On 29/05/15 20:40, Jason Merrill wrote:
On 05/29/2015 09:18 AM, Ramana Radhakrishnan wrote:
+static tree
+build_atomic_load_byte (tree src, HOST_WIDE_INT model)
This function needs a comment. The C++ changes are OK with that.
Jason
I'm assuming your review and rth's review constitute an OK.
Given no regressions on aarch64-none-linux-gnu, arm-none-linux-gnueabihf
and powerpc, I've applied the attached patch.
Ramana
2015-06-04 Ramana Radhakrishnan <ramana.radhakrish...@arm.com>
PR c++/66192
PR target/66200
* doc/tm.texi: Regenerate.
* doc/tm.texi.in (TARGET_RELAXED_ORDERING): Delete.
* target.def (TARGET_RELAXED_ORDERING): Likewise.
* config/alpha/alpha.c (TARGET_RELAXED_ORDERING): Likewise.
* config/ia64/ia64.c (TARGET_RELAXED_ORDERING): Likewise.
* config/rs6000/rs6000.c (TARGET_RELAXED_ORDERING): Likewise.
* config/sparc/linux.h (SPARC_RELAXED_ORDERING): Likewise.
* config/sparc/linux64.h (SPARC_RELAXED_ORDERING): Likewise.
* config/sparc/sparc.c (TARGET_RELAXED_ORDERING): Likewise.
* config/sparc/sparc.h (SPARC_RELAXED_ORDERING): Likewise.
* system.h (TARGET_RELAXED_ORDERING): Poison.
2015-06-04 Ramana Radhakrishnan <ramana.radhakrish...@arm.com>
PR c++/66192
PR target/66200
* cp-tree.h (get_guard_cond): Adjust declaration
* decl.c (expand_static_init): Use atomic load acquire
and adjust call to get_guard_cond.
* decl2.c (build_atomic_load_byte): New function.
(get_guard_cond): Handle thread_safety.
(one_static_initialization_or_destruction): Adjust call to
get_guard_cond.
Index: gcc/ChangeLog
===================================================================
--- gcc/ChangeLog (revision 224117)
+++ gcc/ChangeLog (working copy)
@@ -1,3 +1,18 @@
+2015-06-04 Ramana Radhakrishnan <ramana.radhakrish...@arm.com>
+
+ PR c++/66192
+ PR target/66200
+ * doc/tm.texi: Regenerate.
+ * doc/tm.texi.in (TARGET_RELAXED_ORDERING): Delete.
+ * target.def (TARGET_RELAXED_ORDERING): Likewise.
+ * config/alpha/alpha.c (TARGET_RELAXED_ORDERING): Likewise.
+ * config/ia64/ia64.c (TARGET_RELAXED_ORDERING): Likewise.
+ * config/rs6000/rs6000.c (TARGET_RELAXED_ORDERING): Likewise.
+ * config/sparc/linux.h (SPARC_RELAXED_ORDERING): Likewise.
+ * config/sparc/linux64.h (SPARC_RELAXED_ORDERING): Likewise.
+ * config/sparc/sparc.c (TARGET_RELAXED_ORDERING): Likewise.
+ * config/sparc/sparc.h (SPARC_RELAXED_ORDERING): Likewise.
