> Hi,
> also I just became aware that this patch hits the following bug of gold
> http://sourceware.org/bugzilla/show_bug.cgi?id=14342
> It makes gcc.dg/tree-prof/crossmodule-indircall-1.c fail with the bogus
> diagnostic on TLS and non-TLS use of the same symbol. I attached the
> details into the PR. GNU-LD works.
>
> I am not sure if I can workaround this problem except for convincing users to
> always use -fno-lto with -fprofile-generate. Shall we fix it in mainline
> binutils + document that earlier binutils are broken with -fporfile-generate
> -flto?
Hi,
it seems that the bug also appeared in later GNU-LDs. So I made the following
workaround that with -flto switches back to old API of indirect_call_profiler
and it makes new hidden variables in profiling code. This avoid mixing of
accesses of the TLS variable from LTO and non-LTO code.
Unless someone suggests me a better solution soon, I will go with this hack.
It ought to be essentially harmless just adding some extra overhead to -flto
-fprofile-generate (same as we had before patch). Things will also still break
if you produce fat LTO -fprofile-generate objects and link some with LTO and
others without. I do not think we need to support this with binutils bug.
Honza
Index: libgcc/Makefile.in
===================================================================
--- libgcc/Makefile.in (revision 201539)
+++ libgcc/Makefile.in (working copy)
@@ -857,7 +857,7 @@ LIBGCOV = _gcov _gcov_merge_add _gcov_me
_gcov_execv _gcov_execvp _gcov_execve _gcov_reset _gcov_dump \
_gcov_interval_profiler _gcov_pow2_profiler _gcov_one_value_profiler \
_gcov_indirect_call_profiler _gcov_average_profiler _gcov_ior_profiler \
- _gcov_merge_ior
+ _gcov_merge_ior _gcov_indirect_call_profiler_v2
libgcov-objects = $(patsubst %,%$(objext),$(LIBGCOV))
Index: libgcc/libgcov.c
===================================================================
--- libgcc/libgcov.c (revision 201539)
+++ libgcc/libgcov.c (working copy)
@@ -1120,6 +1120,8 @@ __gcov_one_value_profiler (gcov_type *co
#endif
#ifdef L_gcov_indirect_call_profiler
+/* This function exist only for workaround of binutils bug 14342.
+ Once this compatibility hack is obsolette, it can be removed. */
/* By default, the C++ compiler will use function addresses in the
vtable entries. Setting TARGET_VTABLE_USES_DESCRIPTORS to nonzero
@@ -1141,18 +1143,90 @@ __gcov_one_value_profiler (gcov_type *co
/* Tries to determine the most common value among its inputs. */
void
__gcov_indirect_call_profiler (gcov_type* counter, gcov_type value,
- void* cur_func, void* callee_func)
+ void* cur_func, void* callee_func)
{
/* If the C++ virtual tables contain function descriptors then one
function may have multiple descriptors and we need to dereference
the descriptors to see if they point to the same function. */
if (cur_func == callee_func
|| (VTABLE_USES_DESCRIPTORS && callee_func
- && *(void **) cur_func == *(void **) callee_func))
+ && *(void **) cur_func == *(void **) callee_func))
__gcov_one_value_profiler_body (counter, value);
}
+
+#endif
+#ifdef L_gcov_indirect_call_profiler_v2
+
+/* These two variables are used to actually track caller and callee. Keep
+ them in TLS memory so races are not common (they are written to often).
+ The variables are set directly by GCC instrumented code, so declaration
+ here must match one in tree-profile.c */
+
+#ifdef HAVE_CC_TLS
+__thread
+#endif
+void * __gcov_indirect_call_callee;
+#ifdef HAVE_CC_TLS
+__thread
+#endif
+gcov_type * __gcov_indirect_call_counters;
+
+/* By default, the C++ compiler will use function addresses in the
+ vtable entries. Setting TARGET_VTABLE_USES_DESCRIPTORS to nonzero
+ tells the compiler to use function descriptors instead. The value
+ of this macro says how many words wide the descriptor is (normally 2),
+ but it may be dependent on target flags. Since we do not have access
+ to the target flags here we just check to see if it is set and use
+ that to set VTABLE_USES_DESCRIPTORS to 0 or 1.
