Subject: [ext] Re: Addition of compiler flag for dynamic_cast optimization
On Mon, Jul 14 2025, Jonathan Wakely via Gcc wrote:
> On Mon, 14 Jul 2025 at 14:57, Thomas de Bock via Gcc wrote:
>>
>> Hello all, I've been looking into a compiler optimization implemented by
>&
4
To: Thomas de Bock
Cc: gcc@gcc.gnu.org
Subject: [ext] Re: Addition of compiler flag for dynamic_cast optimization
On Mon, 14 Jul 2025 at 14:57, Thomas de Bock via Gcc wrote:
>
> Hello all, I've been looking into a compiler optimization implemented by
> clang but not gcc that substi
Hello all, I've been looking into a compiler optimization implemented by clang
but not gcc that substitutes a __dynamic_cast call for a simple vtable ptr
comparison in the case that the class being cast to is final.
However this brings issues with it in some cases (specified in thread). I
belie
Managed to get it working with:
tree index = build_int_cst (NULL_TREE,
-2 * TARGET_VTABLE_DATA_ENTRY_DISTANCE);
tree src_vptr = build_address(build_vtbl_ref(src_obj, index));
tree trgt_vtbl_decl = get_vtable_decl(target_type, 0);
tree trgt_vtbl_addr =
Currently working with the C++-frontend, I am trying to compare the addresses
of the "trgt" (originally a type) and "src" (originally a class instance)
vtables.
Currently I am successfully retrieving the vptr value of the src instance at
runtime, and the vtable address of the trgt at compiletim
mean I now know I cannot compare the type info in this way, but are there any
already implemented functions that let you retrieve the vtable and the address
of the base class vtable from a type that someone could point me to?
From: Thomas de Bock
Sent: 04 July 20
Bock via Gcc
Sent: 06 July 2025 16:46:16
To: gcc@gcc.gnu.org
Subject: [ext] building generic tree to compare base classes at runtime
Hello, currently working on a tiny experimental compiler optimization in the
C++ frontend. Trying to compare the base classes of 2 types at runtime, then if
they
Hello, currently working on a tiny experimental compiler optimization in the
C++ frontend. Trying to compare the base classes of 2 types at runtime, then if
they are equal, statically cast the second operand's type to the first and the
tree should return the now-casted ptr of the second operand,
Hello, I'm looking to contribute to the project, hoping to implement the
compiler optimization specified in:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63164. Would appreciate any
help/tips regarding what files I should look at to start working towards
implementing something like this, cheers
