[PATCH]: fix for PR middle-end/38250

[Tomas Bily]

Hi,

The PR is caused by two problems:

In tree-loop-distribution.c (generate_memset_zero): 

1. It can be DR_STEP(dr) NULL. But it is passed into fold_build2 that
expect two non null expressions.

2. If program flow goes to end: due to goto then temporary variables created
during force_gimple_operand are added to referenced vars. But this variables
have not def bb. So later checks fails.

This patch add check for DR_STEP and remove newly generated stmts if
generating of memset fails.

Tested and bootsraped on x86_64-unknown-linux-gnu.

OK for mainline ?

Greetings
Tomas

Changelog:

	PR middle-end/38250
	* tree-loop-distribution.c (remove_stmts): New function.
	(generate_memset_zero): Checks if DR_STEP(de) is NULL. Remove generated
	stmts if checks fails.

Index: tree-loop-distribution.c
===================================================================
--- tree-loop-distribution.c	(revision 142159)
+++ tree-loop-distribution.c	(working copy)
@@ -216,6 +216,21 @@ generate_loops_for_partition (struct loo
   return true;
 }
 
+/* Remove stmts in a list.  */
+
+static void
+remove_stmts (gimple_seq stmt_list)
+{
+  gimple_stmt_iterator i;
+
+  for (i = gsi_start (stmt_list); ; gsi_next (&i))
+    {
+      gsi_remove (&i, true);
+      if (gsi_end_p (i))
+	  break;
+    }
+}
+
 /* Generate a call to memset.  Return true when the operation succeeded.  */
 
 static bool
@@ -240,6 +255,12 @@ generate_memset_zero (gimple stmt, tree 
   DR_REF (dr) = op0;
   dr_analyze_innermost (dr);
 
+  if (!DR_STEP (dr))
+    {
+      remove_stmts (stmt_list);
+      goto end;
+    }
+
   /* Test for a positive stride, iterating over every element.  */
   if (integer_zerop (fold_build2 (MINUS_EXPR, integer_type_node, DR_STEP (dr),
 				  TYPE_SIZE_UNIT (TREE_TYPE (op0)))))
@@ -263,7 +284,10 @@ generate_memset_zero (gimple stmt, tree 
 			       DR_BASE_ADDRESS (dr), addr_base);
     }
   else
-    goto end;
+      {
+        remove_stmts (stmt_list);
+        goto end;
+      }
 
   mem = force_gimple_operand (addr_base, &stmts, true, NULL);
   gimple_seq_add_seq (&stmt_list, stmts);
Index: testsuite/gcc.dg/tree-ssa/pr38250.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/pr38250.c	(revision 0)
+++ testsuite/gcc.dg/tree-ssa/pr38250.c	(revision 0)
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -ftree-loop-distribution" } */
+
+typedef long unsigned int size_t;
+typedef struct   {
+          long dat[2];
+} gsl_complex_long_double;
+typedef struct {
+ size_t size;
+ size_t stride;
+ long *data;
+} gsl_vector_complex_long_double;
+
+void gsl_vector_complex_long_double_set_zero (gsl_vector_complex_long_double * v) 
+{
+ long * const data = v->data;
+ const size_t n = v->size;
+ const size_t stride = v->stride;
+ const gsl_complex_long_double zero = { { 0,0} } ;
+ size_t i;
+ for (i = 0; i < n; i++)     
+  *(gsl_complex_long_double *) (data + 2 * i * stride) = zero;
+}
+