2010-12-02  Bernd Schmidt  <bernds@codesourcery.com>

	Issue #10089

	gcc/
	* expr.c (store_field): Avoid a direct store if the mode is larger
	than the size of the bit field.
	* stor-layout.c (layout_decl): If flag_strict_volatile_bitfields,
	treat non-volatile bit fields like volatile ones.
	* toplev.c (process_options): Disallow combination of
	-fstrict-volatile-bitfields and ABI versions less than 2.
	* config/arm/arm.c (arm_option_override): Don't enable
	flag_strict_volatile_bitfields if the ABI version is less than 2.
	* config/h8300/h8300.c (h8300_option_override): Likewise.
	* config/rx/rx.c (rx_option_override): Likewise.
	* config/m32c/m32c.c (m32c_option_override): Likewise.
	* config/sh/sh.c (sh_option_override): Likewise.

	gcc/testsuite/
	* gcc.target/arm/volatile-bitfields-4.c: New test.
	* c-c++-common/abi-bf.c: New test.

=== modified file 'gcc/config/arm/arm.c'
--- old/gcc/config/arm/arm.c	2010-12-10 15:30:47 +0000
+++ new/gcc/config/arm/arm.c	2010-12-10 15:34:19 +0000
@@ -1934,7 +1934,8 @@
     set_param_value ("gcse-unrestricted-cost", 2);
 
   /* ARM EABI defaults to strict volatile bitfields.  */
-  if (TARGET_AAPCS_BASED && flag_strict_volatile_bitfields < 0)
+  if (TARGET_AAPCS_BASED && flag_strict_volatile_bitfields < 0
+      && abi_version_at_least(2))
     flag_strict_volatile_bitfields = 1;
 
   /* Register global variables with the garbage collector.  */

=== modified file 'gcc/config/h8300/h8300.c'
--- old/gcc/config/h8300/h8300.c	2010-11-04 12:43:52 +0000
+++ new/gcc/config/h8300/h8300.c	2010-12-10 15:34:19 +0000
@@ -405,7 +405,7 @@
     }
 
   /* This target defaults to strict volatile bitfields.  */
-  if (flag_strict_volatile_bitfields < 0)
+  if (flag_strict_volatile_bitfields < 0 && abi_version_at_least(2))
     flag_strict_volatile_bitfields = 1;
 }
 

=== modified file 'gcc/config/m32c/m32c.c'
--- old/gcc/config/m32c/m32c.c	2010-11-04 12:43:52 +0000
+++ new/gcc/config/m32c/m32c.c	2010-12-10 15:34:19 +0000
@@ -430,7 +430,7 @@
     flag_ivopts = 0;
 
   /* This target defaults to strict volatile bitfields.  */
-  if (flag_strict_volatile_bitfields < 0)
+  if (flag_strict_volatile_bitfields < 0 && abi_version_at_least(2))
     flag_strict_volatile_bitfields = 1;
 }
 

=== modified file 'gcc/config/rx/rx.c'
--- old/gcc/config/rx/rx.c	2010-11-04 12:43:52 +0000
+++ new/gcc/config/rx/rx.c	2010-12-10 15:34:19 +0000
@@ -2191,7 +2191,7 @@
 rx_option_override (void)
 {
   /* This target defaults to strict volatile bitfields.  */
-  if (flag_strict_volatile_bitfields < 0)
+  if (flag_strict_volatile_bitfields < 0 && abi_version_at_least(2))
     flag_strict_volatile_bitfields = 1;
 }
 

=== modified file 'gcc/config/sh/sh.c'
--- old/gcc/config/sh/sh.c	2010-11-04 12:43:52 +0000
+++ new/gcc/config/sh/sh.c	2010-12-10 15:34:19 +0000
@@ -952,7 +952,7 @@
     sh_fix_range (sh_fixed_range_str);
 
   /* This target defaults to strict volatile bitfields.  */
-  if (flag_strict_volatile_bitfields < 0)
+  if (flag_strict_volatile_bitfields < 0 && abi_version_at_least(2))
     flag_strict_volatile_bitfields = 1;
 }
 

