[gcc r14-4001] gcc: xtensa: use salt/saltu in xtensa_expand_scc

[gcc r14-4001] gcc: xtensa: use salt/saltu in xtensa_expand_scc

[Max Filippov]

https://gcc.gnu.org/g:fd948fd846c7de29150872e43b63bf9128da5b8f

commit r14-4001-gfd948fd846c7de29150872e43b63bf9128da5b8f
Author: Max Filippov <jcmvbkbc@gmail.com>
Date:   Wed Sep 6 20:13:22 2023 -0700

    gcc: xtensa: use salt/saltu in xtensa_expand_scc
    
    gcc/
            * config/xtensa/predicates.md (xtensa_cstoresi_operator): Add
            unsigned comparisons.
            * config/xtensa/xtensa.cc (xtensa_expand_scc): Add code
            generation of salt/saltu instructions.
            * config/xtensa/xtensa.h (TARGET_SALT): New macro.
            * config/xtensa/xtensa.md (salt, saltu): New instruction
            patterns.

Diff:
---
 gcc/config/xtensa/predicates.md |  2 +-
 gcc/config/xtensa/xtensa.cc     | 55 +++++++++++++++++++++++++++++++++++++++++
 gcc/config/xtensa/xtensa.h      |  1 +
 gcc/config/xtensa/xtensa.md     | 20 +++++++++++++++
 4 files changed, 77 insertions(+), 1 deletion(-)

diff --git a/gcc/config/xtensa/predicates.md b/gcc/config/xtensa/predicates.md
index a3575a68892..672fb003a6c 100644
--- a/gcc/config/xtensa/predicates.md
+++ b/gcc/config/xtensa/predicates.md
@@ -195,7 +195,7 @@
   (match_code "plus,minus"))
 
 (define_predicate "xtensa_cstoresi_operator"
-  (match_code "eq,ne,gt,ge,lt,le"))
+  (match_code "eq,ne,gt,ge,lt,le,gtu,geu,ltu,leu"))
 
 (define_predicate "xtensa_shift_per_byte_operator"
   (match_code "ashift,ashiftrt,lshiftrt"))
diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc
index 2481b028ca1..a4f8e3e49d0 100644
--- a/gcc/config/xtensa/xtensa.cc
+++ b/gcc/config/xtensa/xtensa.cc
@@ -995,6 +995,61 @@ xtensa_expand_scc (rtx operands[4], machine_mode cmp_mode)
   rtx one_tmp, zero_tmp;
   rtx (*gen_fn) (rtx, rtx, rtx, rtx, rtx);
 
+  if (cmp_mode == SImode && TARGET_SALT)
+    {
+      rtx a = operands[2], b = force_reg (SImode, operands[3]);
+      enum rtx_code code = GET_CODE (operands[1]);
+      bool invert_res = false;
+
+      switch (code)
+	{
+	case GE:
+	case GEU:
+	  invert_res = true;
+	  break;
+	case GT:
+	case GTU:
+	  std::swap (a, b);
+	  break;
+	case LE:
+	case LEU:
+	  invert_res = true;
+	  std::swap (a, b);
+	  break;
+	default:
+	  break;
+	}
+
+      switch (code)
+	{
+	case GE:
+	case GT:
+	case LE:
+	case LT:
+	  emit_insn (gen_salt (dest, a, b));
+	  if (!invert_res)
+	    return 1;
+	  break;
+	case GEU:
+	case GTU:
+	case LEU:
+	case LTU:
+	  emit_insn (gen_saltu (dest, a, b));
+	  if (!invert_res)
+	    return 1;
+	  break;
+	default:
+	  break;
+	}
+
+      if (invert_res)
+	{
+	  emit_insn (gen_negsi2 (dest, dest));
+	  emit_insn (gen_addsi3 (dest, dest, const1_rtx));
+	  return 1;
+	}
+    }
+
   if (! (cmp = gen_conditional_move (GET_CODE (operands[1]), cmp_mode,
 				     operands[2], operands[3])))
     return 0;
diff --git a/gcc/config/xtensa/xtensa.h b/gcc/config/xtensa/xtensa.h
index 34e06afcff4..5987681e549 100644
--- a/gcc/config/xtensa/xtensa.h
+++ b/gcc/config/xtensa/xtensa.h
@@ -54,6 +54,7 @@ along with GCC; see the file COPYING3.  If not see
 #define TARGET_WINDOWED_ABI	xtensa_windowed_abi
 #define TARGET_DEBUG		XCHAL_HAVE_DEBUG
 #define TARGET_L32R		XCHAL_HAVE_L32R
+#define TARGET_SALT		(XTENSA_MARCH_EARLIEST >= 260000)
 
 #define TARGET_DEFAULT (MASK_SERIALIZE_VOLATILE)
 
diff --git a/gcc/config/xtensa/xtensa.md b/gcc/config/xtensa/xtensa.md
index 6476fdc395a..20af1cbfbd0 100644
--- a/gcc/config/xtensa/xtensa.md
+++ b/gcc/config/xtensa/xtensa.md
@@ -2393,6 +2393,26 @@
   DONE;
 })
 
+(define_insn "salt"
+  [(set (match_operand:SI 0 "register_operand" "=a")
+	(lt:SI (match_operand:SI 1 "register_operand" "r")
+	       (match_operand:SI 2 "register_operand" "r")))]
+  "TARGET_SALT"
+  "salt\t%0, %1, %2"
+  [(set_attr "type"	"arith")
+   (set_attr "mode"	"SI")
+   (set_attr "length"	"3")])
+
+(define_insn "saltu"
+  [(set (match_operand:SI 0 "register_operand" "=a")
+	(ltu:SI (match_operand:SI 1 "register_operand" "r")
+		(match_operand:SI 2 "register_operand" "r")))]
+  "TARGET_SALT"
+  "saltu\t%0, %1, %2"
+  [(set_attr "type"	"arith")
+   (set_attr "mode"	"SI")
+   (set_attr "length"	"3")])
+
 (define_expand "cstoresf4"
   [(match_operand:SI 0 "register_operand")
    (match_operator:SI 1 "comparison_operator"