Hi!
As discussed on IRC, decl_binds_to_current_def_p doesn't handle
some cases properly, e.g. if a DECL_COMMON decl has hidden visibility,
then it returns true even without consulting linker plugin resolution,
even when the common might bind to a real definition of the var in some
other TU of the same module.
Fixed by adding new target hook for this. Bootstrapped/regtested on
x86_64-linux and i686-linux, ok for trunk?
2013-06-11 Jakub Jelinek <ja...@redhat.com>
PR target/56564
* output.h (default_binds_to_current_def_p,
default_binds_to_current_def_p_1): New prototypes.
* varasm.c (default_binds_to_current_def_p,
default_binds_to_current_def_p_1): New functions.
(decl_binds_to_current_def): Use binds_to_current_def_p
target hook.
* target.def (binds_to_current_def_p): New hook.
* doc/tm.texi.in (TARGET_BINDS_TO_CURRENT_DEF_P): Document.
* doc/tm.texi: Regenerated.
* config/i386/winnt.c (i386_pe_binds_to_current_def_p): New function.
* config/i386/i386-protos.h (i386_pe_binds_to_current_def_p): New
prototype.
* config/i386/i386.c (TARGET_BINDS_TO_CURRENT_DEF_P): Redefine for
PE and darwin.
* config/darwin-protos.h (darwin_binds_to_current_def_p): New
prototype.
* config/darwin.c (darwin_binds_to_current_def_p): New function.
* config/rs6000/rs6000.c (TARGET_BINDS_TO_CURRENT_DEF_P): Redefine for
darwin.
--- gcc/output.h.jj 2013-01-11 09:03:01.000000000 +0100
+++ gcc/output.h 2013-06-11 08:40:22.247597454 +0200
@@ -583,6 +583,8 @@ extern void default_asm_output_anchor (r
extern bool default_use_anchors_for_symbol_p (const_rtx);
extern bool default_binds_local_p (const_tree);
extern bool default_binds_local_p_1 (const_tree, int);
+extern bool default_binds_to_current_def_p (const_tree);
+extern bool default_binds_to_current_def_p_1 (const_tree, int);
extern void default_globalize_label (FILE *, const char *);
extern void default_globalize_decl_name (FILE *, tree);
extern void default_emit_unwind_label (FILE *, tree, int, int);
--- gcc/varasm.c.jj1 2013-06-11 09:33:52.367820102 +0200
+++ gcc/varasm.c 2013-06-11 11:17:53.162448015 +0200
@@ -6766,46 +6766,80 @@ default_binds_local_p_1 (const_tree exp,
return local_p;
}
-/* Return true when references to DECL must bind to current definition in
- final executable.
+/* Assume ELF-ish defaults, since that's pretty much the most liberal
+ wrt cross-module name binding. */
- The condition is usually equivalent to whether the function binds to the
- current module (shared library or executable), that is to binds_local_p.
- We use this fact to avoid need for another target hook and implement
- the logic using binds_local_p and just special cases where
- decl_binds_to_current_def_p is stronger than binds_local_p. In particular
- the weak definitions (that can be overwritten at linktime by other
- definition from different object file) and when resolution info is available
- we simply use the knowledge passed to us by linker plugin. */
bool
-decl_binds_to_current_def_p (tree decl)
+default_binds_to_current_def_p (const_tree exp)
{
- gcc_assert (DECL_P (decl));
- if (!TREE_PUBLIC (decl))
+ return default_binds_to_current_def_p_1 (exp, flag_shlib);
+}
+
+bool
+default_binds_to_current_def_p_1 (const_tree exp, int shlib)
+{
+ /* Weakrefs may not bind to the current def, even though the weakref itself
is
+ always static and therefore local. Similarly, the resolver for ifunc
functions
+ might resolve to a non-local function.
