On 6/12/25 10:53 AM, Alfie Richards wrote:
This patch is an overhaul of how FMV name mangling works. Previously
mangling logic was duplicated in several places across both target
specific and independent code. This patch changes this such that all
mangling is done in targetm.mangle_decl_assembler_name (including for the
dispatched symbol and dispatcher resolver).
Adds the assembler_name member to cgraph_function_version_info to store
the base assembler name of the function set, before FMV mangling.
This allows for the removing of previous hacks, such as where the default
mangled decl's assembler name was unmangled to then remangle all versions
and the resolver and dispatched symbol.
This introduces a change (shown in test changes) for the assembler name of the
dispatched symbol for a x86 versioned function set. Previously it used the
function name mangled twice. This was hard to reproduce without hacks I
wasn't comfortable with. Therefore, the mangling is changed to instead append
".ifunc" which matches clang's behavior.
This change also refactors expand_target_clone using
targetm.mangle_decl_assembler_name for mangling and get_clone_versions.
It is modified such that if the target_clone is in a FMV structure
the ordering is preserved once expanded. This is used later for ACLE semantics
and target_clone/target_version mixing.
gcc/ChangeLog:
* attribs.cc (make_dispatcher_decl): Move duplicated cgraph logic into
this function and change to use targetm.mangle_decl_assembler_name for
mangling.
* cgraph.cc (delete_function_version): Made public static member of
cgraph_node.
(cgraph_node::insert_new_function_version): Record assembler_name.
* cgraph.h (delete_function_version): Ditto.
(struct cgraph_function_version_info): Add assembler_name.
* config/aarch64/aarch64.cc (aarch64_parse_fmv_features): Change to
support string_slice.
(aarch64_process_target_version_attr): Ditto.
(get_feature_mask_for_version): Ditto.
(aarch64_mangle_decl_assembler_name): Add logic for mangling dispatched
symbol and resolver.
(get_suffixed_assembler_name): Removed.
(make_resolver_func): Refactor to use
aarch64_mangle_decl_assembler_name for mangling.
(aarch64_generate_version_dispatcher_body): Remove remangling.
(aarch64_get_function_versions_dispatcher): Refactor to remove
duplicated cgraph logic.
* config/i386/i386-features.cc (is_valid_asm_symbol): Moved from
multiple_target.cc.
(create_new_asm_name): Ditto.
(ix86_mangle_function_version_assembler_name): Refactor to use
clone_identifier and to mangle default.
(ix86_mangle_decl_assembler_name): Add logic for mangling dispatched
symbol and resolver.
(ix86_get_function_versions_dispatcher): Remove duplicated cgraph
logic.
(make_resolver_func): Refactor to use ix86_mangle_decl_assembler_name
for mangling.
* config/riscv/riscv.cc (riscv_mangle_decl_assembler_name): Add logic
for FMV mangling.
(get_suffixed_assembler_name): Removed.
(make_resolver_func): Refactor to use riscv_mangle_decl_assembler_name
for mangling.
(riscv_generate_version_dispatcher_body): Remove unnecessary remangling.
(riscv_get_function_versions_dispatcher): Remove duplicated cgraph
logic.
* config/rs6000/rs6000.cc (rs6000_mangle_decl_assembler_name): New
function.
(rs6000_get_function_versions_dispatcher): Remove duplicated cgraph
logic.
(make_resolver_func): Refactor to use rs6000_mangle_decl_assembler_name
for mangling.
(is_valid_asm_symbol): Move from multiple_target.cc.
(create_new_asm_name): Ditto.
(rs6000_mangle_function_version_assembler_name): New function.
* multiple_target.cc (create_dispatcher_calls): Remove mangling code.
(get_attr_str): Removed.
(separate_attrs): Ditto.
(is_valid_asm_symbol): Moved to target specific.
(create_new_asm_name): Ditto.
(expand_target_clones): Refactor to use
targetm.mangle_decl_assembler_name for mangling and be more general.
* tree.cc (get_target_clone_attr_len): Removed.
* tree.h (get_target_clone_attr_len): Removed.
gcc/cp/ChangeLog:
* decl.cc (maybe_mark_function_versioned): Change to insert function
version
and therefore record assembler name.
gcc/testsuite/ChangeLog:
* g++.target/i386/mv-symbols1.C: Update x86 FMV mangling.
* g++.target/i386/mv-symbols3.C: Ditto.
* g++.target/i386/mv-symbols4.C: Ditto.
* g++.target/i386/mv-symbols5.C: Ditto.
Add assembler_name to cgraph_function_version_info.
Sorry things stalled out a bit. Hopefully we can get through these
larger patches and get this moving again.
So it's unclear why is_valid_asm_symbol and create_new_asm_name moved
out of multiple-target.cc and into the target files themselves. The set
of characters allowed by the former seems like the minimial set that a
target must support to handle C/C++ code. Just not sure why that code
got unfactored.
For create_new_asm_name it looks like it still does the same thing in
all 3 copies, so again, unclear why it got unfactored. Maybe I missed a
subtle change here.
I don't see any obvious dependencies on later patches, so if this patch
can go in now rather than waiting, then it probably should. That gives
it soak time in the event I can't get through the rest of the kit
relatively quickly.
jeff
