GET_MODE (to),
+					    GET_MODE (SUBREG_REG (to)))
+		      && ! (code == SUBREG
+			    && MODES_TIEABLE_P (GET_MODE (x),
+						GET_MODE (SUBREG_REG (to))))
 #ifdef HAVE_cc0
-		  && ! (code == SET && i == 1 && XEXP (x, 0) == cc0_rtx)
+		      && ! (code == SET && i == 1 && XEXP (x, 0) == cc0_rtx)
 #endif
-		  )
-		return gen_rtx_CLOBBER (VOIDmode, const0_rtx);
+		      )
+		    return gen_rtx_CLOBBER (VOIDmode, const0_rtx);
 
-	      new = (unique_copy && n_occurrences ? copy_rtx (to) : to);
-	      n_occurrences++;
+		  new = (unique_copy && n_occurrences ? copy_rtx (to) : to);
+		  n_occurrences++;
+		}
+	      else
+		/* If we are in a SET_DEST, suppress most cases unless we
+		   have gone inside a MEM, in which case we want to
+		   simplify the address.  We assume here that things that
+		   are actually part of the destination have their inner
+		   parts in the first expression.  This is true for SUBREG, 
+		   STRICT_LOW_PART, and ZERO_EXTRACT, which are the only
+		   things aside from REG and MEM that should appear in a
+		   SET_DEST.  */
+		new = subst (XEXP (x, i), from, to,
+			     (((in_dest
+				&& (code == SUBREG || code == STRICT_LOW_PART
+				    || code == ZERO_EXTRACT))
+			       || code == SET)
+			      && i == 0), unique_copy);
+
+	      /* If we found that we will have to reject this combination,
+		 indicate that by returning the CLOBBER ourselves, rather than
+		 an expression containing it.  This will speed things up as
+		 well as prevent accidents where two CLOBBERs are considered
+		 to be equal, thus producing an incorrect simplification.  */
+
+	      if (GET_CODE (new) == CLOBBER && XEXP (new, 0) == const0_rtx)
+		return new;
+
+	      SUBST (XEXP (x, i), new);
 	    }
-	  else
-	    /* If we are in a SET_DEST, suppress most cases unless we
-	       have gone inside a MEM, in which case we want to
-	       simplify the address.  We assume here that things that
-	       are actually part of the destination have their inner
-	       parts in the first expression.  This is true for SUBREG, 
-	       STRICT_LOW_PART, and ZERO_EXTRACT, which are the only
-	       things aside from REG and MEM that should appear in a
-	       SET_DEST.  */
-	    new = subst (XEXP (x, i), from, to,
-			 (((in_dest
-			    && (code == SUBREG || code == STRICT_LOW_PART
-				|| code == ZERO_EXTRACT))
-			   || code == SET)
-			  && i == 0), unique_copy);
-
-	  /* If we found that we will have to reject this combination,
-	     indicate that by returning the CLOBBER ourselves, rather than
-	     an expression containing it.  This will speed things up as
-	     well as prevent accidents where two CLOBBERs are considered
-	     to be equal, thus producing an incorrect simplification.  */
-
-	  if (GET_CODE (new) == CLOBBER && XEXP (new, 0) == const0_rtx)
-	    return new;
-
-	  SUBST (XEXP (x, i), new);
 	}
     }