bjoernager/rust
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use ptradd for vtable indexing

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Like field offsets, these are always constant.
This commit is contained in:
Erik Desjardins 2024-03-10 22:38:53 -04:00
parent 76ee6fc926
commit a7cd803d02
4 changed files with 104 additions and 17 deletions
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19
compiler/rustc_codegen_ssa/src/meth.rs
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@ -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