Add support for __jcvt intrinsic

This patch implements the __jcvt ACLE intrinsic [1] that maps down to the FJCVTZS [2] instruction from Armv8.3-a.
No fancy mode iterators or nothing. Just a single builtin, UNSPEC and define_insn and the associate plumbing.
This patch also defines __ARM_FEATURE_JCVT to indicate when the intrinsic is available.

[1] https://developer.arm.com/docs/101028/latest/data-processing-intrinsics
[2] https://developer.arm.com/docs/ddi0596/latest/simd-and-floating-point-instructions-alphabetic-order/fjcvtzs-floating-point-javascript-convert-to-signed-fixed-point-rounding-toward-zero

gcc/
	PR target/71233
	* config/aarch64/aarch64.md (UNSPEC_FJCVTZS): Define.
	(aarch64_fjcvtzs): New define_insn.
	* config/aarch64/aarch64.h (TARGET_JSCVT): Define.
	* config/aarch64/aarch64-builtins.c (aarch64_builtins):
	Add AARCH64_JSCVT.
	(aarch64_init_builtins): Initialize __builtin_aarch64_jcvtzs.
	(aarch64_expand_builtin): Handle AARCH64_JSCVT.
	* config/aarch64/aarch64-c.c (aarch64_update_cpp_builtins): Define
	__ARM_FEATURE_JCVT where appropriate.
	* config/aarch64/arm_acle.h (__jcvt): Define.
	* doc/sourcebuild.texi (aarch64_fjcvtzs_hw) Document new
	target supports option.

gcc/testsuite/
	PR target/71233
	* gcc.target/aarch64/acle/jcvt_1.c: New test.
	* gcc.target/aarch64/acle/jcvt_2.c: New testcase.
	* lib/target-supports.exp
	(check_effective_target_aarch64_fjcvtzs_hw): Add new check for
	FJCVTZS hw.

Co-Authored-By: Andrea Corallo  <andrea.corallo@arm.com>

(cherry picked from commit e1d5d19)
(cherry picked from commit 2c62952)
(cherry picked from commit d2b86e1)

gcc/config/aarch64/aarch64-builtins.c

@@ -436,6 +436,8 @@ enum aarch64_builtins
   /* Special cased Armv8.3-A Complex FMA by Lane quad Builtins.  */
   AARCH64_SIMD_FCMLA_LANEQ_BUILTIN_BASE,
   AARCH64_SIMD_FCMLA_LANEQ_BUILTINS
+  /* Builtin for Arm8.3-a Javascript conversion instruction.  */
+  AARCH64_JSCVT,
   AARCH64_BUILTIN_MAX
 };
 
@@ -1086,6 +1088,12 @@ aarch64_init_builtins (void)
   aarch64_init_crc32_builtins ();
   aarch64_init_builtin_rsqrt ();
 
+  tree ftype_jcvt
+    = build_function_type_list (intSI_type_node, double_type_node, NULL);
+  aarch64_builtin_decls[AARCH64_JSCVT]
+    = add_builtin_function ("__builtin_aarch64_jcvtzs", ftype_jcvt,
+			    AARCH64_JSCVT, BUILT_IN_MD, NULL, NULL_TREE);
+
   /* Initialize pointer authentication builtins which are backed by instructions
      in NOP encoding space.
 
@@ -1576,6 +1584,16 @@ aarch64_expand_builtin (tree exp,
 
       return target;
 
+    case AARCH64_JSCVT:
+      {
+	expand_operand ops[2];
+	create_output_operand (&ops[0], target, SImode);
+	op0 = expand_normal (CALL_EXPR_ARG (exp, 0));
+	create_input_operand (&ops[1], op0, DFmode);
+	expand_insn (CODE_FOR_aarch64_fjcvtzs, 2, ops);
+	return ops[0].value;
+      }
+
     case AARCH64_SIMD_BUILTIN_FCMLA_LANEQ0_V2SF:
     case AARCH64_SIMD_BUILTIN_FCMLA_LANEQ90_V2SF:
     case AARCH64_SIMD_BUILTIN_FCMLA_LANEQ180_V2SF:

gcc/config/aarch64/aarch64-c.c

@@ -110,6 +110,7 @@ aarch64_update_cpp_builtins (cpp_reader *pfile)
   aarch64_def_or_undef (TARGET_CRC32, "__ARM_FEATURE_CRC32", pfile);
   aarch64_def_or_undef (TARGET_DOTPROD, "__ARM_FEATURE_DOTPROD", pfile);
   aarch64_def_or_undef (TARGET_COMPLEX, "__ARM_FEATURE_COMPLEX", pfile);
+  aarch64_def_or_undef (TARGET_JSCVT, "__ARM_FEATURE_JCVT", pfile);
 
   cpp_undef (pfile, "__AARCH64_CMODEL_TINY__");
   cpp_undef (pfile, "__AARCH64_CMODEL_SMALL__");

gcc/config/aarch64/aarch64.h

@@ -274,6 +274,9 @@ extern unsigned aarch64_architecture_version;
 /* ARMv8.3-A features.  */
 #define TARGET_ARMV8_3	(AARCH64_ISA_V8_3)
 