+
+ It is assumed that the address of a function descriptor may be treated
+ as a pointer to a function. */
+
+#ifdef TARGET_VTABLE_USES_DESCRIPTORS
+#define VTABLE_USES_DESCRIPTORS 1
+#else
+#define VTABLE_USES_DESCRIPTORS 0
#endif
+/* Tries to determine the most common value among its inputs. */
+void
+__gcov_indirect_call_profiler_v2 (gcov_type value, void* cur_func)
+{
+ /* If the C++ virtual tables contain function descriptors then one
+ function may have multiple descriptors and we need to dereference
+ the descriptors to see if they point to the same function. */
+ if (cur_func == __gcov_indirect_call_callee
+ || (VTABLE_USES_DESCRIPTORS && __gcov_indirect_call_callee
+ && *(void **) cur_func == *(void **) __gcov_indirect_call_callee))
+ __gcov_one_value_profiler_body (__gcov_indirect_call_counters, value);
+}
+#endif
+
+#ifdef L_gcov_time_profiler
+
+static int function_counter = 0;
+
+void
+__gcov_time_profiler (gcov_type* counters)
+{
+ function_counter++;
+
+ /* counters[0] indicates a first visit of the function. */
+ if (counters[0] == 0)
+ {
+ counters[0] = function_counter;
+ fprintf (stderr, "__gcov_time_profiler:%d\n", counters[0]);
+ }
+ fprintf (stderr, "__gcov_time_profiler:%d\n", counters[0]);
+
+ /* counters[1] is last visit of the function. */
+ counters[1] = function_counter;
+
+ /* counters[2] indicated if visited */
+ if (counters[2] == 0)
+ counters[2] = 1;
+}
+#endif
#ifdef L_gcov_average_profiler
/* Increase corresponding COUNTER by VALUE. FIXME: Perhaps we want
Index: gcc/tree-profile.c
===================================================================
--- gcc/tree-profile.c (revision 201640)
+++ gcc/tree-profile.c (working copy)
@@ -67,13 +67,28 @@ init_ic_make_global_vars (void)
ptr_void = build_pointer_type (void_type_node);
- ic_void_ptr_var
- = build_decl (UNKNOWN_LOCATION, VAR_DECL,
- get_identifier ("__gcov_indirect_call_callee"),
- ptr_void);
+ /* Workaround for binutils bug 14342. Once it is fixed, remove lto path. */
+ if (flag_lto)
+ {
+ ic_void_ptr_var
+ = build_decl (UNKNOWN_LOCATION, VAR_DECL,
+ get_identifier ("__gcov_indirect_call_callee_ltopriv"),
+ ptr_void);
+ TREE_PUBLIC (ic_void_ptr_var) = 1;
+ DECL_COMMON (ic_void_ptr_var) = 1;
+ DECL_VISIBILITY (ic_void_ptr_var) = VISIBILITY_HIDDEN;
+ DECL_VISIBILITY_SPECIFIED (ic_void_ptr_var) = true;
+ }
+ else
+ {
+ ic_void_ptr_var
+ = build_decl (UNKNOWN_LOCATION, VAR_DECL,
+ get_identifier ("__gcov_indirect_call_callee"),
+ ptr_void);
+ TREE_PUBLIC (ic_void_ptr_var) = 1;
+ DECL_EXTERNAL (ic_void_ptr_var) = 1;
+ }
TREE_STATIC (ic_void_ptr_var) = 1;
- TREE_PUBLIC (ic_void_ptr_var) = 1;
- DECL_EXTERNAL (ic_void_ptr_var) = 1;
DECL_ARTIFICIAL (ic_void_ptr_var) = 1;
DECL_INITIAL (ic_void_ptr_var) = NULL;
if (targetm.have_tls)
@@ -83,13 +98,28 @@ init_ic_make_global_vars (void)
varpool_finalize_decl (ic_void_ptr_var);
gcov_type_ptr = build_pointer_type (get_gcov_type ());
- ic_gcov_type_ptr_var
- = build_decl (UNKNOWN_LOCATION, VAR_DECL,
- get_identifier ("__gcov_indirect_call_counters"),