+ FIXME: We can resolve the weakref case more curefuly by looking at the
+ weakref alias. */
+ if (lookup_attribute ("weakref", DECL_ATTRIBUTES (exp))
+ || (TREE_CODE (exp) == FUNCTION_DECL
+ && lookup_attribute ("ifunc", DECL_ATTRIBUTES (exp))))
+ return false;
+ /* Static variables are always local. */
+ if (! TREE_PUBLIC (exp))
return true;
- if (!targetm.binds_local_p (decl))
+ /* If PIC, then assume that any global name can be overridden by
+ symbols resolved from other modules, unless it has non-default
+ visibility. */
+ if (shlib && DECL_VISIBILITY (exp) == VISIBILITY_DEFAULT)
return false;
- /* When resolution is available, just use it. */
- if (TREE_CODE (decl) == VAR_DECL
- && (TREE_STATIC (decl) || DECL_EXTERNAL (decl)))
+ /* With resolution file in hands, take look into resolutions. */
+ if (TREE_CODE (exp) == VAR_DECL && TREE_PUBLIC (exp)
+ && (TREE_STATIC (exp) || DECL_EXTERNAL (exp)))
{
- struct varpool_node *vnode = varpool_get_node (decl);
+ struct varpool_node *vnode = varpool_get_node (exp);
if (vnode
- && vnode->symbol.resolution != LDPR_UNKNOWN)
- return resolution_to_local_definition_p (vnode->symbol.resolution);
+ && resolution_to_local_definition_p (vnode->symbol.resolution))
+ return true;
}
- else if (TREE_CODE (decl) == FUNCTION_DECL)
+ else if (TREE_CODE (exp) == FUNCTION_DECL && TREE_PUBLIC (exp))
{
- struct cgraph_node *node = cgraph_get_node (decl);
+ struct cgraph_node *node = cgraph_get_node (exp);
if (node
- && node->symbol.resolution != LDPR_UNKNOWN)
- return resolution_to_local_definition_p (node->symbol.resolution);
+ && resolution_to_local_definition_p (node->symbol.resolution))
+ return true;
}
- /* Otherwise we have to assume the worst for DECL_WEAK (hidden weaks
- binds locally but still can be overwritten).
- This rely on fact that binds_local_p behave as decl_replaceable_p
- for all other declaration types. */
- return !DECL_WEAK (decl);
+ /* Variables defined outside this object might not be local. */
+ if (DECL_EXTERNAL (exp))
+ return false;
+ /* Weak data can be overridden by a strong symbol in another TU
+ and so might not bind to current def. */
+ if (DECL_WEAK (exp))
+ return false;
+ /* Uninitialized COMMON variable may be unified with symbols
+ resolved from other TUs. */
+ if (DECL_COMMON (exp)
+ && (DECL_INITIAL (exp) == NULL
+ || DECL_INITIAL (exp) == error_mark_node))
+ return false;
+ /* Otherwise we're left with initialized (or non-common) global data
+ which is of necessity bound to the current def. */
+ return true;
+}
+
+/* Return true when references to DECL must bind to current definition in
+ final executable.
+
+ The condition is often equivalent to whether the function binds to the
+ current module (shared library or executable), that is to binds_local_p. */
+
+bool
+decl_binds_to_current_def_p (tree decl)
+{
+ gcc_assert (DECL_P (decl));
+ return targetm.binds_to_current_def_p (decl);
}
/* A replaceable function or variable is one which may be replaced
--- gcc/target.def.jj 2013-06-01 14:47:19.000000000 +0200
+++ gcc/target.def 2013-06-11 08:41:33.901416274 +0200
@@ -1569,6 +1569,14 @@ DEFHOOK
bool, (const_tree exp),
default_binds_local_p)
+/* True if EXP names an object for which name resolution must resolve
+ to the definition in the current translation unit. */
+DEFHOOK
+(binds_to_current_def_p,
+ "",
+ bool, (const_tree exp),
+ default_binds_to_current_def_p)
+
/* Check if profiling code is before or after prologue. */
DEFHOOK
(profile_before_prologue,
--- gcc/doc/tm.texi.in.jj 2013-06-10 18:16:38.000000000 +0200
+++ gcc/doc/tm.texi.in 2013-06-11 08:49:39.208401706 +0200
@@ -7082,6 +7082,15 @@ for ELF, which has a looser model of glo
currently supported object file formats.
@end deftypefn
+@hook TARGET_BINDS_TO_CURRENT_DEF_P
+Returns true if @var{exp} names an object for which name resolution
+rules must resolve to the definition in the current translation unit.
+
+The default version of this hook implements the name resolution rules
+for ELF, which has a looser model of global name binding than other
+currently supported object file formats.
+@end deftypefn
+
@hook TARGET_HAVE_TLS
Contains the value true if the target supports thread-local storage.
The default value is false.
--- gcc/doc/tm.texi.jj 2013-06-10 18:16:38.000000000 +0200
+++ gcc/doc/tm.texi 2013-06-11 08:50:16.933780317 +0200
@@ -7200,6 +7200,15 @@ for ELF, which has a looser model of glo
currently supported object file formats.
@end deftypefn
+@deftypefn {Target Hook} bool TARGET_BINDS_TO_CURRENT_DEF_P (const_tree
@var{exp})
+Returns true if @var{exp} names an object for which name resolution
+rules must resolve to the definition in the current translation unit.
+
+The default version of this hook implements the name resolution rules
+for ELF, which has a looser model of global name binding than other
+currently supported object file formats.
+@end deftypefn
+
@deftypevr {Target Hook} bool TARGET_HAVE_TLS
Contains the value true if the target supports thread-local storage.
The default value is false.
