I was asked to split V4 patch #4.2 into smaller chuncks. This patch is one of
8 patches that were broken out from 4.2. Another patch from 4.2 to use
SIGNED_16BIT_OFFSET_EXTRA_P has already been committed.
This patch adjusts the insn cost to treat prefixed instructions the same as
non-prefixed instructions, rather than making them seem 3 times as expensive,
since the prefixed instruction length is 12 bytes compared to the normal 4
bytes.
Using all of the patches in this series, I have bootstrapped the compiler on a
little endian power8 system and ran the regression tests. In addition, I have
built the Spec 2006 and 2017 benchmark suites, for -mcpu=power8, -mcpu=power9,
and -mcpu=future, and all of the benchmarks build. Can I check this into the
trunk?
2019-10-03 Michael Meissner <meiss...@linux.ibm.com>
* config/rs6000/rs6000.c (rs6000_insn_cost): Do not make prefixed
instructions cost more because they are larger in size.
Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c (revision 276535)
+++ gcc/config/rs6000/rs6000.c (working copy)
@@ -20972,14 +20972,38 @@ rs6000_insn_cost (rtx_insn *insn, bool s
if (recog_memoized (insn) < 0)
return 0;
- if (!speed)
- return get_attr_length (insn);
+ if (speed)
+ {
+ int cost = get_attr_cost (insn);
+ if (cost > 0)
+ return cost;
+ }
- int cost = get_attr_cost (insn);
- if (cost > 0)
- return cost;
+ int cost;
+ int length = get_attr_length (insn);
+ int n = length / 4;
+
+ /* How many real instructions are generated for this insn? This is slightly
+ different from the length attribute, in that the length attribute counts
+ the number of bytes. With prefixed instructions, we don't want to count a
+ prefixed instruction (length 12 bytes including possible NOP) as taking 3
+ instructions, but just one. */
+ if (length >= 12 && get_attr_prefixed (insn) == PREFIXED_YES)
+ {
+ /* Single prefixed instruction. */
+ if (length == 12)
+ n = 1;
+
+ /* A normal instruction and a prefixed instruction (16) or two back
+ to back prefixed instructions (20). */
+ else if (length == 16 || length == 20)
+ n = 2;
+
+ /* Guess for larger instruction sizes. */
+ else
+ n = 2 + (length - 20) / 4;
+ }
- int n = get_attr_length (insn) / 4;
enum attr_type type = get_attr_type (insn);
switch (type)
--
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