=== modified file 'gcc/expr.c'
--- old/gcc/expr.c	2010-11-04 12:43:52 +0000
+++ new/gcc/expr.c	2010-12-10 15:34:19 +0000
@@ -5848,6 +5848,8 @@
 		|| bitpos % GET_MODE_ALIGNMENT (mode))
 	       && SLOW_UNALIGNED_ACCESS (mode, MEM_ALIGN (target)))
 	      || (bitpos % BITS_PER_UNIT != 0)))
+      || (bitsize >= 0 && mode != BLKmode
+	  && GET_MODE_BITSIZE (mode) > bitsize)
       /* If the RHS and field are a constant size and the size of the
 	 RHS isn't the same size as the bitfield, we must use bitfield
 	 operations.  */

=== modified file 'gcc/stor-layout.c'
--- old/gcc/stor-layout.c	2010-11-26 12:03:32 +0000
+++ new/gcc/stor-layout.c	2010-12-10 15:34:19 +0000
@@ -621,12 +621,13 @@
 	  /* See if we can use an ordinary integer mode for a bit-field.
 	     Conditions are: a fixed size that is correct for another mode,
 	     occupying a complete byte or bytes on proper boundary,
-	     and not volatile or not -fstrict-volatile-bitfields.  */
+	     and not -fstrict-volatile-bitfields.  If the latter is set,
+	     we unfortunately can't check TREE_THIS_VOLATILE, as a cast
+	     may make a volatile object later.  */
 	  if (TYPE_SIZE (type) != 0
 	      && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
 	      && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT
-	      && !(TREE_THIS_VOLATILE (decl)
-		   && flag_strict_volatile_bitfields > 0))
+	      && flag_strict_volatile_bitfields <= 0)
 	    {
 	      enum machine_mode xmode
 		= mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);

=== added file 'gcc/testsuite/c-c++-common/abi-bf.c'
--- old/gcc/testsuite/c-c++-common/abi-bf.c	1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/c-c++-common/abi-bf.c	2010-12-10 15:34:19 +0000
@@ -0,0 +1,3 @@
+/* { dg-warning "incompatible" } */
+/* { dg-do compile } */
+/* { dg-options "-fstrict-volatile-bitfields -fabi-version=1" } */

=== added file 'gcc/testsuite/gcc.target/arm/volatile-bitfields-4.c'
--- old/gcc/testsuite/gcc.target/arm/volatile-bitfields-4.c	1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/gcc.target/arm/volatile-bitfields-4.c	2010-12-10 15:34:19 +0000
@@ -0,0 +1,30 @@
+/* { dg-require-effective-target arm_eabi } */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-times "ldr\[\\t \]+\[^\n\]*,\[\\t \]*\\\[\[^\n\]*\\\]" 2 } } */
+/* { dg-final { scan-assembler-times "str\[\\t \]+\[^\n\]*,\[\\t \]*\\\[\[^\n\]*\\\]" 2 } } */
+/* { dg-final { scan-assembler-not "strb" } } */
+
+struct thing {
+  unsigned a: 8;
+  unsigned b: 8;
+  unsigned c: 8;
+  unsigned d: 8;
+};
+
+struct thing2 {
+  volatile unsigned a: 8;
+  volatile unsigned b: 8;
+  volatile unsigned c: 8;
+  volatile unsigned d: 8;
+};
+
+void test1(volatile struct thing *t)
+{
+  t->a = 5;
+}
+
+void test2(struct thing2 *t)
+{
+  t->a = 5;
+}

=== modified file 'gcc/toplev.c'
--- old/gcc/toplev.c	2010-03-31 01:44:10 +0000
+++ new/gcc/toplev.c	2010-12-10 15:34:19 +0000
@@ -1851,6 +1851,13 @@
     sorry ("Graphite loop optimizations cannot be used");
 #endif
 
+  if (flag_strict_volatile_bitfields > 0 && !abi_version_at_least (2))
+    {
+      warning (0, "-fstrict-volatile-bitfield disabled; "
+	       "it is incompatible with ABI versions < 2");
+      flag_strict_volatile_bitfields = 0;
+    }
+
   /* Unrolling all loops implies that standard loop unrolling must also
      be done.  */
   if (flag_unroll_all_loops)