--- gcc/config/i386/winnt.c.jj 2013-06-01 14:47:25.000000000 +0200
+++ gcc/config/i386/winnt.c 2013-06-11 08:47:30.710520722 +0200
@@ -368,6 +368,16 @@ i386_pe_binds_local_p (const_tree exp)
return default_binds_local_p_1 (exp, 0);
}
+bool
+i386_pe_binds_to_current_def_p (const_tree exp)
+{
+ if ((TREE_CODE (exp) == VAR_DECL || TREE_CODE (exp) == FUNCTION_DECL)
+ && DECL_DLLIMPORT_P (exp))
+ return false;
+
+ return default_binds_to_current_def_p_1 (exp, 0);
+}
+
/* Also strip the fastcall prefix and stdcall suffix. */
const char *
--- gcc/config/i386/i386-protos.h.jj 2013-06-10 18:16:38.000000000 +0200
+++ gcc/config/i386/i386-protos.h 2013-06-11 08:47:54.823121655 +0200
@@ -246,6 +246,7 @@ extern void i386_pe_record_external_func
extern void i386_pe_maybe_record_exported_symbol (tree, const char *, int);
extern void i386_pe_encode_section_info (tree, rtx, int);
extern bool i386_pe_binds_local_p (const_tree);
+extern bool i386_pe_binds_to_current_def_p (const_tree);
extern const char *i386_pe_strip_name_encoding_full (const char *);
extern bool i386_pe_valid_dllimport_attribute_p (const_tree);
extern unsigned int i386_pe_section_type_flags (tree, const char *, int);
--- gcc/config/i386/i386.c.jj 2013-06-10 18:16:38.000000000 +0200
+++ gcc/config/i386/i386.c 2013-06-11 08:46:21.326665064 +0200
@@ -42814,10 +42814,14 @@ ix86_memmodel_check (unsigned HOST_WIDE_
#if TARGET_MACHO
#undef TARGET_BINDS_LOCAL_P
#define TARGET_BINDS_LOCAL_P darwin_binds_local_p
+#undef TARGET_BINDS_TO_CURRENT_DEF_P
+#define TARGET_BINDS_TO_CURRENT_DEF_P darwin_binds_to_current_def_p
#endif
#if TARGET_DLLIMPORT_DECL_ATTRIBUTES
#undef TARGET_BINDS_LOCAL_P
#define TARGET_BINDS_LOCAL_P i386_pe_binds_local_p
+#undef TARGET_BINDS_TO_CURRENT_DEF_P
+#define TARGET_BINDS_TO_CURRENT_DEF_P i386_pe_binds_to_current_def_p
#endif
#undef TARGET_ASM_OUTPUT_MI_THUNK
--- gcc/config/darwin-protos.h.jj 2013-01-11 09:03:07.000000000 +0100
+++ gcc/config/darwin-protos.h 2013-06-11 08:45:23.621620232 +0200
@@ -108,6 +108,7 @@ extern void darwin_asm_output_aligned_de
unsigned int);
extern bool darwin_binds_local_p (const_tree);
+extern bool darwin_binds_to_current_def_p (const_tree);
extern void darwin_cpp_builtins (struct cpp_reader *);
extern tree darwin_init_cfstring_builtins (unsigned);
--- gcc/config/darwin.c.jj 2013-02-12 11:23:35.000000000 +0100
+++ gcc/config/darwin.c 2013-06-11 08:44:42.406298454 +0200
@@ -2933,6 +2933,17 @@ darwin_binds_local_p (const_tree decl)
TARGET_KEXTABI && DARWIN_VTABLE_P (decl));
}
+/* Name binding to current TU. Darwin does not support overriding
+ functions at dynamic-link time, except for vtables in kexts. */
+
+bool
+darwin_binds_to_current_def_p (const_tree decl)
+{
+ return default_binds_to_current_def_p_1 (decl,
+ TARGET_KEXTABI
+ && DARWIN_VTABLE_P (decl));
+}
+
/* The Darwin's implementation of TARGET_ASM_OUTPUT_ANCHOR. Define the
anchor relative to ".", the current section position. We cannot use
the default one because ASM_OUTPUT_DEF is wrong for Darwin. */
--- gcc/config/rs6000/rs6000.c.jj 2013-06-11 08:01:26.000000000 +0200
+++ gcc/config/rs6000/rs6000.c 2013-06-11 09:10:31.585540013 +0200
@@ -1335,6 +1335,8 @@ static const struct attribute_spec rs600
#if TARGET_MACHO
#undef TARGET_BINDS_LOCAL_P
#define TARGET_BINDS_LOCAL_P darwin_binds_local_p
+#undef TARGET_BINDS_TO_CURRENT_DEF_P
+#define TARGET_BINDS_TO_CURRENT_DEF_P darwin_binds_to_current_def_p
#endif
#undef TARGET_MS_BITFIELD_LAYOUT_P
Jakub
