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optimized trans_to_datum::auto_borrow_obj code generation in case some trivial cases where simple copying can be applied

This commit is contained in:
U-NOV2010\eugals 2013-09-17 13:33:36 +04:00 committed by Evgeny Sologubov
parent 99ec14dbb0
commit 2927ab13df
1 changed files with 31 additions and 9 deletions
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40
src/librustc/middle/trans/expr.rs
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@ -313,6 +313,37 @@ pub fn trans_to_datum(bcx: @mut Block, expr: @ast::Expr) -> DatumBlock {
let target_obj_ty = expr_ty_adjusted(bcx, expr);
debug!("auto_borrow_obj(target=%s)",
target_obj_ty.repr(tcx));
// Extract source store information
let (source_store, source_mutbl) = match ty::get(source_datum.ty).sty {
ty::ty_trait(_, _, s, m, _) => (s, m),
_ => {
bcx.sess().span_bug(
expr.span,
fmt!("auto_borrow_trait_obj expected a trait, found %s",
source_datum.ty.repr(bcx.tcx())));
}
};
// check if any borrowing is really needed or we could reuse the source_datum instead
match ty::get(target_obj_ty).sty {
ty::ty_trait(_, _, ty::RegionTraitStore(target_scope), target_mutbl, _) => {
if target_mutbl == ast::MutImmutable && target_mutbl == source_mutbl {
match source_store {
ty::RegionTraitStore(source_scope) => {
if tcx.region_maps.is_subregion_of(target_scope, source_scope) {
return DatumBlock { bcx: bcx, datum: source_datum };
}
},
_ => {}
};
}
},
_ => {}
}
let scratch = scratch_datum(bcx, target_obj_ty,
"__auto_borrow_obj", false);
@ -331,15 +362,6 @@ pub fn trans_to_datum(bcx: @mut Block, expr: @ast::Expr) -> DatumBlock {
// ~T, or &T, depending on source_obj_ty.
let source_data_ptr = GEPi(bcx, source_llval, [0u, abi::trt_field_box]);
let source_data = Load(bcx, source_data_ptr); // always a ptr
let (source_store, source_mutbl) = match ty::get(source_datum.ty).sty {
ty::ty_trait(_, _, s, m, _) => (s, m),
_ => {
bcx.sess().span_bug(
expr.span,
fmt!("auto_borrow_trait_obj expected a trait, found %s",
source_datum.ty.repr(bcx.tcx())));
}
};
let target_data = match source_store {
ty::BoxTraitStore(*) => {
// For deref of @T or @mut T, create a dummy datum and