bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Rollup merge of #122320 - erikdesjardins:vtable, r=nikic

Browse source 
Use ptradd for vtable indexing

Extension of #121665.

After this, the only remaining usages of GEP are [this](cd81f5b27e/compiler/rustc_codegen_llvm/src/intrinsic.rs (L909-L920)) kinda janky Emscription EH code, which I'll change in a future PR, and array indexing / pointer offsets, where there isn't yet a canonical `ptradd` form. (Out of curiosity I tried converting the latter to `ptradd(ptr, mul(size, index))`, but that causes codegen regressions right now.)

r? `@nikic`
This commit is contained in:
Jubilee 2024-03-11 09:29:38 -07:00 • committed by GitHub
commit 028e2600c9
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
4 changed files with 104 additions and 17 deletions
Download patch file Download diff file Expand all files Collapse all files

13
compiler/rustc_codegen_ssa/src/base.rs
View file

@ -165,14 +165,11 @@ pub fn unsized_info<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
cx.tcx().vtable_trait_upcasting_coercion_new_vptr_slot((source, target));
if let Some(entry_idx) = vptr_entry_idx {
let ptr_ty = cx.type_ptr();
let ptr_align = cx.tcx().data_layout.pointer_align.abi;
let gep = bx.inbounds_gep(
ptr_ty,
old_info,
&[bx.const_usize(u64::try_from(entry_idx).unwrap())],
);
let new_vptr = bx.load(ptr_ty, gep, ptr_align);
let ptr_size = bx.data_layout().pointer_size;
let ptr_align = bx.data_layout().pointer_align.abi;
let vtable_byte_offset = u64::try_from(entry_idx).unwrap() * ptr_size.bytes();
let gep = bx.inbounds_ptradd(old_info, bx.const_usize(vtable_byte_offset));
let new_vptr = bx.load(bx.type_ptr(), gep, ptr_align);
bx.nonnull_metadata(new_vptr);
// VTable loads are invariant.
bx.set_invariant_load(new_vptr);

19
compiler/rustc_codegen_ssa/src/meth.rs
View file

@ -20,9 +20,13 @@ impl<'a, 'tcx> VirtualIndex {
ty: Ty<'tcx>,
fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
) -> Bx::Value {
// Load the data pointer from the object.
// Load the function pointer from the object.
debug!("get_fn({llvtable:?}, {ty:?}, {self:?})");
let llty = bx.fn_ptr_backend_type(fn_abi);
let ptr_size = bx.data_layout().pointer_size;
let ptr_align = bx.data_layout().pointer_align.abi;
let vtable_byte_offset = self.0 * ptr_size.bytes();
if bx.cx().sess().opts.unstable_opts.virtual_function_elimination
&& bx.cx().sess().lto() == Lto::Fat
@ -30,12 +34,10 @@ impl<'a, 'tcx> VirtualIndex {
let typeid = bx
.typeid_metadata(typeid_for_trait_ref(bx.tcx(), expect_dyn_trait_in_self(ty)))
.unwrap();
let vtable_byte_offset = self.0 * bx.data_layout().pointer_size.bytes();
let func = bx.type_checked_load(llvtable, vtable_byte_offset, typeid);
func
} else {
let ptr_align = bx.tcx().data_layout.pointer_align.abi;
let gep = bx.inbounds_gep(llty, llvtable, &[bx.const_usize(self.0)]);
let gep = bx.inbounds_ptradd(llvtable, bx.const_usize(vtable_byte_offset));
let ptr = bx.load(llty, gep, ptr_align);
bx.nonnull_metadata(ptr);
// VTable loads are invariant.
@ -53,9 +55,12 @@ impl<'a, 'tcx> VirtualIndex {
debug!("get_int({:?}, {:?})", llvtable, self);
let llty = bx.type_isize();
let usize_align = bx.tcx().data_layout.pointer_align.abi;
let gep = bx.inbounds_gep(llty, llvtable, &[bx.const_usize(self.0)]);
let ptr = bx.load(llty, gep, usize_align);
let ptr_size = bx.data_layout().pointer_size;
let ptr_align = bx.data_layout().pointer_align.abi;
let vtable_byte_offset = self.0 * ptr_size.bytes();
let gep = bx.inbounds_ptradd(llvtable, bx.const_usize(vtable_byte_offset));
let ptr = bx.load(llty, gep, ptr_align);
// VTable loads are invariant.
bx.set_invariant_load(ptr);
ptr