[gcc r14-4148] Fix bogus operand predicate on iq2000

[gcc r14-4148] Fix bogus operand predicate on iq2000

[Jeff Law]

https://gcc.gnu.org/g:eec7c373c2de6d5806537552de5f5b2bd064c43e

commit r14-4148-geec7c373c2de6d5806537552de5f5b2bd064c43e
Author: Jeff Law <jlaw@ventanamicro.com>
Date:   Tue Sep 19 11:28:53 2023 -0600

    Fix bogus operand predicate on iq2000
    
    The iq2000-elf port regressed these tests recently:
    
    > iq2000-sim: gcc.c-torture/execute/20040703-1.c   -O2  (test for excess errors)
    > iq2000-sim: gcc.c-torture/execute/20040703-1.c   -O2 -flto -fno-use-linker-plugin -flto-partition=none  (test for excess errors)
    > iq2000-sim: gcc.c-torture/execute/20040703-1.c   -O3 -g  (test for excess errors)
    
    It turns out one of the patterns had an operand predicate that allowed REG,
    SUBREG, CONST_INT (with a limited set of CONST_INTs).  Yet the constraint only
    allowed the limited set of immediates.  This naturally triggered an LRA
    constraint failure.
    
    The fix is trivial, create an operand predicate that accurately reflects the
    kinds of operands allowed by the instruction.
    
    It turns out this was a long standing bug -- fixing the pattern resolved 55
    failing tests in the testsuite.
    
    gcc/
            * config/iq2000/predicates.md (uns_arith_constant): New predicate.
            * config/iq2000/iq2000.md (rotrsi3): Use it.

Diff:
---
 gcc/config/iq2000/iq2000.md     | 2 +-
 gcc/config/iq2000/predicates.md | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/gcc/config/iq2000/iq2000.md b/gcc/config/iq2000/iq2000.md
index aaeda39ae99..f157a82ebc0 100644
--- a/gcc/config/iq2000/iq2000.md
+++ b/gcc/config/iq2000/iq2000.md
@@ -988,7 +988,7 @@
 (define_insn "rotrsi3"
   [(set (match_operand:SI 0 "register_operand" "=r")
         (rotatert:SI (match_operand:SI 1 "register_operand" "r")
-                     (match_operand:SI 2 "uns_arith_operand" "O")))]
+                     (match_operand:SI 2 "uns_arith_constant" "O")))]
   ""
   "ram %0,%1,%2,0x0,0x0"
   [(set_attr "type" "arith")])
diff --git a/gcc/config/iq2000/predicates.md b/gcc/config/iq2000/predicates.md
index 1330f7d613c..38857e17c24 100644
--- a/gcc/config/iq2000/predicates.md
+++ b/gcc/config/iq2000/predicates.md
@@ -17,6 +17,15 @@
 ;; along with GCC; see the file COPYING3.  If not see
 ;; <http://www.gnu.org/licenses/>.
 
+;; Return 1 if OP can be used as an operand where a 16-bit
+;; unsigned integer is needed.
+
+(define_predicate "uns_arith_constant"
+  (match_code "const_int")
+{
+  return SMALL_INT_UNSIGNED (op);
+})
+
 ;; Return 1 if OP can be used as an operand where a register or 16-bit
 ;; unsigned integer is needed.