[026/nnn] poly_int: operand_subword

[Richard Sandiford <richard.sandiford@linaro.org>]

This patch makes operand_subword and operand_subword_force take
polynomial offsets.  This is a fairly old-school interface and
these days should only be used when splitting multiword operations
into word operations.  It still doesn't hurt to support polynomial
offsets and it helps make callers easier to write.


2017-10-23  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* rtl.h (operand_subword, operand_subword_force): Take the offset
	as a poly_uint64 an unsigned int.
	* emit-rtl.c (operand_subword, operand_subword_force): Likewise.

Index: gcc/rtl.h
===================================================================
--- gcc/rtl.h	2017-10-23 17:16:50.374527737 +0100
+++ gcc/rtl.h	2017-10-23 17:16:55.754801166 +0100
@@ -3017,10 +3017,10 @@ extern rtx gen_lowpart_if_possible (mach
 /* In emit-rtl.c */
 extern rtx gen_highpart (machine_mode, rtx);
 extern rtx gen_highpart_mode (machine_mode, machine_mode, rtx);
-extern rtx operand_subword (rtx, unsigned int, int, machine_mode);
+extern rtx operand_subword (rtx, poly_uint64, int, machine_mode);
 
 /* In emit-rtl.c */
-extern rtx operand_subword_force (rtx, unsigned int, machine_mode);
+extern rtx operand_subword_force (rtx, poly_uint64, machine_mode);
 extern int subreg_lowpart_p (const_rtx);
 extern poly_uint64 subreg_size_lowpart_offset (poly_uint64, poly_uint64);
 
Index: gcc/emit-rtl.c
===================================================================
--- gcc/emit-rtl.c	2017-10-23 17:16:50.363529222 +0100
+++ gcc/emit-rtl.c	2017-10-23 17:16:55.754801166 +0100
@@ -1736,7 +1736,8 @@ subreg_lowpart_p (const_rtx x)
  */
 
 rtx
-operand_subword (rtx op, unsigned int offset, int validate_address, machine_mode mode)
+operand_subword (rtx op, poly_uint64 offset, int validate_address,
+		 machine_mode mode)
 {
   if (mode == VOIDmode)
     mode = GET_MODE (op);
@@ -1745,12 +1746,12 @@ operand_subword (rtx op, unsigned int of
 
   /* If OP is narrower than a word, fail.  */
   if (mode != BLKmode
-      && (GET_MODE_SIZE (mode) < UNITS_PER_WORD))
+      && may_lt (GET_MODE_SIZE (mode), UNITS_PER_WORD))
     return 0;
 
   /* If we want a word outside OP, return zero.  */
   if (mode != BLKmode
-      && (offset + 1) * UNITS_PER_WORD > GET_MODE_SIZE (mode))
+      && may_gt ((offset + 1) * UNITS_PER_WORD, GET_MODE_SIZE (mode)))
     return const0_rtx;
 
   /* Form a new MEM at the requested address.  */
@@ -1784,7 +1785,7 @@ operand_subword (rtx op, unsigned int of
    MODE is the mode of OP, in case it is CONST_INT.  */
 
 rtx
-operand_subword_force (rtx op, unsigned int offset, machine_mode mode)
+operand_subword_force (rtx op, poly_uint64 offset, machine_mode mode)
 {
   rtx result = operand_subword (op, offset, 1, mode);