auto merge of #7495 : thestinger/rust/exchange, r=cmr

With these changes, exchange allocator headers are never initialized, read or written to. Removing the header will now just involve updating the code in trans using an offset to only do it if the type contained is managed.

The only thing blocking removing the initialization of the last field in the header was ~fn since it uses it to store the dynamic size/types due to captures. I temporarily switched it to a `closure_exchange_alloc` lang item (it uses the same `exchange_free`) and #7496 is filed about removing that.

Since the `exchange_free` call is now inlined all over the codebase, I don't think we should have an assert for null. It doesn't currently ever happen, but it would be fine if we started generating code that did do it. The `exchange_free` function also had a comment declaring that it must not fail, but a regular assert would cause a failure. I also removed the atomic counter because valgrind can already find these leaks, and we have valgrind bots now.

Note that exchange free does not currently print an error an out-of-memory when it aborts, because our `io` code may allocate. We could probably get away with a `#[rust_stack]` call to a `stdio` function but it would be better to make a write system call.

src/librustc/middle/lang_items.rs

@@ -32,63 +32,64 @@ use syntax::visit::visit_crate;
 use std::hashmap::HashMap;
 
 pub enum LangItem {
-    FreezeTraitLangItem,        // 0
-    CopyTraitLangItem,          // 1
-    SendTraitLangItem,          // 2
-    SizedTraitLangItem,         // 3
-
-    DropTraitLangItem,          // 4
-
-    AddTraitLangItem,           // 5
-    SubTraitLangItem,           // 6
-    MulTraitLangItem,           // 7
-    DivTraitLangItem,           // 8
-    RemTraitLangItem,           // 9
-    NegTraitLangItem,           // 10
-    NotTraitLangItem,           // 11
-    BitXorTraitLangItem,        // 11
-    BitAndTraitLangItem,        // 13
-    BitOrTraitLangItem,         // 14
-    ShlTraitLangItem,           // 15
-    ShrTraitLangItem,           // 16
-    IndexTraitLangItem,         // 17
-
-    EqTraitLangItem,            // 18
-    OrdTraitLangItem,           // 19
-
-    StrEqFnLangItem,            // 20
-    UniqStrEqFnLangItem,        // 21
-    AnnihilateFnLangItem,       // 22
-    LogTypeFnLangItem,          // 23
-    FailFnLangItem,             // 24
-    FailBoundsCheckFnLangItem,  // 25
-    ExchangeMallocFnLangItem,   // 26
-    ExchangeFreeFnLangItem,     // 27
-    MallocFnLangItem,           // 28
-    FreeFnLangItem,             // 29
-    BorrowAsImmFnLangItem,      // 30
-    BorrowAsMutFnLangItem,      // 31
-    ReturnToMutFnLangItem,      // 32
-    CheckNotBorrowedFnLangItem, // 33
-    StrDupUniqFnLangItem,       // 34
-    RecordBorrowFnLangItem,     // 35
-    UnrecordBorrowFnLangItem,   // 36
-
-    StartFnLangItem,            // 37
-
-    TyDescStructLangItem,       // 38
-    TyVisitorTraitLangItem,     // 39
-    OpaqueStructLangItem,       // 40
+    FreezeTraitLangItem,               // 0
+    CopyTraitLangItem,                 // 1
+    SendTraitLangItem,                 // 2
+    SizedTraitLangItem,                // 3
+
+    DropTraitLangItem,                 // 4
+
+    AddTraitLangItem,                  // 5
+    SubTraitLangItem,                  // 6
+    MulTraitLangItem,                  // 7
+    DivTraitLangItem,                  // 8
+    RemTraitLangItem,                  // 9
+    NegTraitLangItem,                  // 10
+    NotTraitLangItem,                  // 11
+    BitXorTraitLangItem,               // 11
+    BitAndTraitLangItem,               // 13
+    BitOrTraitLangItem,                // 14
+    ShlTraitLangItem,                  // 15
+    ShrTraitLangItem,                  // 16
+    IndexTraitLangItem,                // 17
+
+    EqTraitLangItem,                   // 18
+    OrdTraitLangItem,                  // 19
+
+    StrEqFnLangItem,                   // 20
+    UniqStrEqFnLangItem,               // 21
+    AnnihilateFnLangItem,              // 22
+    LogTypeFnLangItem,                 // 23
+    FailFnLangItem,                    // 24
+    FailBoundsCheckFnLangItem,         // 25
+    ExchangeMallocFnLangItem,          // 26
+    ClosureExchangeMallocFnLangItem,   // 27
+    ExchangeFreeFnLangItem,            // 28
+    MallocFnLangItem,                  // 29
+    FreeFnLangItem,                    // 30
+    BorrowAsImmFnLangItem,             // 31
+    BorrowAsMutFnLangItem,             // 32
+    ReturnToMutFnLangItem,             // 33
+    CheckNotBorrowedFnLangItem,        // 34
+    StrDupUniqFnLangItem,              // 35
+    RecordBorrowFnLangItem,            // 36
+    UnrecordBorrowFnLangItem,          // 37
+
+    StartFnLangItem,                   // 38
+
+    TyDescStructLangItem,              // 39
+    TyVisitorTraitLangItem,            // 40
+    OpaqueStructLangItem,              // 41
 }
 
