expr.c (store_field): Avoid a direct store if the mode is larger than the size of the bit field.

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.

From-SVN: r182545

gcc/ChangeLog

@@ -1,3 +1,19 @@
+2011-12-20  Bernd Schmidt  <bernds@codesourcery.com>
+
+	PR middle-end/51200
+	* 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.
+
 2011-12-20  Richard Guenther  <rguenther@suse.de>
 
 	PR lto/46796

gcc/config/arm/arm.c

@@ -1989,7 +1989,8 @@ arm_option_override (void)
 			   global_options_set.x_param_values);
 
   /* 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;
 
   /* Enable sw prefetching at -O3 for CPUS that have prefetch, and we have deemed

gcc/config/h8300/h8300.c

@@ -409,7 +409,7 @@ h8300_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;
 }
 

gcc/config/m32c/m32c.c

@@ -417,7 +417,7 @@ m32c_option_override (void)
     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;
 
   /* r8c/m16c have no 16-bit indirect call, so thunks are involved.

gcc/config/rx/rx.c

@@ -2571,7 +2571,7 @@ 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;
 
   rx_override_options_after_change ();

gcc/config/sh/sh.c

@@ -842,7 +842,7 @@ sh_option_override (void)
     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;
 }
 

gcc/expr.c

@@ -6327,6 +6327,8 @@ store_field (rtx target, HOST_WIDE_INT bitsize, HOST_WIDE_INT bitpos,
 		|| 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.  */

gcc/stor-layout.c

@@ -622,12 +622,13 @@ layout_decl (tree decl, unsigned int known_align)
 	  /* 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);

gcc/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2011-12-20  Bernd Schmidt  <bernds@codesourcery.com>
+
+	PR middle-end/51200
+	* gcc.target/arm/volatile-bitfields-4.c: New test.
+	* c-c++-common/abi-bf.c: New test.
+
 2011-12-20  Dodji Seketeli  <dodji@redhat.com>
 
 	PR debug/49951

gcc/testsuite/c-c++-common/abi-bf.c

@@ -0,0 +1,3 @@
+/* { dg-warning "incompatible" } */
+/* { dg-do compile } */
+/* { dg-options "-fstrict-volatile-bitfields -fabi-version=1" } */

gcc/testsuite/gcc.target/arm/volatile-bitfields-4.c

@@ -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;
+}

gcc/toplev.c

@@ -1330,6 +1330,13 @@ process_options (void)
     flag_ira_region
       = optimize_size || !optimize ? IRA_REGION_ONE : IRA_REGION_MIXED;
 
+  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)