avr.c: Add comment on why -fdelete-null-pointer-checks is disabled.

2014-04-24  Vishnu K S  <Vishnu.k_s@atmel.com>

	* gcc/config/avr/avr.c: Add comment on why -fdelete-null-pointer-checks
	is disabled.

2014-04-24  Vishnu K S  <Vishnu.k_s@atmel.com>

	* gcc/testsuite/gcc.dg/tree-ssa/isolate-1.c: Skip test if
	keeps_null_pointer_checks.
	* gcc/testsuite/gcc.dg/tree-ssa/isolate-2.c: Ditto
	* gcc/testsuite/gcc.dg/tree-ssa/isolate-3.c: Ditto
	* gcc/testsuite/gcc.dg/tree-ssa/isolate-4.c: Ditto
	* gcc/testsuite/gcc.dg/tree-ssa/isolate-5.c: Ditto

From-SVN: r209767

gcc/ChangeLog

+2014-04-24  Vishnu K S  <Vishnu.k_s@atmel.com>
+
+	* gcc/config/avr/avr.c: Add comment on why -fdelete-null-pointer-checks
+	is disabled.
+
 2014-04-24  Jakub Jelinek  <jakub@redhat.com>
 
 	* tree.h (OMP_CLAUSE_LINEAR_GIMPLE_SEQ): Define.

gcc/config/avr/avr.c

@@ -290,6 +290,12 @@ avr_to_int_mode (rtx x)
 static void
 avr_option_override (void)
 {
+  /* Disable -fdelete-null-pointer-checks option for AVR target.
+     This option compiler assumes that dereferencing of a null pointer
+     would halt the program.  For AVR this assumption is not true and
+     programs can safely dereference null pointers.  Changes made by this
+     option may not work properly for AVR.  So disable this option. */
+
   flag_delete_null_pointer_checks = 0;
 
   /* caller-save.c looks for call-clobbered hard registers that are assigned

gcc/testsuite/ChangeLog

+2014-04-24  Vishnu K S  <Vishnu.k_s@atmel.com>
+
+	* gcc/testsuite/gcc.dg/tree-ssa/isolate-1.c: Skip test if
+	keeps_null_pointer_checks.
+	* gcc/testsuite/gcc.dg/tree-ssa/isolate-2.c: Ditto 
+	* gcc/testsuite/gcc.dg/tree-ssa/isolate-3.c: Ditto
+	* gcc/testsuite/gcc.dg/tree-ssa/isolate-4.c: Ditto
+	* gcc/testsuite/gcc.dg/tree-ssa/isolate-5.c: Ditto
+
 2014-04-24  Jakub Jelinek  <jakub@redhat.com>
 
 	* c-c++-common/gomp/atomic-16.c: Remove all dg-error directives.

gcc/testsuite/gcc.dg/tree-ssa/isolate-1.c

 
 /* { dg-do compile } */ 
 /* { dg-options "-O2 -fdump-tree-isolate-paths" } */
+/* { dg-skip-if "" keeps_null_pointer_checks } */
 
 
 struct demangle_component

gcc/testsuite/gcc.dg/tree-ssa/isolate-2.c

 /* { dg-do compile } */ 
 /* { dg-options "-O2 -fisolate-erroneous-paths-attribute -fdump-tree-isolate-paths -fdump-tree-phicprop1" } */
+/* { dg-skip-if "" keeps_null_pointer_checks } */
 
 
 int z;

gcc/testsuite/gcc.dg/tree-ssa/isolate-3.c

 /* { dg-do compile } */ 
 /* { dg-options "-O2 -fdump-tree-isolate-paths" } */
+/* { dg-skip-if "" keeps_null_pointer_checks } */
 
 
 typedef long unsigned int size_t;

gcc/testsuite/gcc.dg/tree-ssa/isolate-4.c

 /* { dg-do compile } */ 
 /* { dg-options "-O2 -fisolate-erroneous-paths-attribute -fdump-tree-isolate-paths -fdump-tree-phicprop1" } */
+/* { dg-skip-if "" keeps_null_pointer_checks } */
 
 
 extern void foo(void *) __attribute__ ((__nonnull__ (1)));

gcc/testsuite/gcc.dg/tree-ssa/isolate-5.c

 /* { dg-do compile } */ 
 /* { dg-options "-O2 -fdump-tree-isolate-paths -fdump-tree-optimized" } */
+/* { dg-skip-if "" keeps_null_pointer_checks } */
 
 struct demangle_component
 {