reload1.c (alter_reg): Require the alignment of the stack slot to be at least…

reload1.c (alter_reg): Require the alignment of the stack slot to be at least reg_max_ref_width bytes.

gcc/
	* reload1.c (alter_reg): Require the alignment of the stack slot to
	be at least reg_max_ref_width bytes.
	(scan_paradoxical_subregs): Record the largest width in
	reg_max_ref_width.

From-SVN: r117252

gcc/ChangeLog

+2006-09-27  Richard Sandiford  <richard@codesourcery.com>
+
+	* reload1.c (alter_reg): Require the alignment of the stack slot to
+	be at least reg_max_ref_width bytes.
+	(scan_paradoxical_subregs): Record the largest width in
+	reg_max_ref_width.
+
 2006-09-26  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/25261

gcc/reload1.c

@@ -1996,8 +1996,11 @@ alter_reg (int i, int from_reg)
       && reg_equiv_memory_loc[i] == 0)
     {
       rtx x;
+      enum machine_mode mode = GET_MODE (regno_reg_rtx[i]);
       unsigned int inherent_size = PSEUDO_REGNO_BYTES (i);
+      unsigned int inherent_align = GET_MODE_ALIGNMENT (mode);
       unsigned int total_size = MAX (inherent_size, reg_max_ref_width[i]);
+      unsigned int min_align = reg_max_ref_width[i] * BITS_PER_UNIT;
       int adjust = 0;
 
       /* Each pseudo reg has an inherent size which comes from its own mode,
@@ -2011,8 +2014,9 @@ alter_reg (int i, int from_reg)
       if (from_reg == -1)
 	{
 	  /* No known place to spill from => no slot to reuse.  */
-	  x = assign_stack_local (GET_MODE (regno_reg_rtx[i]), total_size,
-				  inherent_size == total_size ? 0 : -1);
+	  x = assign_stack_local (mode, total_size,
+				  min_align > inherent_align
+				  || total_size > inherent_size ? -1 : 0);
 	  if (BYTES_BIG_ENDIAN)
 	    /* Cancel the  big-endian correction done in assign_stack_local.
 	       Get the address of the beginning of the slot.
@@ -2028,7 +2032,8 @@ alter_reg (int i, int from_reg)
       else if (spill_stack_slot[from_reg] != 0
 	       && spill_stack_slot_width[from_reg] >= total_size
 	       && (GET_MODE_SIZE (GET_MODE (spill_stack_slot[from_reg]))
-		   >= inherent_size))
+		   >= inherent_size)
+	       && MEM_ALIGN (spill_stack_slot[from_reg]) >= min_align)
 	x = spill_stack_slot[from_reg];
 
       /* Allocate a bigger slot.  */
@@ -2036,7 +2041,6 @@ alter_reg (int i, int from_reg)
 	{
 	  /* Compute maximum size needed, both for inherent size
 	     and for total size.  */
-	  enum machine_mode mode = GET_MODE (regno_reg_rtx[i]);
 	  rtx stack_slot;
 
 	  if (spill_stack_slot[from_reg])
@@ -2046,11 +2050,14 @@ alter_reg (int i, int from_reg)
 		mode = GET_MODE (spill_stack_slot[from_reg]);
 	      if (spill_stack_slot_width[from_reg] > total_size)
 		total_size = spill_stack_slot_width[from_reg];
+	      if (MEM_ALIGN (spill_stack_slot[from_reg]) > min_align)
+		min_align = MEM_ALIGN (spill_stack_slot[from_reg]);
 	    }
 
 	  /* Make a slot with that size.  */
 	  x = assign_stack_local (mode, total_size,
-				  inherent_size == total_size ? 0 : -1);
+				  min_align > inherent_align
+				  || total_size > inherent_size ? -1 : 0);
 	  stack_slot = x;
 
 	  /* All pseudos mapped to this slot can alias each other.  */
@@ -3828,7 +3835,8 @@ scan_paradoxical_subregs (rtx x)
 
     case SUBREG:
       if (REG_P (SUBREG_REG (x))
-	  && GET_MODE_SIZE (GET_MODE (x)) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))
+	  && (GET_MODE_SIZE (GET_MODE (x))
+	      > reg_max_ref_width[REGNO (SUBREG_REG (x))]))
 	reg_max_ref_width[REGNO (SUBREG_REG (x))]
 	  = GET_MODE_SIZE (GET_MODE (x));
       return;