tree-optimization/110443 - prevent SLP splat of gathers

The following prevents non-grouped load SLP in case the element
to splat is from a gather operation.  While it should be possible
to support this it is not similar to the single element interleaving
case I was trying to mimic here.

	PR tree-optimization/110443
	* tree-vect-slp.cc (vect_build_slp_tree_1): Reject non-grouped
	gather loads.

	* gcc.dg/torture/pr110443.c: New testcase.

diff --git a/gcc/testsuite/gcc.dg/torture/pr110443.c b/gcc/testsuite/gcc.dg/torture/pr110443.c
new file mode 100644 (file)
index 0000000..61cf705
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr110443.c
@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+
+typedef struct {
+  float real;
+  float imag;
+} complex_t;
+extern unsigned char fftorder[];
+float *a52_imdct_256_data;
+int a52_imdct_256_i, a52_imdct_256_k;
+float a52_imdct_256_b_r;
+void a52_imdct_256()
+{
+  complex_t buf1[64];
+  a52_imdct_256_i = 0;
+  for (; a52_imdct_256_i < 64; a52_imdct_256_i++) {
+    a52_imdct_256_k = fftorder[a52_imdct_256_i];
+    buf1[a52_imdct_256_i].real = buf1[a52_imdct_256_i].imag =
+        a52_imdct_256_data[a52_imdct_256_k];
+  }
+  a52_imdct_256_b_r = buf1[0].real * buf1[0].imag;
+}

diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index 8cb1ac1f3194b2c7356a0e3cfb5c8ee5ec4663c0..355d078d66ef698f636da8b5a593c57c36c127a6 100644 (file)
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -1291,7 +1291,8 @@ vect_build_slp_tree_1 (vec_info *vinfo, unsigned char *swap,
                 vectorization.  For loop vectorization we can handle
                 splats the same we handle single element interleaving.  */
              && (is_a <bb_vec_info> (vinfo)
-                 || stmt_info != first_stmt_info))
+                 || stmt_info != first_stmt_info
+                 || STMT_VINFO_GATHER_SCATTER_P (stmt_info)))
            {
              /* Not grouped load.  */
              if (dump_enabled_p ())