On 4/15/25 6:31 AM, Alfie Richards wrote:
This change refactors FMV handling in the frontend to allows greater
reasoning about versions in shared code.
Looking at the cp/ changes:
diff --git a/gcc/cp/class.cc b/gcc/cp/class.cc
index c28d9e5b3ab..4f195ae06cd 100644
--- a/gcc/cp/class.cc
+++ b/gcc/cp/class.cc
@@ -37,6 +37,7 @@ along with GCC; see the file COPYING3. If not see
#include "gimplify.h"
#include "intl.h"
#include "asan.h"
+#include "attribs.h"
This seems unneeded since distinct_ is declared in tree.h.
/* Id for dumping the class hierarchy. */
int class_dump_id;
@@ -8999,8 +9000,7 @@ resolve_address_of_overloaded_function (tree target_type,
decls_match will return false as they are different. */
for (match = TREE_CHAIN (matches); match; match = TREE_CHAIN (match))
if (!decls_match (fn, TREE_PURPOSE (match))
- && !targetm.target_option.function_versions
- (fn, TREE_PURPOSE (match)))
+ && !distinct_version_decls (fn, TREE_PURPOSE (match)))
break;
if (match)
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 898054c2891..ccd9547c2c8 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7121,7 +7121,7 @@ extern void note_iteration_stmt_body_end (bool);
extern void determine_local_discriminator (tree, tree = NULL_TREE);
extern bool member_like_constrained_friend_p (tree);
extern bool fns_correspond (tree, tree);
-extern int decls_match (tree, tree, bool = true);
+extern int decls_match (tree, tree, bool = true,
string_slice* = NULL);
I'm a bit uncomfortable with adding yet another parameter to decls_match
for versioning. Do we really need to pass back the version for
incorporating in the diagnostics? Isn't it enough to print the two
declarations? If not, you could call a function to give more
information about the version mismatch without needing to store it in
duplicate_decls.
extern bool maybe_version_functions (tree, tree);
extern bool validate_constexpr_redeclaration (tree, tree);
extern bool merge_default_template_args (tree, tree, bool);
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index ec4b1755741..4a374fa29e3 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -1120,7 +1120,10 @@ fns_correspond (tree newdecl, tree olddecl)
`const int&'. */
int
-decls_match (tree newdecl, tree olddecl, bool record_versions /* = true */)
+decls_match (tree newdecl,
+ tree olddecl,
+ bool record_versions /* = true */,
+ string_slice *conflicting_version)
{
int types_match;
@@ -1213,7 +1216,7 @@ decls_match (tree newdecl, tree olddecl, bool record_versions /* = true */)
if (types_match
&& !DECL_EXTERN_C_P (newdecl)
&& !DECL_EXTERN_C_P (olddecl)
- && targetm.target_option.function_versions (newdecl, olddecl))
+ && distinct_version_decls (newdecl, olddecl, conflicting_version))
{
if (record_versions)
maybe_version_functions (newdecl, olddecl);
@@ -1296,7 +1299,7 @@ maybe_mark_function_versioned (tree decl)
bool
maybe_version_functions (tree newdecl, tree olddecl)
{
- if (!targetm.target_option.function_versions (newdecl, olddecl))
+ if (!distinct_version_decls (newdecl, olddecl))
return false;
maybe_mark_function_versioned (olddecl);
@@ -1686,11 +1689,12 @@ duplicate_decls (tree newdecl, tree olddecl, bool
hiding, bool was_hidden)
tree new_template_info;
location_t olddecl_loc = DECL_SOURCE_LOCATION (olddecl);
location_t newdecl_loc = DECL_SOURCE_LOCATION (newdecl);
+ string_slice conflicting_version = string_slice::invalid ();
if (newdecl == olddecl)
return olddecl;
- types_match = decls_match (newdecl, olddecl);
+ types_match = decls_match (newdecl, olddecl, true, &conflicting_version);
/* If either the type of the new decl or the type of the old decl is an
error_mark_node, then that implies that we have already issued an
@@ -2106,6 +2110,16 @@ duplicate_decls (tree newdecl, tree olddecl, bool
hiding, bool was_hidden)
/* Leave it to update_binding to merge or report error. */
return NULL_TREE;
}
+ else if (!TARGET_HAS_FMV_TARGET_ATTRIBUTE
+ && !mergeable_version_decls (newdecl, olddecl))
+ {
+ /* newdecl defines an overlapping FMV version with olddecl but they
+ cannot be merged so are conflicting. */
+ gcc_assert (conflicting_version.is_valid ());
+ error_at (newdecl_loc, "conflicting %qB versions", &conflicting_version);
+ inform (olddecl_loc, "previous definition");
That is, here you could call an explain_nonmergeable_versions function.
+ return error_mark_node;
+ }
else
{
const char *errmsg = redeclaration_error_message (newdecl, olddecl);
@@ -2114,10 +2128,23 @@ duplicate_decls (tree newdecl, tree olddecl, bool
hiding, bool was_hidden)
auto_diagnostic_group d;
error_at (newdecl_loc, errmsg, newdecl);
if (DECL_NAME (olddecl) != NULL_TREE)
- inform (olddecl_loc,
- (DECL_INITIAL (olddecl) && namespace_bindings_p ())
- ? G_("%q#D previously defined here")
- : G_("%q#D previously declared here"), olddecl);
+ {
+ /* If conflicting_version is set then this collision is between
+ two FMV annotated functions. */
+ if (conflicting_version.is_valid ())
+ inform (olddecl_loc,
+ (DECL_INITIAL (olddecl) && namespace_bindings_p ())
+ ? G_("%qB version of %q#D previously defined here")
+ : G_("%qB version of %q#D previously declared here"),
...and this seems redundant. Isn't the version printed by %D? If not,
that would be good to do.
+ &conflicting_version,
+ olddecl);
+ else
+ inform (olddecl_loc,
+ (DECL_INITIAL (olddecl) && namespace_bindings_p ())
+ ? G_("%q#D previously defined here")
+ : G_("%q#D previously declared here"),
+ olddecl);
+ }
if (cxx_dialect >= cxx26
&& DECL_NAME (newdecl)
&& id_equal (DECL_NAME (newdecl), "_")