+
2015-06-04 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
* config/aarch64/aarch64.c (aarch64_override_options): Unconditionally
Index: gcc/config/alpha/alpha.c
===================================================================
--- gcc/config/alpha/alpha.c (revision 224117)
+++ gcc/config/alpha/alpha.c (working copy)
@@ -9987,12 +9987,6 @@
#undef TARGET_EXPAND_BUILTIN_VA_START
#define TARGET_EXPAND_BUILTIN_VA_START alpha_va_start
-/* The Alpha architecture does not require sequential consistency. See
- http://www.cs.umd.edu/~pugh/java/memoryModel/AlphaReordering.html
- for an example of how it can be violated in practice. */
-#undef TARGET_RELAXED_ORDERING
-#define TARGET_RELAXED_ORDERING true
-
#undef TARGET_OPTION_OVERRIDE
#define TARGET_OPTION_OVERRIDE alpha_option_override
Index: gcc/config/ia64/ia64.c
===================================================================
--- gcc/config/ia64/ia64.c (revision 224117)
+++ gcc/config/ia64/ia64.c (working copy)
@@ -630,11 +630,6 @@
#define TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P \
ia64_libgcc_floating_mode_supported_p
-/* ia64 architecture manual 4.4.7: ... reads, writes, and flushes may occur
- in an order different from the specified program order. */
-#undef TARGET_RELAXED_ORDERING
-#define TARGET_RELAXED_ORDERING true
-
#undef TARGET_LEGITIMATE_CONSTANT_P
#define TARGET_LEGITIMATE_CONSTANT_P ia64_legitimate_constant_p
#undef TARGET_LEGITIMATE_ADDRESS_P
Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c (revision 224117)
+++ gcc/config/rs6000/rs6000.c (working copy)
@@ -1620,17 +1620,6 @@
#define TARGET_STACK_PROTECT_FAIL rs6000_stack_protect_fail
#endif
-/* MPC604EUM 3.5.2 Weak Consistency between Multiple Processors
- The PowerPC architecture requires only weak consistency among
- processors--that is, memory accesses between processors need not be
- sequentially consistent and memory accesses among processors can occur
- in any order. The ability to order memory accesses weakly provides
- opportunities for more efficient use of the system bus. Unless a
- dependency exists, the 604e allows read operations to precede store
- operations. */
-#undef TARGET_RELAXED_ORDERING
-#define TARGET_RELAXED_ORDERING true
-
#ifdef HAVE_AS_TLS
#undef TARGET_ASM_OUTPUT_DWARF_DTPREL
#define TARGET_ASM_OUTPUT_DWARF_DTPREL rs6000_output_dwarf_dtprel
Index: gcc/config/sparc/linux.h
===================================================================
--- gcc/config/sparc/linux.h (revision 224117)
+++ gcc/config/sparc/linux.h (working copy)
@@ -139,12 +139,6 @@
/* Static stack checking is supported by means of probes. */
#define STACK_CHECK_STATIC_BUILTIN 1
-/* Linux currently uses RMO in uniprocessor mode, which is equivalent to
- TMO, and TMO in multiprocessor mode. But they reserve the right to
- change their minds. */
-#undef SPARC_RELAXED_ORDERING
-#define SPARC_RELAXED_ORDERING true
-
#undef NEED_INDICATE_EXEC_STACK
#define NEED_INDICATE_EXEC_STACK 1
Index: gcc/config/sparc/linux64.h
===================================================================
--- gcc/config/sparc/linux64.h (revision 224117)
+++ gcc/config/sparc/linux64.h (working copy)
@@ -253,12 +253,6 @@
/* Static stack checking is supported by means of probes. */
#define STACK_CHECK_STATIC_BUILTIN 1
-/* Linux currently uses RMO in uniprocessor mode, which is equivalent to
- TMO, and TMO in multiprocessor mode. But they reserve the right to
- change their minds. */
-#undef SPARC_RELAXED_ORDERING
-#define SPARC_RELAXED_ORDERING true
-
#undef NEED_INDICATE_EXEC_STACK
#define NEED_INDICATE_EXEC_STACK 1
Index: gcc/config/sparc/sparc.c
===================================================================
--- gcc/config/sparc/sparc.c (revision 224117)
+++ gcc/config/sparc/sparc.c (working copy)
@@ -808,9 +808,6 @@
#define TARGET_ATTRIBUTE_TABLE sparc_attribute_table
#endif
-#undef TARGET_RELAXED_ORDERING
-#define TARGET_RELAXED_ORDERING SPARC_RELAXED_ORDERING
-
#undef TARGET_OPTION_OVERRIDE
#define TARGET_OPTION_OVERRIDE sparc_option_override
Index: gcc/config/sparc/sparc.h
===================================================================
--- gcc/config/sparc/sparc.h (revision 224117)
+++ gcc/config/sparc/sparc.h (working copy)
@@ -106,17 +106,6 @@
#define SPARC_DEFAULT_CMODEL CM_32
-/* The SPARC-V9 architecture defines a relaxed memory ordering model (RMO)
- which requires the following macro to be true if enabled. Prior to V9,
- there are no instructions to even talk about memory synchronization.
- Note that the UltraSPARC III processors don't implement RMO, unlike the
- UltraSPARC II processors. Niagara, Niagara-2, and Niagara-3 do not
- implement RMO either.
