vect_analyze_loop_operations was calling vectorizable_live_operation
for all live-out phis, which led to a bogus ncopies calculation in
the pure SLP case. I think v_a_l_o should only be passing phis
that are vectorised using normal loop vectorisation, since
vect_slp_analyze_node_operations handles the SLP side (and knows
the correct slp_index and slp_node arguments to pass in, via
vect_analyze_stmt).
With that fixed we hit an older bug that vectorizable_live_operation
didn't handle live-out SLP inductions. Fixed by using gimple_phi_result
rather than gimple_get_lhs for phis.
Tested on aarch64-linux-gnu. OK to install?
Richard
2018-01-16 Richard Sandiford <richard.sandif...@linaro.org>
gcc/
PR tree-optimization/83857
* tree-vect-loop.c (vect_analyze_loop_operations): Don't call
vectorizable_live_operation for pure SLP statements.
(vectorizable_live_operation): Handle PHIs.
gcc/testsuite/
PR tree-optimization/83857
* gcc.dg/vect/pr83857.c: New test.
Index: gcc/tree-vect-loop.c
===================================================================
--- gcc/tree-vect-loop.c 2018-01-13 18:02:00.950360196 +0000
+++ gcc/tree-vect-loop.c 2018-01-16 13:24:33.022528019 +0000
@@ -1851,7 +1851,10 @@ vect_analyze_loop_operations (loop_vec_i
ok = vectorizable_reduction (phi, NULL, NULL, NULL, NULL);
}
- if (ok && STMT_VINFO_LIVE_P (stmt_info))
+ /* SLP PHIs are tested by vect_slp_analyze_node_operations. */
+ if (ok
+ && STMT_VINFO_LIVE_P (stmt_info)
+ && !PURE_SLP_STMT (stmt_info))
ok = vectorizable_live_operation (phi, NULL, NULL, -1, NULL);
if (!ok)
@@ -8217,7 +8220,11 @@ vectorizable_live_operation (gimple *stm
gcc_assert (!LOOP_VINFO_FULLY_MASKED_P (loop_vinfo));
/* Get the correct slp vectorized stmt. */
- vec_lhs = gimple_get_lhs (SLP_TREE_VEC_STMTS (slp_node)[vec_entry]);
+ gimple *vec_stmt = SLP_TREE_VEC_STMTS (slp_node)[vec_entry];
+ if (gphi *phi = dyn_cast <gphi *> (vec_stmt))
+ vec_lhs = gimple_phi_result (phi);
+ else
+ vec_lhs = gimple_get_lhs (vec_stmt);
/* Get entry to use. */
bitstart = bitsize_int (vec_index);
Index: gcc/testsuite/gcc.dg/vect/pr83857.c
===================================================================
--- /dev/null 2018-01-15 18:48:25.844002736 +0000
+++ gcc/testsuite/gcc.dg/vect/pr83857.c 2018-01-16 13:24:33.021528058 +0000
@@ -0,0 +1,30 @@
+/* { dg-do run } */
+/* { dg-additional-options "-ffast-math" } */
+
+#define N 100
+
+double __attribute__ ((noinline, noclone))
+f (double *x, double y)
+{
+ double a = 0;
+ for (int i = 0; i < N; ++i)
+ {
+ a += y;
+ x[i * 2] += a;
+ x[i * 2 + 1] += a;
+ }
+ return a - y;
+}
+
+double x[N * 2];
+
+int
+main (void)
+{
+ if (f (x, 5) != (N - 1) * 5)
+ __builtin_abort ();
+ return 0;
+}
+
+/* { dg-final { scan-tree-dump "Loop contains only SLP stmts" "vect" { target
vect_double } } } */
+/* { dg-final { scan-tree-dump "vectorized 1 loops" "vect" { target
vect_double } } } */
