bjoernager/rust
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unify passing of sized and unsized function arguments :-)

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This commit is contained in:
Ralf Jung 2023-08-17 18:59:39 +02:00
parent 7cdeff266c
commit f87e91de7d
2 changed files with 36 additions and 32 deletions
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34
compiler/rustc_const_eval/src/interpret/terminator.rs
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@ -1,5 +1,4 @@
use std::borrow::Cow;
use std::mem;
use either::Either;
use rustc_ast::ast::InlineAsmOptions;
@ -15,8 +14,8 @@ use rustc_target::abi::{self, FieldIdx};
use rustc_target::spec::abi::Abi;
use super::{
AllocId, FnVal, ImmTy, InterpCx, InterpResult, LocalValue, MPlaceTy, Machine, MemoryKind, OpTy,
Operand, PlaceTy, Provenance, Scalar, StackPopCleanup,
AllocId, FnVal, ImmTy, InterpCx, InterpResult, MPlaceTy, Machine, OpTy, PlaceTy, Projectable,
Provenance, Scalar, StackPopCleanup,
};
use crate::fluent_generated as fluent;
@ -394,28 +393,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// did in-place of by-copy argument passing, except for pointer equality tests.
let caller_arg_copy = self.copy_fn_arg(&caller_arg)?;
if !already_live {
// Special handling for unsized parameters: they are harder to make live.
if caller_arg_copy.layout.is_unsized() {
// `check_argument_compat` ensures that both have the same type, so we know they will use the metadata the same way.
assert_eq!(caller_arg_copy.layout.ty, callee_ty);
// We have to properly pre-allocate the memory for the callee.
// So let's tear down some abstractions.
// This all has to be in memory, there are no immediate unsized values.
let src = caller_arg_copy.assert_mem_place();
// The destination cannot be one of these "spread args".
let dest_local = callee_arg.as_local().expect("unsized arguments cannot be spread");
// Allocate enough memory to hold `src`.
let dest_place = self.allocate_dyn(src.layout, MemoryKind::Stack, src.meta)?;
// Update the local to be that new place. This is essentially a "dyn-sized StorageLive".
let old = mem::replace(
&mut self.frame_mut().locals[dest_local].value,
LocalValue::Live(Operand::Indirect(*dest_place)),
);
assert!(matches!(old, LocalValue::Dead));
} else {
// Just make the local live.
self.storage_live(callee_arg.as_local().unwrap())?;
}
let local = callee_arg.as_local().unwrap();
let meta = caller_arg_copy.meta();
// `check_argument_compat` ensures that if metadata is needed, both have the same type,
// so we know they will use the metadata the same way.
assert!(!meta.has_meta() || caller_arg_copy.layout.ty == callee_ty);
self.storage_live_dyn(local, meta)?;
}
// Now we can finally actually evaluate the callee place.
let callee_arg = self.eval_place(*callee_arg)?;