arm: testsuite: improve guard checks for arm_neon.h

The header file arm_neon.h provides the Advanced SIMD intrinsics that
are available on armv7 or later A & R profile cores.  However, they
are not compatible with M-profile and we also need to ensure that the
FP instructions are enabled (with -mfloat-abi=softfp/hard).  That
leads to some complicated checking as arm_neon.h includes stdint.h
and, at least on linux, that can require that the appropriate ABI
bits/ headers are also installed.

This patch adds a new check to target-supports.exp to establish the
minimal set of option overrides needed to enable use of this header in
a test.

gcc/testsuite:
	* lib/target-supports.exp
	(check_effective_target_arm_neon_h_ok_nocache): New function.
	(check_effective_target_arm_neon_h_ok): Likewise.
	(add_options_for_arm_neon_h): Likewise.
	(check_effective_target_arm_libc_fp_abi_ok_nocache): Allow any
	Arm target, not just arm32.
	* gcc.target/arm/attr-neon-builtin-fail.c: Use it.
	* gcc.target/arm/attr-neon-builtin-fail2.c: Likewise.
	* gcc.target/arm/attr-neon-fp16.c: Likewise.
	* gcc.target/arm/attr-neon2.c: Likewise.

gcc/testsuite/gcc.target/arm/attr-neon-builtin-fail.c

@@ -1,9 +1,8 @@
 /* Check that calling a neon builtin from a function compiled with vfp fails.  */
 /* { dg-do compile } */
-/* { dg-require-effective-target arm_fp_ok } */
-/* { dg-require-effective-target arm_neon_ok } */
+/* { dg-require-effective-target arm_neon_h_ok } */
 /* { dg-options "-O2" } */
-/* { dg-add-options arm_fp } */
+/* { dg-add-options arm_neon_h } */
 
 #include <arm_neon.h>
 
@@ -15,4 +14,3 @@ foo (uint8x16_t *p)
 }
 
 /* { dg-error "inlining failed in call to 'always_inline'" "" { target *-*-* } 0 } */
-

gcc/testsuite/gcc.target/arm/attr-neon-builtin-fail2.c

@@ -1,8 +1,8 @@
 /* Check that calling a neon builtin from a function compiled with vfp fails.  */
 /* { dg-do compile } */
-/* { dg-require-effective-target arm_vfp_ok } */
+/* { dg-require-effective-target arm_neon_h_ok } */
 /* { dg-options "-O2" } */
-/* { dg-add-options arm_vfp } */
+/* { dg-add-options arm_neon_h } */
 
 extern __simd64_int8_t a, b;
 
@@ -13,4 +13,3 @@ foo (__simd128_int16_t *p)
   *p = (__simd128_int16_t)__builtin_neon_vaddlsv8qi (a, b); /* { dg-error "You must enable NEON instructions .*" } */
 
 }
-

gcc/testsuite/gcc.target/arm/attr-neon-fp16.c

@@ -1,8 +1,8 @@
 /* { dg-do compile } */
 /* { dg-skip-if "-mpure-code supports M-profile only and without Neon" { *-*-* } { "-mpure-code" } } */
-/* { dg-require-effective-target arm_fp_ok } */
+/* { dg-require-effective-target arm_neon_h_ok } */
 /* { dg-options "-mfp16-format=ieee" } */
-/* { dg-add-options arm_fp } */
+/* { dg-add-options arm_neon_h } */
 
 #include "arm_neon.h"
 

gcc/testsuite/gcc.target/arm/attr-neon2.c

@@ -1,8 +1,7 @@
 /* { dg-do compile } */
-/* { dg-require-effective-target arm_neon_ok } */
-/* { dg-require-effective-target arm_fp_ok } */
+/* { dg-require-effective-target arm_neon_h_ok } */
 /* { dg-options "-Ofast" } */
-/* { dg-add-options arm_fp } */
+/* { dg-add-options arm_neon_h } */
 
 /* Reset fpu to a value compatible with the next pragmas.  */
 #pragma GCC target ("fpu=vfp")

gcc/testsuite/lib/target-supports.exp

@@ -5127,7 +5127,7 @@ proc add_options_for_arm_fp { flags } {
 proc check_effective_target_arm_libc_fp_abi_ok_nocache { } {
     global et_arm_libc_fp_abi_flags
     set et_arm_libc_fp_abi_flags ""
-    if { [check_effective_target_arm32] } {
+    if { [istarget arm*-*-*] } {
 	foreach flags {"-mfloat-abi=hard" "-mfloat-abi=softfp"} {
 	    if { [check_no_compiler_messages_nocache arm_libc_fp_abi_ok object {
 		#include <stdint.h>
@@ -5155,6 +5155,57 @@ proc add_options_for_arm_libc_fp_abi { flags } {
     return "$flags $et_arm_libc_fp_abi_flags"
 }
 
+# Try to find the minimal set of flags needed to make the header file
+# arm_neon.h compatible with this compilation.  This is complicated due
+# to the fact that this header doesn't work properly on m-profile cores
+# and also won't work correctly if the wrong floating-point ABI is used
+# on the platform (since arm_neon.h can include stdint.h, which on Linux
+# will pull in stub headers that aren't installed).
+# Note: This will not necessarily enable Neon instructions, just provide
+# something where the header will not cause errors.
+
+proc check_effective_target_arm_neon_h_ok_nocache { } {
+    # none-arm or thumb1 cannot support neon, so there's no point in
+    # looking further.
+    if { [istarget arm*-*-*] } {
+	global et_arm_neon_h_flags
+	set base_flags [add_options_for_arm_libc_fp_abi ""]
+	foreach flags {"" "-mfpu=auto" "-marm" "-marm -mfpu=auto" \
+			   "-mcpu=unset -march=armv7-a+fp -mfpu=auto" } {
+	    if { [check_no_compiler_messages_nocache arm_neon_h_ok assembly {
+		#if __ARM_ARCH < 5
+		#error architecture too low for FP
+		#endif
+		#if __ARM_ARCH < 7
+		#if !defined(__arm__) || (defined(__thumb__) && !defined(__thumb2__))
+		#error incompatible arch or mode
+		#endif
+		#endif
+		#if __ARM_ARCH_PROFILE == 'M'
+		#error incompatible profile
+		#endif
+	    } "$base_flags $flags" ] } {
+		set et_arm_neon_h_flags "$base_flags $flags"
+		return 1
+	    }
+	}
+    }
+    return 0
+}
+
+proc check_effective_target_arm_neon_h_ok { } {
+    return [check_cached_effective_target arm_neon_h_ok \
+		check_effective_target_arm_neon_h_ok_nocache]
+}
+
+proc add_options_for_arm_neon_h { flags } {
+    if { ! [check_effective_target_arm_neon_h_ok] } {
+	return "$flags"
+    }
+    global et_arm_neon_h_flags
+    return "$flags $et_arm_neon_h_flags"
+}
+
 # Return 1 if this is an ARM target defining __ARM_FP with
 # double-precision support. We may need -mfloat-abi=softfp or
 # equivalent options.  Some multilibs may be incompatible with these