+/* Javascript conversion instruction from Armv8.3-a.  */
+#define TARGET_JSCVT	(TARGET_FLOAT && AARCH64_ISA_V8_3)
+
 /* Armv8.3-a Complex number extension to AdvSIMD extensions.  */
 #define TARGET_COMPLEX (TARGET_SIMD && TARGET_ARMV8_3)
 

gcc/config/aarch64/aarch64.md

@@ -138,6 +138,7 @@
     UNSPEC_CRC32X
     UNSPEC_FCVTZS
     UNSPEC_FCVTZU
+    UNSPEC_FJCVTZS
     UNSPEC_URECPE
     UNSPEC_FRECPE
     UNSPEC_FRECPS
@@ -6836,6 +6837,16 @@
   [(set_attr "length" "0")]
 )
 
+(define_insn "aarch64_fjcvtzs"
+  [(set (match_operand:SI 0 "register_operand" "=r")
+	(unspec:SI [(match_operand:DF 1 "register_operand" "w")]
+		   UNSPEC_FJCVTZS))
+   (clobber (reg:CC CC_REGNUM))]
+  "TARGET_JSCVT"
+  "fjcvtzs\\t%w0, %d1"
+  [(set_attr "type" "f_cvtf2i")]
+)
+
 ;; Pointer authentication patterns are always provided.  In architecture
 ;; revisions prior to ARMv8.3-A these HINT instructions operate as NOPs.
 ;; This lets the user write portable software which authenticates pointers

gcc/config/aarch64/arm_acle.h

@@ -29,6 +29,20 @@
 
 #include <stdint.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#pragma GCC push_options
+#pragma GCC target ("arch=armv8.3-a")
+__extension__ static __inline int32_t __attribute__ ((__always_inline__))
+__jcvt (double __a)
+{
+  return __builtin_aarch64_jcvtzs (__a);
+}
+
+#pragma GCC pop_options
+
 #pragma GCC push_options
 
 #pragma GCC target ("+nothing+crc")

gcc/doc/sourcebuild.texi

@@ -1927,6 +1927,9 @@ AArch64 target which generates instruction sequences for big endian.
 Binutils installed on test system supports relocation types required by -fpic
 for AArch64 small memory model.
 
+@item aarch64_fjcvtzs_hw
+AArch64 target that is able to generate and execute armv8.3-a FJCVTZS
+instruction.
 @end table
 
 @subsubsection MIPS-specific attributes

gcc/testsuite/gcc.target/aarch64/acle/jcvt_1.c

@@ -0,0 +1,15 @@
+/* Test the __jcvt ACLE intrinsic.  */
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=armv8.3-a" } */
+
+#include <arm_acle.h>
+
+#ifdef __ARM_FEATURE_JCVT
+int32_t
+test_jcvt (double a)
+{
+  return __jcvt (a);
+}
+#endif
+
+/* { dg-final { scan-assembler-times "fjcvtzs\tw\[0-9\]+, d\[0-9\]+\n" 1 } } */

gcc/testsuite/gcc.target/aarch64/acle/jcvt_2.c

@@ -0,0 +1,33 @@
+/* Test the __jcvt ACLE intrinsic.  */
+/* { dg-do run } */
+/* { dg-options "-O2 -march=armv8.3-a -save-temps" } */
+/* { dg-require-effective-target aarch64_fjcvtzs_hw } */
+
+#include <arm_acle.h>
+
+extern void abort (void);
+
+#ifdef __ARM_FEATURE_JCVT
+volatile int32_t x;
+
+int __attribute__((noinline))
+foo (double a, int b, int c)
+{
+  b = b > c;
+  x = __jcvt (a);
+  return b;
+}
+
+int
+main (void)
+{
+  int x = foo (1.1, 2, 3);
+  if (x)
+    abort ();
+
+  return 0;
+}
+
+#endif
+
+/* { dg-final { scan-assembler-times "fjcvtzs\tw\[0-9\]+, d\[0-9\]+\n" 1 } } */

gcc/testsuite/lib/target-supports.exp

@@ -4414,6 +4414,27 @@ proc check_effective_target_aarch64_bti_hw { } {
     } "-O2" ]
 }
 
+# Return 1 if the target supports executing the armv8.3-a FJCVTZS
+# instruction.
+proc check_effective_target_aarch64_fjcvtzs_hw { } {
+    if { ![istarget aarch64*-*-*] } {
+	return 0
+    }
+    return [check_runtime aarch64_fjcvtzs_hw_available {
+	int
+	main (void)
+	{
+	  double in = 25.1;
+	  int out;
+	  asm volatile ("fjcvtzs %w0, %d1"
+			: "=r" (out)
+			: "w" (in)
+			: /* No clobbers.  */);
+	  return out != 25;
+	}
+    } "-march=armv8.3-a" ]
+}
+
 # Return 1 if GCC was configured with --enable-standard-branch-protection
 proc check_effective_target_default_branch_protection { } {
     return [check_configured_with "enable-standard-branch-protection"]