rust/tests/codegen/vtable-loads.rs, branch 1.88.0https://github.com/rust-lang/rust
http://git.dreamy.place/mirrors/rust/atom?h=1.88.02025-02-11T21:41:35+00:00tests/codegen: use -Copt-level=3 instead of -O2025-02-11T21:41:35+00:00Jubilee Youngworkingjubilee@gmail.com2025-02-09T03:45:40+00:00urn:sha1:3c0c9b6770f1ac0324be91580f52b6f45346e47bOmit non-needs_drop drop_in_place in vtables2024-05-27T20:26:56+00:00Mark Rousskovmark.simulacrum@gmail.com2024-03-17T21:42:37+00:00urn:sha1:4c002fce9d8421096538273c9b78db7d68529b94
This replaces the drop_in_place reference with null in vtables. On
librustc_driver.so, this drops about ~17k dynamic relocations from the
output, since many vtables can now be placed in read-only memory, rather
than having a relocated pointer included.
This makes a tradeoff by adding a null check at vtable call sites.
That's hard to avoid without changing the vtable format (e.g., to use a
pc-relative relocation instead of an absolute address, and avoid the
dynamic relocation that way). But it seems likely that the check is
cheap at runtime.