[PATCH 2/16][ARM] PR/63870 Add __builtin_arm_lane_check.

[Alan Lawrence]

As per https://gcc.gnu.org/ml/gcc-patches/2015-04/msg01334.html

commit 1bb1b208a2c8c8b1ee1186c6128a498583fd64fe
Author: Alan Lawrence <alan.lawre...@arm.com>
Date:   Mon Dec 8 18:36:30 2014 +0000

    Add __builtin_arm_lane_check

diff --git a/gcc/config/arm/arm-builtins.c b/gcc/config/arm/arm-builtins.c
index 7f5bf87..89b1b0c 100644
--- a/gcc/config/arm/arm-builtins.c
+++ b/gcc/config/arm/arm-builtins.c
@@ -534,12 +534,16 @@ enum arm_builtins
 #undef CRYPTO2
 #undef CRYPTO3
 
+  ARM_BUILTIN_NEON_BASE,
+  ARM_BUILTIN_NEON_LANE_CHECK = ARM_BUILTIN_NEON_BASE,
+
 #include "arm_neon_builtins.def"
 
   ARM_BUILTIN_MAX
 };
 
-#define ARM_BUILTIN_NEON_BASE (ARM_BUILTIN_MAX - ARRAY_SIZE (neon_builtin_data))
+#define ARM_BUILTIN_NEON_PATTERN_START \
+    (ARM_BUILTIN_MAX - ARRAY_SIZE (neon_builtin_data))
 
 #undef CF
 #undef VAR1
@@ -898,7 +902,7 @@ arm_init_simd_builtin_scalar_types (void)
 static void
 arm_init_neon_builtins (void)
 {
-  unsigned int i, fcode = ARM_BUILTIN_NEON_BASE;
+  unsigned int i, fcode = ARM_BUILTIN_NEON_PATTERN_START;
 
   arm_init_simd_builtin_types ();
 
@@ -908,6 +912,15 @@ arm_init_neon_builtins (void)
      system.  */
   arm_init_simd_builtin_scalar_types ();
 
+  tree lane_check_fpr = build_function_type_list (void_type_node,
+						  intSI_type_node,
+						  intSI_type_node,
+						  NULL);
+  arm_builtin_decls[ARM_BUILTIN_NEON_LANE_CHECK] =
+      add_builtin_function ("__builtin_arm_lane_check", lane_check_fpr,
+			    ARM_BUILTIN_NEON_LANE_CHECK, BUILT_IN_MD,
+			    NULL, NULL_TREE);
+
   for (i = 0; i < ARRAY_SIZE (neon_builtin_data); i++, fcode++)
     {
       bool print_type_signature_p = false;
@@ -2171,14 +2184,28 @@ arm_expand_neon_args (rtx target, machine_mode map_mode, int fcode,
   return target;
 }
 
-/* Expand a Neon builtin. These are "special" because they don't have symbolic
+/* Expand a Neon builtin, i.e. those registered only if TARGET_NEON holds.
+   Most of these are "special" because they don't have symbolic
    constants defined per-instruction or per instruction-variant. Instead, the
    required info is looked up in the table neon_builtin_data.  */
 static rtx
 arm_expand_neon_builtin (int fcode, tree exp, rtx target)
 {
+  if (fcode == ARM_BUILTIN_NEON_LANE_CHECK)
+    {
+      tree nlanes = CALL_EXPR_ARG (exp, 0);
+      gcc_assert (TREE_CODE (nlanes) == INTEGER_CST);
+      rtx lane_idx = expand_normal (CALL_EXPR_ARG (exp, 1));
+      if (CONST_INT_P (lane_idx))
+	neon_lane_bounds (lane_idx, 0, TREE_INT_CST_LOW (nlanes), exp);
+      else
+	error ("%Klane index must be a constant immediate", exp);
+      /* Don't generate any RTL.  */
+      return const0_rtx;
+    }
+
   neon_builtin_datum *d =
-		&neon_builtin_data[fcode - ARM_BUILTIN_NEON_BASE];
+		&neon_builtin_data[fcode - ARM_BUILTIN_NEON_PATTERN_START];
   enum insn_code icode = d->code;
   builtin_arg args[SIMD_MAX_BUILTIN_ARGS];
   int num_args = insn_data[d->code].n_operands;