 pub struct LanguageItems {
-    items: [Option<def_id>, ..41]
+    items: [Option<def_id>, ..42]
 }
 
 impl LanguageItems {
     pub fn new() -> LanguageItems {
         LanguageItems {
-            items: [ None, ..41 ]
+            items: [ None, ..42 ]
         }
     }
 
@@ -128,22 +129,23 @@ impl LanguageItems {
             24 => "fail_",
             25 => "fail_bounds_check",
             26 => "exchange_malloc",
-            27 => "exchange_free",
-            28 => "malloc",
-            29 => "free",
-            30 => "borrow_as_imm",
-            31 => "borrow_as_mut",
-            32 => "return_to_mut",
-            33 => "check_not_borrowed",
-            34 => "strdup_uniq",
-            35 => "record_borrow",
-            36 => "unrecord_borrow",
-
-            37 => "start",
-
-            38 => "ty_desc",
-            39 => "ty_visitor",
-            40 => "opaque",
+            27 => "closure_exchange_malloc",
+            28 => "exchange_free",
+            29 => "malloc",
+            30 => "free",
+            31 => "borrow_as_imm",
+            32 => "borrow_as_mut",
+            33 => "return_to_mut",
+            34 => "check_not_borrowed",
+            35 => "strdup_uniq",
+            36 => "record_borrow",
+            37 => "unrecord_borrow",
+
+            38 => "start",
+
+            39 => "ty_desc",
+            40 => "ty_visitor",
+            41 => "opaque",
 
             _ => "???"
         }
@@ -236,6 +238,9 @@ impl LanguageItems {
     pub fn exchange_malloc_fn(&self) -> def_id {
         self.items[ExchangeMallocFnLangItem as uint].get()
     }
+    pub fn closure_exchange_malloc_fn(&self) -> def_id {
+        self.items[ClosureExchangeMallocFnLangItem as uint].get()
+    }
     pub fn exchange_free_fn(&self) -> def_id {
         self.items[ExchangeFreeFnLangItem as uint].get()
     }
@@ -326,6 +331,7 @@ impl<'self> LanguageItemCollector<'self> {
         item_refs.insert(@"fail_bounds_check",
                          FailBoundsCheckFnLangItem as uint);
         item_refs.insert(@"exchange_malloc", ExchangeMallocFnLangItem as uint);
+        item_refs.insert(@"closure_exchange_malloc", ClosureExchangeMallocFnLangItem as uint);
         item_refs.insert(@"exchange_free", ExchangeFreeFnLangItem as uint);
         item_refs.insert(@"malloc", MallocFnLangItem as uint);
         item_refs.insert(@"free", FreeFnLangItem as uint);

src/librustc/middle/trans/base.rs

@@ -253,6 +253,9 @@ pub fn malloc_raw_dyn(bcx: block,
         heap_exchange => {
             (ty::mk_imm_uniq, bcx.tcx().lang_items.exchange_malloc_fn())
         }
+        heap_exchange_closure => {
+            (ty::mk_imm_uniq, bcx.tcx().lang_items.closure_exchange_malloc_fn())
+        }
     };
 
     // Grab the TypeRef type of box_ptr_ty.

src/librustc/middle/trans/closure.rs

@@ -159,6 +159,14 @@ pub fn mk_closure_tys(tcx: ty::ctxt,
     return cdata_ty;
 }
 
