This patch incorporates large offsets for -mcpu=future when we optimization a
vector extract from memory and the memory address previously had been a
prefixed address with a large offset.
The current code would generate loading up the constant into a temporary and
then doing an indexed load. Successive passes would eventually optimize that
back into the form we want (having the base register plus a large offset), but
it is better to generate the optimial code sooner.
I have bootstrapped this change on a little endian power8 system and there were
no regressions. Can I check this into the trunk?
2019-12-20 Michael Meissner <meiss...@linux.ibm.com>
* config/rs6000/rs6000.c (rs6000_adjust_vec_address): Add support
for the offset being 34-bits when -mcpu=future is used.
Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c (revision 279553)
+++ gcc/config/rs6000/rs6000.c (working copy)
@@ -6792,9 +6792,17 @@ rs6000_adjust_vec_address (rtx scalar_re
HOST_WIDE_INT offset = INTVAL (op1) + INTVAL (element_offset);
rtx offset_rtx = GEN_INT (offset);
- if (IN_RANGE (offset, -32768, 32767)
+ /* 16-bit offset. */
+ if (SIGNED_INTEGER_16BIT_P (offset)
&& (scalar_size < 8 || (offset & 0x3) == 0))
new_addr = gen_rtx_PLUS (Pmode, op0, offset_rtx);
+
+ /* 34-bit offset if we have prefixed addresses. */
+ else if (TARGET_PREFIXED_ADDR && SIGNED_INTEGER_34BIT_P (offset))
+ new_addr = gen_rtx_PLUS (Pmode, op0, offset_rtx);
+
+ /* Offset overflowed, move offset to the temporary (which will likely
+ be split), and do X-FORM addressing. */
else
{
emit_move_insn (base_tmp, offset_rtx);
@@ -6825,6 +6833,12 @@ rs6000_adjust_vec_address (rtx scalar_re
emit_insn (insn);
}
+ /* Make sure we don't overwrite the temporary if the element being
+ extracted is variable, and we've put the offset into base_tmp
+ previously. */
+ else if (rtx_equal_p (base_tmp, element_offset))
+ emit_insn (gen_add2_insn (base_tmp, op1));
+
else
{
/* Make sure base_tmp is not the same as element_offset. This
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meiss...@linux.ibm.com, phone: +1 (978) 899-4797
