[gcc(refs/users/meissner/heads/dmf001)] Add accumulator_operand.

[Michael Meissner <meissner@gcc.gnu.org>]

https://gcc.gnu.org/g:9af78e29a3a16ec1ab33cf31c2c5c33ce7e325a7

commit 9af78e29a3a16ec1ab33cf31c2c5c33ce7e325a7
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Tue Oct 11 18:40:43 2022 -0400

    Add accumulator_operand.
    
    2022-10-11   Michael Meissner  <meissner@linux.ibm.com>
    
    gcc/
    
            * config/rs6000/predicates.md (accumulator_operand): New predicate.

Diff:
---
 gcc/config/rs6000/predicates.md | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/gcc/config/rs6000/predicates.md b/gcc/config/rs6000/predicates.md
index 51aa0f7449e..5fcda8543b2 100644
--- a/gcc/config/rs6000/predicates.md
+++ b/gcc/config/rs6000/predicates.md
@@ -199,6 +199,24 @@
   return DMF_REGNO_P (REGNO (op));
 })
 
+;; Return 1 if op is an accumulator.  On power10 systems, the accumulators
+;; overlap with the FPRs, while on systems with DMF, the accumulators are
+;; separate dense math registers and do not overlap with the FPR registers..
+(define_predicate "accumulator_operand"
+  (match_operand 0 "register_operand")
+{
+  if (!REG_P (op))
+    return 0;
+
+  if (!HARD_REGISTER_P (op))
+    return 1;
+
+  int r = REGNO (op);
+  return (TARGET_DMF
+	  ? DMF_REGNO_P (r)
+	  : FP_REGNO_P (r) && (r & 3) == 0);
+})
+
 ;; Return 1 if op is the carry register.
 (define_predicate "ca_operand"
   (match_operand 0 "register_operand")