Re: [RFC PATCH] Gather vectorization (PR tree-optimization/50789)

[Jakub Jelinek <jakub at redhat dot com>]

On Mon, Oct 31, 2011 at 03:23:32PM +0100, Jakub Jelinek wrote:
> Would be nice to cut down slightly this testcase into just one or two loops
> that are vectorized and turn it into a runtime testcase which verifies
> the vectorization was correct.

Here is one such testcase (though, in your case there are no loads
for the indexes, on the other side you have 3 of the IVs each multiplied
by some loop invariant and all added together.  Though, on the other
side in your case there are far more expressions.

2011-10-31  Jakub Jelinek  <jakub@redhat.com>

	* gcc.target/i386/avx2-gather-4.c: New test.

--- gcc/testsuite/gcc.target/i386/avx2-gather-4.c.jj	2011-10-31 15:58:57.000000000 +0100
+++ gcc/testsuite/gcc.target/i386/avx2-gather-4.c	2011-10-31 15:59:44.000000000 +0100
@@ -0,0 +1,38 @@
+/* { dg-do run } */
+/* { dg-require-effective-target avx2 } */
+/* { dg-options "-O3 -mavx2" } */
+
+#include "avx2-check.h"
+
+#define N 1024
+int a[N], b[N], c[N], d[N];
+
+__attribute__((noinline, noclone)) void
+foo (float *__restrict p, float *__restrict q, float *__restrict r,
+     long s1, long s2, long s3)
+{
+  int i;
+  for (i = 0; i < N; i++)
+    p[i] = q[a[i] * s1 + b[i] * s2 + s3] * r[c[i] * s1 + d[i] * s2 + s3];
+}
+
+static void
+avx2_test (void)
+{
+  int i;
+  float e[N], f[N], g[N];
+  for (i = 0; i < N; i++)
+    {
+      a[i] = (i * 7) & (N / 8 - 1);
+      b[i] = (i * 13) & (N / 8 - 1);
+      c[i] = (i * 23) & (N / 8 - 1);
+      d[i] = (i * 5) & (N / 8 - 1);
+      e[i] = 16.5 + i;
+      f[i] = 127.5 - i;
+    }
+  foo (g, e, f, 3, 2, 4);
+  for (i = 0; i < N; i++)
+    if (g[i] != (float) ((20.5 + a[i] * 3 + b[i] * 2)
+			 * (123.5 - c[i] * 3 - d[i] * 2)))
+      abort ();
+}


	Jakub