[PATCH][ARM] PR target/71056: Don't use vectorized builtins when NEON is not available

[Kyrill Tkachov]

Hi all,

In this PR a NEON builtin is introduced during SLP vectorisation even when NEON 
is not available
because arm_builtin_vectorized_function is missing an appropriate check in the 
BSWAP handling code.

Then during expand when we try to expand the NEON builtin the code in 
arm_expand_neon_builtin rightly
throws an error telling the user to enable NEON, even though the testcase 
doesn't use any intrinsics.

This patch fixes the bug by bailing out early if !TARGET_NEON. This allows us 
to remove a redundant
TARGET_NEON check further down in the function as well.

Bootstrapped and tested on arm-none-linux-gnueabihf.
Ok for trunk?

This appears on GCC 6 as well.
On older branches the test failure doesn't trigger but the logic looks buggy 
anyway.
Ok for the branches as well if testing is clean?

Thanks,
Kyrill

2016-05-11  Kyrylo Tkachov  <kyrylo.tkac...@arm.com>

    PR target/71056
    * config/arm/arm-builtins.c (arm_builtin_vectorized_function): Return
    NULL_TREE early if NEON is not available.  Remove now redundant check
    in ARM_CHECK_BUILTIN_MODE.

2016-05-11  Kyrylo Tkachov  <kyrylo.tkac...@arm.com>

    PR target/71056
    * gcc.target/arm/pr71056.c: New test.

diff --git a/gcc/config/arm/arm-builtins.c b/gcc/config/arm/arm-builtins.c
index 90fb40fed24cd31ed7f718664fc9b45e58c3cfa8..68b2839879f78e8d819444fbc11d2a91f8d6279a 100644
--- a/gcc/config/arm/arm-builtins.c
+++ b/gcc/config/arm/arm-builtins.c
@@ -2861,6 +2861,10 @@ arm_builtin_vectorized_function (unsigned int fn, tree type_out, tree type_in)
   int in_n, out_n;
   bool out_unsigned_p = TYPE_UNSIGNED (type_out);
 
+  /* Can't provide any vectorized builtins when we can't use NEON.  */
+  if (!TARGET_NEON)
+    return NULL_TREE;
+
   if (TREE_CODE (type_out) != VECTOR_TYPE
       || TREE_CODE (type_in) != VECTOR_TYPE)
     return NULL_TREE;
@@ -2875,7 +2879,7 @@ arm_builtin_vectorized_function (unsigned int fn, tree type_out, tree type_in)
    NULL_TREE is returned if no such builtin is available.  */
 #undef ARM_CHECK_BUILTIN_MODE
 #define ARM_CHECK_BUILTIN_MODE(C)    \
-  (TARGET_NEON && TARGET_FPU_ARMV8   \
+  (TARGET_FPU_ARMV8   \
    && flag_unsafe_math_optimizations \
    && ARM_CHECK_BUILTIN_MODE_1 (C))
 
diff --git a/gcc/testsuite/gcc.target/arm/pr71056.c b/gcc/testsuite/gcc.target/arm/pr71056.c
new file mode 100644
index 0000000000000000000000000000000000000000..136754eb13c4c4f8f840001d5520cf27f3c57461
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/pr71056.c
@@ -0,0 +1,32 @@
+/* PR target/71056.  */
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_vfp3_ok } */
+/* { dg-options "-O3 -mfpu=vfpv3" } */
+
+/* Check that compiling for a non-NEON target doesn't try to introduce
+   a NEON vectorized builtin.  */
+
+extern char *buff;
+int f2 ();
+struct T1
+{
+  int reserved[2];
+  unsigned int ip;
+  unsigned short cs;
+  unsigned short rsrv2;
+};
+void
+f3 (const char *p)
+{
+  struct T1 x;
+  __builtin_memcpy (&x, p, sizeof (struct T1));
+  x.reserved[0] = __builtin_bswap32 (x.reserved[0]);
+  x.reserved[1] = __builtin_bswap32 (x.reserved[1]);
+  x.ip = __builtin_bswap32 (x.ip);
+  x.cs = x.cs << 8 | x.cs >> 8;
+  x.rsrv2 = x.rsrv2 << 8 | x.rsrv2 >> 8;
+  if (f2 ())
+    {
+      __builtin_memcpy (buff, "\n", 1);
+    }
+}