-
- Default to false; for example, Solaris never enables RMO, only ever uses
- total memory ordering (TMO). */
-#define SPARC_RELAXED_ORDERING false
-
/* Do not use the .note.GNU-stack convention by default. */
#define NEED_INDICATE_EXEC_STACK 0
Index: gcc/cp/ChangeLog
===================================================================
--- gcc/cp/ChangeLog (revision 224117)
+++ gcc/cp/ChangeLog (working copy)
@@ -1,3 +1,15 @@
+2015-06-04 Ramana Radhakrishnan <ramana.radhakrish...@arm.com>
+
+ PR c++/66192
+ PR target/66200
+ * cp-tree.h (get_guard_cond): Adjust declaration
+ * decl.c (expand_static_init): Use atomic load acquire
+ and adjust call to get_guard_cond.
+ * decl2.c (build_atomic_load_byte): New function.
+ (get_guard_cond): Handle thread_safety.
+ (one_static_initialization_or_destruction): Adjust call to
+ get_guard_cond.
+
2015-06-03 Jason Merrill <ja...@redhat.com>
PR c++/44282
Index: gcc/cp/cp-tree.h
===================================================================
--- gcc/cp/cp-tree.h (revision 224117)
+++ gcc/cp/cp-tree.h (working copy)
@@ -5491,7 +5491,7 @@
extern void finish_static_data_member_decl (tree, tree, bool, tree, int);
extern tree cp_build_parm_decl (tree, tree);
extern tree get_guard (tree);
-extern tree get_guard_cond (tree);
+extern tree get_guard_cond (tree, bool);
extern tree set_guard (tree);
extern tree get_tls_wrapper_fn (tree);
extern void mark_needed (tree);
Index: gcc/cp/decl.c
===================================================================
--- gcc/cp/decl.c (revision 224117)
+++ gcc/cp/decl.c (working copy)
@@ -7227,7 +7227,7 @@
looks like:
static <type> guard;
- if (!guard.first_byte) {
+ if (!__atomic_load (guard.first_byte)) {
if (__cxa_guard_acquire (&guard)) {
bool flag = false;
try {
@@ -7257,17 +7257,12 @@
/* Create the guard variable. */
guard = get_guard (decl);
- /* This optimization isn't safe on targets with relaxed memory
- consistency. On such targets we force synchronization in
- __cxa_guard_acquire. */
- if (!targetm.relaxed_ordering || !thread_guard)
- {
- /* Begin the conditional initialization. */
- if_stmt = begin_if_stmt ();
- finish_if_stmt_cond (get_guard_cond (guard), if_stmt);
- then_clause = begin_compound_stmt (BCS_NO_SCOPE);
- }
+ /* Begin the conditional initialization. */
+ if_stmt = begin_if_stmt ();
+ finish_if_stmt_cond (get_guard_cond (guard, thread_guard), if_stmt);
+ then_clause = begin_compound_stmt (BCS_NO_SCOPE);
+
if (thread_guard)
{
tree vfntype = NULL_TREE;
@@ -7335,12 +7330,9 @@
finish_if_stmt (inner_if_stmt);
}
- if (!targetm.relaxed_ordering || !thread_guard)
- {
- finish_compound_stmt (then_clause);
- finish_then_clause (if_stmt);
- finish_if_stmt (if_stmt);
- }
+ finish_compound_stmt (then_clause);
+ finish_then_clause (if_stmt);
+ finish_if_stmt (if_stmt);
}
else if (DECL_THREAD_LOCAL_P (decl))
tls_aggregates = tree_cons (init, decl, tls_aggregates);
Index: gcc/cp/decl2.c
===================================================================
--- gcc/cp/decl2.c (revision 224117)
+++ gcc/cp/decl2.c (working copy)
@@ -3034,6 +3034,27 @@
return guard;
}
+/* Return an atomic load of src with the appropriate memory model. */
+
+static tree
+build_atomic_load_byte (tree src, HOST_WIDE_INT model)
+{
+ tree ptr_type = build_pointer_type (char_type_node);
+ tree mem_model = build_int_cst (integer_type_node, model);
+ tree t, addr, val;
+ unsigned int size;
+ int fncode;
+
+ size = tree_to_uhwi (TYPE_SIZE_UNIT (char_type_node));
+
+ fncode = BUILT_IN_ATOMIC_LOAD_N + exact_log2 (size) + 1;
+ t = builtin_decl_implicit ((enum built_in_function) fncode);
+
+ addr = build1 (ADDR_EXPR, ptr_type, src);
+ val = build_call_expr (t, 2, addr, mem_model);
+ return val;
+}
+
/* Return those bits of the GUARD variable that should be set when the
