re PR tree-optimization/92558 (Miscompare of 554.roms_r with -Ofast…

re PR tree-optimization/92558 (Miscompare of 554.roms_r with -Ofast -march=znver2 -flto since r278289)

2019-11-18  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/92558
	* tree-vect-loop.c (vect_create_epilog_for_reduction): When
	reducting the width of a reduction vector def update new_phis.

	* gcc.dg/vect/pr92558.c: New testcase.

From-SVN: r278400

gcc/ChangeLog

+2019-11-18  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/92558
+	* tree-vect-loop.c (vect_create_epilog_for_reduction): When
+	reducting the width of a reduction vector def update new_phis.
+
 2019-11-18  Szabolcs Nagy  <szabolcs.nagy@arm.com>
 
 	* configure.ac (gcc_cv_target_ldbl128): Set for powerpc*-*-linux-musl*

gcc/testsuite/ChangeLog

+2019-11-18  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/92558
+	* gcc.dg/vect/pr92558.c: New testcase.
+
 2019-11-18  Martin Liska  <mliska@suse.cz>
 
 	PR ipa/92529

gcc/testsuite/gcc.dg/vect/pr92558.c

+/* { dg-additional-options "-mavx2" { target avx2_runtime } } */
+
+void __attribute__((noipa))
+foo (int * __restrict wsum, int * __restrict cff, int * __restrict weight)
+{
+  for (int i = 0; i < 16; ++i)
+    {
+      *wsum += weight[2*i+0];
+      *cff += weight[2*i+1];
+    }
+}
+
+int main()
+{
+  int weight[32];
+  for (int i = 0; i < 32; ++i)
+    weight[i] = i;
+  int wsum = 0, cff = 0;
+  foo (&wsum, &cff, weight);
+  if (wsum != 240 || cff != 256)
+    __builtin_abort ();
+  return 0;
+}

gcc/tree-vect-loop.c

@@ -5198,6 +5198,7 @@ vect_create_epilog_for_reduction (stmt_vec_info stmt_info,
 	  new_temp = make_ssa_name (vectype1);
 	  epilog_stmt = gimple_build_assign (new_temp, code, dst1, dst2);
 	  gsi_insert_before (&exit_gsi, epilog_stmt, GSI_SAME_STMT);
+	  new_phis[0] = epilog_stmt;
 	}
 
       if (reduce_with_shift && !slp_reduc)