Add a testcase for PR target/96827

Add a testcase for PR target/96827 which was fixed by r11-3559:

commit 97b798d80baf945ea28236eef3fa69f36626b579
Author: Joel Hutton <joel.hutton@arm.com>
Date:   Wed Sep 30 15:08:13 2020 +0100

    [SLP][VECT] Add check to fix 96837

	PR target/96827
	* gcc.target/i386/pr96827.c: New test.

1 files changed, 41 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.target/i386/pr96827.c b/gcc/testsuite/gcc.target/i386/pr96827.c
new file mode 100644
index 0000000..309e9e8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr96827.c
@@ -0,0 +1,41 @@
+/* { dg-do run { target sse2_runtime } } */
+/* { dg-options "-O3 -msse2 -mfpmath=sse" } */
+
+typedef unsigned short int __uint16_t;
+typedef unsigned int __uint32_t;
+typedef __uint16_t uint16_t;
+typedef __uint32_t uint32_t;
+typedef int __v4si __attribute__ ((__vector_size__ (16)));
+typedef long long __m128i __attribute__ ((__vector_size__ (16), __may_alias__));
+extern __inline void __attribute__((__gnu_inline__, __always_inline__, __artificial__))
+_mm_store_si128 (__m128i *__P, __m128i __B)
+{
+  *__P = __B;
+}
+extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
+_mm_set_epi32 (int __q3, int __q2, int __q1, int __q0)
+{
+  return __extension__ (__m128i)(__v4si){ __q0, __q1, __q2, __q3 };
+}
+typedef uint16_t u16;
+typedef uint32_t u32;
+extern int printf (const char *__restrict __format, ...);
+void do_the_thing(u32 idx, __m128i *dude)
+{
+ u32 dude_[4] = { idx+0, idx+2, idx+4, idx+6 };
+ for (u32 i = 0; i < 3; ++i)
+  if (dude_[i] == 1234)
+   dude_[i]--;
+ *dude = _mm_set_epi32(dude_[0], dude_[1], dude_[2], dude_[3]);
+}
+int main()
+{
+ __m128i dude;
+ u32 idx = 0;
+ do_the_thing(idx, &dude);
+ __attribute__((aligned(16))) u32 dude_[4];
+ _mm_store_si128((__m128i*)dude_, dude);
+ if (!(6 == dude_[0] && 4 == dude_[1] && 2 == dude_[2] && 0 == dude_[3]))
+   __builtin_abort ();
+ return 0;
+}