* params.h (ALLOW_STORE_DATA_RACES): New.

	* params.def (PARAM_ALLOW_STORE_DATA_RACES): New.
	* Makefile.in (expr.o): Depend on PARAMS_H.
	* machmode.h (get_best_mode): Add argument.
	* fold-const.c (optimize_bit_field_compare): Add argument to
	get_best_mode.
	(fold_truthop): Same.
	* ifcvt.c (noce_emit_move_insn): Add argument to store_bit_field.
	* expr.c (emit_group_store): Same.
	(copy_blkmode_from_reg): Same.
	(write_complex_part): Same.
	(optimize_bitfield_assignment_op): Add argument.
	Add argument to get_best_mode.
	(get_bit_range): New.
	(expand_assignment): Calculate maxbits and pass it down
	accordingly.
	(store_field): New argument.
	(expand_expr_real_2): New argument to store_field.
	Include params.h.
	* expr.h (store_bit_field): New argument.
	* stor-layout.c (get_best_mode): Restrict mode expansion by taking
	into account maxbits.
	* calls.c (store_unaligned_arguments_into_pseudos): New argument
	to store_bit_field.
	* expmed.c (store_bit_field_1): New argument.  Use it.
	(store_bit_field): Same.
	(store_fixed_bit_field): Same.
	(store_split_bit_field): Same.
	(extract_bit_field_1): Pass new argument to get_best_mode.
	(extract_bit_field): Same.
	* stmt.c (store_bit_field): Pass new argument to store_bit_field.
	* doc/invoke.texi: Document parameter allow-store-data-races.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@176824 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 29 insertions, 0 deletions

diff --git a/gcc/testsuite/c-c++-common/cxxbitfields-5.c b/gcc/testsuite/c-c++-common/cxxbitfields-5.c
new file mode 100644
index 00000000000..69e4e1067bf
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cxxbitfields-5.c
@@ -0,0 +1,29 @@
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 --param allow-store-data-races=0" } */
+
+#include <stdlib.h>
+
+struct bits
+{
+  char a;
+  int b:7;
+  int c:9;
+  unsigned char d;
+} x;
+
+struct bits *p;
+
+static void allocit()
+{
+  p = (struct bits *) malloc (sizeof (struct bits));
+}
+
+/* Store into <c> should not clobber <d>.  */
+/* We should not use a 32-bit move to store into p->, but a smaller move.  */
+void foo()
+{
+  allocit();
+  p -> c = 55;
+}
+
+/* { dg-final { scan-assembler-not "movl\t\\(" } } */