- gcov_type_ptr);
+ /* Workaround for binutils bug 14342. Once it is fixed, remove lto path. */
+ if (flag_lto)
+ {
+ ic_gcov_type_ptr_var
+ = build_decl (UNKNOWN_LOCATION, VAR_DECL,
+ get_identifier ("__gcov_indirect_call_counters_ltopriv"),
+ gcov_type_ptr);
+ TREE_PUBLIC (ic_gcov_type_ptr_var) = 1;
+ DECL_COMMON (ic_gcov_type_ptr_var) = 1;
+ DECL_VISIBILITY (ic_gcov_type_ptr_var) = VISIBILITY_HIDDEN;
+ DECL_VISIBILITY_SPECIFIED (ic_gcov_type_ptr_var) = true;
+ }
+ else
+ {
+ ic_gcov_type_ptr_var
+ = build_decl (UNKNOWN_LOCATION, VAR_DECL,
+ get_identifier ("__gcov_indirect_call_counters"),
+ gcov_type_ptr);
+ TREE_PUBLIC (ic_gcov_type_ptr_var) = 1;
+ DECL_EXTERNAL (ic_gcov_type_ptr_var) = 1;
+ }
TREE_STATIC (ic_gcov_type_ptr_var) = 1;
- TREE_PUBLIC (ic_gcov_type_ptr_var) = 1;
- DECL_EXTERNAL (ic_gcov_type_ptr_var) = 1;
DECL_ARTIFICIAL (ic_gcov_type_ptr_var) = 1;
DECL_INITIAL (ic_gcov_type_ptr_var) = NULL;
if (targetm.have_tls)
@@ -157,15 +187,31 @@ gimple_init_edge_profiler (void)
init_ic_make_global_vars ();
- /* void (*) (gcov_type, void *) */
- ic_profiler_fn_type
- = build_function_type_list (void_type_node,
- gcov_type_node,
- ptr_void,
- NULL_TREE);
- tree_indirect_call_profiler_fn
- = build_fn_decl ("__gcov_indirect_call_profiler_v2",
- ic_profiler_fn_type);
+ /* Workaround for binutils bug 14342. Once it is fixed, remove lto
path. */
+ if (flag_lto)
+ {
+ /* void (*) (gcov_type, void *) */
+ ic_profiler_fn_type
+ = build_function_type_list (void_type_node,
+ gcov_type_ptr, gcov_type_node,
+ ptr_void, ptr_void,
+ NULL_TREE);
+ tree_indirect_call_profiler_fn
+ = build_fn_decl ("__gcov_indirect_call_profiler",
+ ic_profiler_fn_type);
+ }
+ else
+ {
+ /* void (*) (gcov_type, void *) */
+ ic_profiler_fn_type
+ = build_function_type_list (void_type_node,
+ gcov_type_node,
+ ptr_void,
+ NULL_TREE);
+ tree_indirect_call_profiler_fn
+ = build_fn_decl ("__gcov_indirect_call_profiler_v2",
+ ic_profiler_fn_type);
+ }
TREE_NOTHROW (tree_indirect_call_profiler_fn) = 1;
DECL_ATTRIBUTES (tree_indirect_call_profiler_fn)
= tree_cons (get_identifier ("leaf"), NULL,
@@ -375,8 +421,25 @@ gimple_gen_ic_func_profiler (void)
true, GSI_SAME_STMT);
tree_uid = build_int_cst
(gcov_type_node, cgraph_get_node
(current_function_decl)->profile_id);
- stmt1 = gimple_build_call (tree_indirect_call_profiler_fn, 2,
- tree_uid, cur_func);
+ /* Workaround for binutils bug 14342. Once it is fixed, remove lto path. */
+ if (flag_lto)
+ {
+ tree counter_ptr, ptr_var;
+ counter_ptr = force_gimple_operand_gsi (&gsi, ic_gcov_type_ptr_var,
+ true, NULL_TREE, true,
+ GSI_SAME_STMT);
+ ptr_var = force_gimple_operand_gsi (&gsi, ic_void_ptr_var,
+ true, NULL_TREE, true,
+ GSI_SAME_STMT);
+
+ stmt1 = gimple_build_call (tree_indirect_call_profiler_fn, 4,
+ counter_ptr, tree_uid, cur_func, ptr_var);
+ }
+ else
+ {
+ stmt1 = gimple_build_call (tree_indirect_call_profiler_fn, 2,
+ tree_uid, cur_func);
+ }
gsi_insert_before (&gsi, stmt1, GSI_SAME_STMT);
/* Set __gcov_indirect_call_callee to 0,
