bjoernager/rust
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Merge pull request #69 from oli-obk/master

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don't force allocations for most casts
This commit is contained in:
Scott Olson 2016-10-21 11:06:19 -06:00 • committed by GitHub
commit c148d887e3
1 changed files with 18 additions and 29 deletions
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47
src/interpreter/mod.rs
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@ -652,9 +652,6 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
}
Cast(kind, ref operand, cast_ty) => {
// FIXME(solson)
let dest = self.force_allocation(dest)?.to_ptr();
debug_assert_eq!(self.monomorphize(cast_ty, self.substs()), dest_ty);
use rustc::mir::repr::CastKind::*;
match kind {
@ -669,34 +666,27 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
let src_ty = self.operand_ty(operand);
if self.type_is_fat_ptr(src_ty) {
trace!("misc cast: {:?}", src);
let ptr_size = self.memory.pointer_size();
match (src, self.type_is_fat_ptr(dest_ty)) {
(Value::ByValPair(data, meta), true) => {
self.memory.write_primval(dest, data)?;
self.memory.write_primval(dest.offset(ptr_size as isize), meta)?;
(Value::ByRef(_), _) |
(Value::ByValPair(..), true) => {
self.write_value(src, dest, dest_ty)?;
},
(Value::ByValPair(data, _), false) => {
self.memory.write_primval(dest, data)?;
},
(Value::ByRef(ptr), true) => {
self.memory.copy(ptr, dest, ptr_size * 2, ptr_size)?;
},
(Value::ByRef(ptr), false) => {
self.memory.copy(ptr, dest, ptr_size, ptr_size)?;
self.write_value(Value::ByVal(data), dest, dest_ty)?;
},
(Value::ByVal(_), _) => bug!("expected fat ptr"),
}
} else {
let src_val = self.value_to_primval(src, src_ty)?;
let dest_val = self.cast_primval(src_val, dest_ty)?;
self.memory.write_primval(dest, dest_val)?;
self.write_value(Value::ByVal(dest_val), dest, dest_ty)?;
}
}
ReifyFnPointer => match self.operand_ty(operand).sty {
ty::TyFnDef(def_id, substs, fn_ty) => {
let fn_ptr = self.memory.create_fn_ptr(def_id, substs, fn_ty);
self.memory.write_ptr(dest, fn_ptr)?;
self.write_value(Value::ByVal(PrimVal::from_fn_ptr(fn_ptr)), dest, dest_ty)?;
},
ref other => bug!("reify fn pointer on {:?}", other),
},
@ -707,7 +697,7 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
let ptr = src.read_ptr(&self.memory)?;
let (def_id, substs, _) = self.memory.get_fn(ptr.alloc_id)?;
let fn_ptr = self.memory.create_fn_ptr(def_id, substs, unsafe_fn_ty);
self.memory.write_ptr(dest, fn_ptr)?;
self.write_value(Value::ByVal(PrimVal::from_fn_ptr(fn_ptr)), dest, dest_ty)?;
},
ref other => bug!("fn to unsafe fn cast on {:?}", other),
},
@ -1492,7 +1482,7 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
&mut self,
src: Value,
src_ty: Ty<'tcx>,
dest: Pointer,
dest: Lvalue<'tcx>,
dest_ty: Ty<'tcx>,
) -> EvalResult<'tcx, ()> {
match (&src_ty.sty, &dest_ty.sty) {
@ -1506,33 +1496,32 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
match (&src_pointee_ty.sty, &dest_pointee_ty.sty) {
(&ty::TyArray(_, length), &ty::TySlice(_)) => {
let ptr = src.read_ptr(&self.memory)?;
self.memory.write_ptr(dest, ptr)?;
let ptr_size = self.memory.pointer_size() as isize;
let dest_extra = dest.offset(ptr_size);
self.memory.write_usize(dest_extra, length as u64)?;
let len = self.usize_primval(length as u64);
let ptr = PrimVal::from_ptr(ptr);
self.write_value(Value::ByValPair(ptr, len), dest, dest_ty)?;
}
(&ty::TyTrait(_), &ty::TyTrait(_)) => {
// For now, upcasts are limited to changes in marker
// traits, and hence never actually require an actual
// change to the vtable.
self.write_value_to_ptr(src, dest, dest_ty)?;
self.write_value(src, dest, dest_ty)?;
},
(_, &ty::TyTrait(ref data)) => {
let trait_ref = data.principal.with_self_ty(self.tcx, src_pointee_ty);
let trait_ref = self.tcx.erase_regions(&trait_ref);
let vtable = self.get_vtable(trait_ref)?;
let ptr = src.read_ptr(&self.memory)?;
self.memory.write_ptr(dest, ptr)?;
let ptr_size = self.memory.pointer_size() as isize;
let dest_extra = dest.offset(ptr_size);
self.memory.write_ptr(dest_extra, vtable)?;
let ptr = PrimVal::from_ptr(ptr);
let extra = PrimVal::from_ptr(vtable);
self.write_value(Value::ByValPair(ptr, extra), dest, dest_ty)?;
},
_ => bug!("invalid unsizing {:?} -> {:?}", src_ty, dest_ty),
}
}
(&ty::TyAdt(def_a, substs_a), &ty::TyAdt(def_b, substs_b)) => {
// FIXME(solson)
let dest = self.force_allocation(dest)?.to_ptr();
// unsizing of generic struct with pointer fields
// Example: `Arc<T>` -> `Arc<Trait>`
// here we need to increase the size of every &T thin ptr field to a fat ptr
@ -1563,7 +1552,7 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
if src_fty == dst_fty {
self.copy(src_f_ptr, dst_f_ptr, src_fty)?;
} else {
self.unsize_into(Value::ByRef(src_f_ptr), src_fty, dst_f_ptr, dst_fty)?;
self.unsize_into(Value::ByRef(src_f_ptr), src_fty, Lvalue::from_ptr(dst_f_ptr), dst_fty)?;
}
}
}