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Update other codegens to use tcx managed vtable allocations.

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This commit is contained in:
Charles Lew
2021-06-20 17:43:25 +08:00
parent 654e3345e5
commit d3ff497bec
12 changed files with 144 additions and 250 deletions
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108
compiler/rustc_codegen_cranelift/src/vtable.rs
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@@ -4,7 +4,7 @@
// FIXME dedup this logic between miri, cg_llvm and cg_clif
use crate::prelude::*;
use ty::VtblEntry;
use super::constant::pointer_for_allocation;
fn vtable_memflags() -> MemFlags {
let mut flags = MemFlags::trusted(); // A vtable access is always aligned and will never trap.
@@ -66,105 +66,19 @@ pub(crate) fn get_ptr_and_method_ref<'tcx>(
pub(crate) fn get_vtable<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
layout: TyAndLayout<'tcx>,
ty: Ty<'tcx>,
trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
) -> Value {
let data_id = if let Some(data_id) = fx.vtables.get(&(layout.ty, trait_ref)) {
*data_id
let vtable_ptr = if let Some(vtable_ptr) = fx.vtables.get(&(ty, trait_ref)) {
*vtable_ptr
} else {
let data_id = build_vtable(fx, layout, trait_ref);
fx.vtables.insert((layout.ty, trait_ref), data_id);
data_id
let vtable_alloc_id = fx.tcx.vtable_allocation(ty, trait_ref);
let vtable_allocation = fx.tcx.global_alloc(vtable_alloc_id).unwrap_memory();
let vtable_ptr = pointer_for_allocation(fx, vtable_allocation);
fx.vtables.insert((ty, trait_ref), vtable_ptr);
vtable_ptr
};
let local_data_id = fx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
fx.bcx.ins().global_value(fx.pointer_type, local_data_id)
}
fn build_vtable<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
layout: TyAndLayout<'tcx>,
trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
) -> DataId {
let tcx = fx.tcx;
let usize_size = fx.layout_of(fx.tcx.types.usize).size.bytes() as usize;
let drop_in_place_fn = import_function(
tcx,
fx.module,
Instance::resolve_drop_in_place(tcx, layout.ty).polymorphize(fx.tcx),
);
let vtable_entries = if let Some(trait_ref) = trait_ref {
tcx.vtable_entries(trait_ref.with_self_ty(tcx, layout.ty))
} else {
ty::COMMON_VTABLE_ENTRIES
};
let mut data_ctx = DataContext::new();
let mut data = ::std::iter::repeat(0u8)
.take(vtable_entries.len() * usize_size)
.collect::<Vec<u8>>()
.into_boxed_slice();
for (idx, entry) in vtable_entries.iter().enumerate() {
match entry {
VtblEntry::MetadataSize => {
write_usize(fx.tcx, &mut data, idx, layout.size.bytes());
}
VtblEntry::MetadataAlign => {
write_usize(fx.tcx, &mut data, idx, layout.align.abi.bytes());
}
VtblEntry::MetadataDropInPlace | VtblEntry::Vacant | VtblEntry::Method(_, _) => {}
}
}
data_ctx.define(data);
for (idx, entry) in vtable_entries.iter().enumerate() {
match entry {
VtblEntry::MetadataDropInPlace => {
let func_ref = fx.module.declare_func_in_data(drop_in_place_fn, &mut data_ctx);
data_ctx.write_function_addr((idx * usize_size) as u32, func_ref);
}
VtblEntry::Method(def_id, substs) => {
let func_id = import_function(
tcx,
fx.module,
Instance::resolve_for_vtable(tcx, ParamEnv::reveal_all(), *def_id, substs)
.unwrap()
.polymorphize(fx.tcx),
);
let func_ref = fx.module.declare_func_in_data(func_id, &mut data_ctx);
data_ctx.write_function_addr((idx * usize_size) as u32, func_ref);
}
VtblEntry::MetadataSize | VtblEntry::MetadataAlign | VtblEntry::Vacant => {}
}
}
data_ctx.set_align(fx.tcx.data_layout.pointer_align.pref.bytes());
let data_id = fx.module.declare_anonymous_data(false, false).unwrap();
fx.module.define_data(data_id, &data_ctx).unwrap();
data_id
}
fn write_usize(tcx: TyCtxt<'_>, buf: &mut [u8], idx: usize, num: u64) {
let pointer_size =
tcx.layout_of(ParamEnv::reveal_all().and(tcx.types.usize)).unwrap().size.bytes() as usize;
let target = &mut buf[idx * pointer_size..(idx + 1) * pointer_size];
match tcx.data_layout.endian {
rustc_target::abi::Endian::Little => match pointer_size {
4 => target.copy_from_slice(&(num as u32).to_le_bytes()),
8 => target.copy_from_slice(&(num as u64).to_le_bytes()),
_ => todo!("pointer size {} is not yet supported", pointer_size),
},
rustc_target::abi::Endian::Big => match pointer_size {
4 => target.copy_from_slice(&(num as u32).to_be_bytes()),
8 => target.copy_from_slice(&(num as u64).to_be_bytes()),
_ => todo!("pointer size {} is not yet supported", pointer_size),
},
}
vtable_ptr.get_addr(fx)
}