re PR tree-optimization/40351 (ice in generate_subtree_copies for Linux kernel build)

2009-06-09  Martin Jambor  <mjambor@suse.cz>

	PR tree-optimization/40351
	* tree-sra.c (propagate_subacesses_accross_link): Check that a refrence
	to a potential artifical subaccess can be constructed.

	* testsuite/gcc.c-torture/compile/pr40351.c: New file.

From-SVN: r148315

gcc/ChangeLog

+2009-06-09  Martin Jambor  <mjambor@suse.cz>
+
+	PR tree-optimization/40351
+	* tree-sra.c (propagate_subacesses_accross_link): Check that a refrence
+	to a potential artifical subaccess can be constructed.
+
 2009-06-08  Kaz Kojima  <kkojima@gcc.gnu.org>
 
 	* config/sh/sh-protos.h (sh_optimization_options): Declare.

gcc/testsuite/ChangeLog

+2009-06-09  Martin Jambor  <mjambor@suse.cz>
+
+	* testsuite/gcc.c-torture/compile/pr40351.c: New file.
+
 2009-06-09  Olivier Hainque  <hainque@adacore.com>
 
 	* gnat.dg/align_max.adb: New test.

gcc/testsuite/gcc.c-torture/compile/pr40351.c

+/* PR tree-optimizations/40351 */
+
+struct IO_APIC_route_entry {
+    unsigned int vector : 8;
+    unsigned int delivery_mode : 1;
+    unsigned int mask : 1;
+    unsigned int __reserved_2 : 15;
+    unsigned int __reserved_3 : 8;
+} __attribute__ ((packed));
+union entry_union {
+    struct {
+        unsigned int w1, w2;
+    };
+    struct IO_APIC_route_entry entry;
+};
+unsigned int io_apic_read(void);
+struct IO_APIC_route_entry ioapic_read_entry(void)
+{
+  union entry_union eu;
+  eu.w1 = io_apic_read();
+  return eu.entry;
+}

gcc/tree-sra.c

@@ -1544,6 +1544,13 @@ propagate_subacesses_accross_link (struct access *lacc, struct access *racc)
 	  continue;
 	}
 
+      /* If a (part of) a union field in on the RHS of an assignment, it can
+	 have sub-accesses which do not make sense on the LHS (PR 40351).
+	 Check that this is not the case.  */
+      if (!build_ref_for_offset (NULL, TREE_TYPE (lacc->base), norm_offset,
+				 rchild->type, false))
+	continue;
+
       new_acc = create_artificial_child_access (lacc, rchild, norm_offset);
       if (racc->first_child)
 	propagate_subacesses_accross_link (new_acc, rchild);