guarded entity is actually initialized. */
@@ -3060,12 +3081,14 @@
variable has already been initialized. */
tree
-get_guard_cond (tree guard)
+get_guard_cond (tree guard, bool thread_safe)
{
tree guard_value;
- /* Check to see if the GUARD is zero. */
- guard = get_guard_bits (guard);
+ if (!thread_safe)
+ guard = get_guard_bits (guard);
+ else
+ guard = build_atomic_load_byte (guard, MEMMODEL_ACQUIRE);
/* Mask off all but the low bit. */
if (targetm.cxx.guard_mask_bit ())
@@ -3681,7 +3704,7 @@
/* When using __cxa_atexit, we never try to destroy
anything from a static destructor. */
gcc_assert (initp);
- guard_cond = get_guard_cond (guard);
+ guard_cond = get_guard_cond (guard, false);
}
/* If we don't have __cxa_atexit, then we will be running
destructors from .fini sections, or their equivalents. So,
Index: gcc/doc/tm.texi
===================================================================
--- gcc/doc/tm.texi (revision 224117)
+++ gcc/doc/tm.texi (working copy)
@@ -11395,16 +11395,6 @@
and scanf formatter settings.
@end defmac
-@deftypevr {Target Hook} bool TARGET_RELAXED_ORDERING
-If set to @code{true}, means that the target's memory model does not
-guarantee that loads which do not depend on one another will access
-main memory in the order of the instruction stream; if ordering is
-important, an explicit memory barrier must be used. This is true of
-many recent processors which implement a policy of ``relaxed,''
-``weak,'' or ``release'' memory consistency, such as Alpha, PowerPC,
-and ia64. The default is @code{false}.
-@end deftypevr
-
@deftypefn {Target Hook} {const char *} TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN
(const_tree @var{typelist}, const_tree @var{funcdecl}, const_tree @var{val})
If defined, this macro returns the diagnostic message when it is
illegal to pass argument @var{val} to function @var{funcdecl}
Index: gcc/doc/tm.texi.in
===================================================================
--- gcc/doc/tm.texi.in (revision 224117)
+++ gcc/doc/tm.texi.in (working copy)
@@ -8143,8 +8143,6 @@
and scanf formatter settings.
@end defmac
-@hook TARGET_RELAXED_ORDERING
-
@hook TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN
@hook TARGET_INVALID_CONVERSION
Index: gcc/system.h
===================================================================
--- gcc/system.h (revision 224117)
+++ gcc/system.h (working copy)
@@ -964,7 +964,7 @@
TARGET_HANDLE_PRAGMA_EXTERN_PREFIX \
TARGET_VECTORIZE_BUILTIN_MUL_WIDEN_EVEN \
TARGET_VECTORIZE_BUILTIN_MUL_WIDEN_ODD \
- TARGET_MD_ASM_CLOBBERS
+ TARGET_MD_ASM_CLOBBERS TARGET_RELAXED_ORDERING
/* Arrays that were deleted in favor of a functional interface. */
#pragma GCC poison built_in_decls implicit_built_in_decls
Index: gcc/target.def
===================================================================
--- gcc/target.def (revision 224117)
+++ gcc/target.def (working copy)
@@ -5785,19 +5785,6 @@
this to be done. The default is false.",
bool, false)
-/* True if the target is allowed to reorder memory accesses unless
- synchronization is explicitly requested. */
-DEFHOOKPOD
-(relaxed_ordering,
- "If set to @code{true}, means that the target's memory model does not\n\
-guarantee that loads which do not depend on one another will access\n\
-main memory in the order of the instruction stream; if ordering is\n\
-important, an explicit memory barrier must be used. This is true of\n\
-many recent processors which implement a policy of ``relaxed,''\n\
-``weak,'' or ``release'' memory consistency, such as Alpha, PowerPC,\n\
-and ia64. The default is @code{false}.",
- bool, false)
-
/* Returns true if we should generate exception tables for use with the
ARM EABI. The effects the encoding of function exception specifications.
*/
DEFHOOKPOD
