re PR tree-optimization/71483 (g++ ICE at -O3 on valid code on x86_64-linux-gnu…

re PR tree-optimization/71483 (g++ ICE at -O3 on valid code on x86_64-linux-gnu with “Floating point exception”)

2016-06-15  Alan Hayward  <alan.hayward@arm.com>

gcc/
	PR tree-optimization/71483
	* tree-vect-loop.c (vectorizable_live_operation): Pick correct index
	for slp

testsuite/
	PR tree-optimization/71483
	* g++.dg/vect/pr71483.c: New

From-SVN: r237483

gcc/ChangeLog

+2016-06-15  Alan Hayward  <alan.hayward@arm.com>
+
+	PR tree-optimization/71483
+	* tree-vect-loop.c (vectorizable_live_operation): Pick correct index
+	for slp
+
 2016-06-15  Martin Liska  <mliska@suse.cz>
 
 	* predict.c (tree_predict_by_opcode): Call predict_edge_def

gcc/testsuite/ChangeLog

+2016-06-15  Alan Hayward  <alan.hayward@arm.com>
+
+	PR tree-optimization/71483
+	* g++.dg/vect/pr71483.c: New
+
 2016-06-15  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/70202

gcc/testsuite/g++.dg/vect/pr71483.c

+/* { dg-do compile } */
+int b, c, d;
+short *e;
+void fn1() {
+  for (; b; b--) {
+    d = *e >> 2;
+    *e++ = d;
+    c = *e;
+    *e++ = d;
+  }
+}

gcc/tree-vect-loop.c

@@ -6368,24 +6368,20 @@ vectorizable_live_operation (gimple *stmt,
 
       int num_scalar = SLP_TREE_SCALAR_STMTS (slp_node).length ();
       int num_vec = SLP_TREE_NUMBER_OF_VEC_STMTS (slp_node);
-      int scalar_per_vec = num_scalar / num_vec;
 
-      /* There are three possibilites here:
-	 1: All scalar stmts fit in a single vector.
-	 2: All scalar stmts fit multiple times into a single vector.
-	    We must choose the last occurence of stmt in the vector.
-	 3: Scalar stmts are split across multiple vectors.
-	    We must choose the correct vector and mod the lane accordingly.  */
+      /* Get the last occurrence of the scalar index from the concatenation of
+	 all the slp vectors. Calculate which slp vector it is and the index
+	 within.  */
+      int pos = (num_vec * nunits) - num_scalar + slp_index;
+      int vec_entry = pos / nunits;
+      int vec_index = pos % nunits;
 
       /* Get the correct slp vectorized stmt.  */
-      int vec_entry = slp_index / scalar_per_vec;
       vec_lhs = gimple_get_lhs (SLP_TREE_VEC_STMTS (slp_node)[vec_entry]);
 
       /* Get entry to use.  */
-      bitstart = build_int_cst (unsigned_type_node,
-				scalar_per_vec - (slp_index % scalar_per_vec));
+      bitstart = build_int_cst (unsigned_type_node, vec_index);
       bitstart = int_const_binop (MULT_EXPR, bitsize, bitstart);
-      bitstart = int_const_binop (MINUS_EXPR, vec_bitsize, bitstart);
     }
   else
     {