[gcc(refs/vendors/ARM/heads/gcs-13)] aarch64: Add __builtin_aarch64_chkfeat

[gcc(refs/vendors/ARM/heads/gcs-13)] aarch64: Add __builtin_aarch64_chkfeat

[Szabolcs Nagy]

https://gcc.gnu.org/g:8e623cab64d6b4b2d18ab8c3983ec4cca723cfe8

commit 8e623cab64d6b4b2d18ab8c3983ec4cca723cfe8
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Tue May 9 15:24:18 2023 +0100

    aarch64: Add __builtin_aarch64_chkfeat
    
    Builtin for chkfeat: the input argument is used to initialize x16 then
    execute chkfeat and return the updated x16.
    
    Note: ACLE __chkfeat(x) plans to flip the bits to be more intuitive
    (xor the input to output), but for the builtin that seems unnecessary
    complication.
    
    gcc/ChangeLog:
    
            * config/aarch64/aarch64-builtins.cc (enum aarch64_builtins):
            Define AARCH64_BUILTIN_CHKFEAT.
            (aarch64_general_init_builtins): Handle chkfeat.
            (aarch64_general_expand_builtin): Handle chkfeat.

Diff:
---
 gcc/config/aarch64/aarch64-builtins.cc | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/gcc/config/aarch64/aarch64-builtins.cc b/gcc/config/aarch64/aarch64-builtins.cc
index dd9f11501657..cff7836e9480 100644
--- a/gcc/config/aarch64/aarch64-builtins.cc
+++ b/gcc/config/aarch64/aarch64-builtins.cc
@@ -785,6 +785,8 @@ enum aarch64_builtins
   AARCH64_RBIT,
   AARCH64_RBITL,
   AARCH64_RBITLL,
+  /* Armv8.9-A / Armv9.4-A builtins.  */
+  AARCH64_BUILTIN_CHKFEAT,
   AARCH64_BUILTIN_MAX
 };
 
@@ -2017,6 +2019,12 @@ aarch64_general_init_builtins (void)
   if (TARGET_MEMTAG)
     aarch64_init_memtag_builtins ();
 
+  tree ftype_chkfeat
+    = build_function_type_list (uint64_type_node, uint64_type_node, NULL);
+  aarch64_builtin_decls[AARCH64_BUILTIN_CHKFEAT]
+    = aarch64_general_add_builtin ("__builtin_aarch64_chkfeat", ftype_chkfeat,
+				   AARCH64_BUILTIN_CHKFEAT);
+
   if (in_lto_p)
     handle_arm_acle_h ();
 }
@@ -2809,6 +2817,16 @@ aarch64_general_expand_builtin (unsigned int fcode, tree exp, rtx target,
     case AARCH64_BUILTIN_RNG_RNDR:
     case AARCH64_BUILTIN_RNG_RNDRRS:
       return aarch64_expand_rng_builtin (exp, target, fcode, ignore);
+
+    case AARCH64_BUILTIN_CHKFEAT:
+      {
+	rtx x16_reg = gen_rtx_REG (DImode, R16_REGNUM);
+	op0 = expand_normal (CALL_EXPR_ARG (exp, 0));
+	emit_move_insn (x16_reg, op0);
+	expand_insn (CODE_FOR_aarch64_chkfeat, 0, 0);
+	emit_move_insn (target, x16_reg);
+	return target;
+      }
     }
 
   if (fcode >= AARCH64_SIMD_BUILTIN_BASE && fcode <= AARCH64_SIMD_BUILTIN_MAX)