+fn heap_for_unique_closure(bcx: block, t: ty::t) -> heap {
+    if ty::type_contents(bcx.tcx(), t).contains_managed() {
+        heap_managed_unique
+    } else {
+        heap_exchange_closure
+    }
+}
+
 pub fn allocate_cbox(bcx: block, sigil: ast::Sigil, cdata_ty: ty::t)
                   -> Result {
     let _icx = push_ctxt("closure::allocate_cbox");
@@ -181,7 +189,7 @@ pub fn allocate_cbox(bcx: block, sigil: ast::Sigil, cdata_ty: ty::t)
             malloc_raw(bcx, cdata_ty, heap_managed)
         }
         ast::OwnedSigil => {
-            malloc_raw(bcx, cdata_ty, heap_for_unique(bcx, cdata_ty))
+            malloc_raw(bcx, cdata_ty, heap_for_unique_closure(bcx, cdata_ty))
         }
         ast::BorrowedSigil => {
             let cbox_ty = tuplify_box_ty(tcx, cdata_ty);
@@ -526,7 +534,7 @@ pub fn make_opaque_cbox_take_glue(
         let rval = alloca(bcx, Type::i8p());
         let bcx = callee::trans_lang_call(
             bcx,
-            bcx.tcx().lang_items.exchange_malloc_fn(),
+            bcx.tcx().lang_items.closure_exchange_malloc_fn(),
             [opaque_tydesc, sz],
             expr::SaveIn(rval));
         let cbox_out = PointerCast(bcx, Load(bcx, rval), llopaquecboxty);

src/librustc/middle/trans/common.rs

@@ -275,6 +275,7 @@ pub enum heap {
     heap_managed,
     heap_managed_unique,
     heap_exchange,
+    heap_exchange_closure
 }
 
 #[deriving(Eq)]
@@ -384,7 +385,7 @@ pub fn add_clean_free(cx: block, ptr: ValueRef, heap: heap) {
         let f: @fn(block) -> block = |a| glue::trans_free(a, ptr);
         f
       }
-      heap_exchange => {
+      heap_exchange | heap_exchange_closure => {
         let f: @fn(block) -> block = |a| glue::trans_exchange_free(a, ptr);
         f
       }

src/librustc/middle/trans/foreign.rs

@@ -750,6 +750,12 @@ pub fn trans_intrinsic(ccx: @mut CrateContext,
                   C_bool(ty::type_needs_drop(ccx.tcx, tp_ty)),
                   fcx.llretptr.get());
         }
+        "contains_managed" => {
+            let tp_ty = substs.tys[0];
+            Store(bcx,
+                  C_bool(ty::type_contents(ccx.tcx, tp_ty).contains_managed()),
+                  fcx.llretptr.get());
+        }
         "visit_tydesc" => {
             let td = get_param(decl, first_real_arg);
             let visitor = get_param(decl, first_real_arg + 1u);

src/librustc/middle/trans/tvec.rs

@@ -321,6 +321,7 @@ pub fn trans_uniq_or_managed_vstore(bcx: block, heap: heap, vstore_expr: @ast::e
                 _ => {}
             }
         }
+        heap_exchange_closure => fail!("vectors are not allocated with closure_exchange_alloc"),
         heap_managed | heap_managed_unique => {}
     }
 

src/librustc/middle/trans/type_use.rs

@@ -127,7 +127,7 @@ pub fn type_uses_for(ccx: @mut CrateContext, fn_id: def_id, n_tps: uint)
                     "uninit"   | "init" | "transmute" | "move_val" |
                     "move_val_init" => use_repr,
 
-                    "get_tydesc" | "needs_drop" => use_tydesc,
+                    "get_tydesc" | "needs_drop" | "contains_managed" => use_tydesc,
 
                     "visit_tydesc"  | "forget" | "frame_address" |
                     "morestack_addr" => 0,

src/librustc/middle/trans/uniq.rs

@@ -52,13 +52,5 @@ pub fn duplicate(bcx: block, src_box: ValueRef, src_ty: ty::t) -> Result {
     } = malloc_unique(bcx, body_datum.ty);
     body_datum.copy_to(bcx, datum::INIT, dst_body);
 
-    // Copy the type descriptor
-    let src_tydesc_ptr = GEPi(bcx, src_box,
-                              [0u, back::abi::box_field_tydesc]);
-    let dst_tydesc_ptr = GEPi(bcx, dst_box,
-                              [0u, back::abi::box_field_tydesc]);
-    let td = Load(bcx, src_tydesc_ptr);
-    Store(bcx, td, dst_tydesc_ptr);
-
-    return rslt(bcx, dst_box);
+    rslt(bcx, dst_box)
 }

src/librustc/middle/typeck/check/mod.rs

@@ -3539,7 +3539,7 @@ pub fn check_intrinsic_type(ccx: @mut CrateCtxt, it: @ast::foreign_item) {
                ty::mk_nil())
             }
             "needs_drop" => (1u, ~[], ty::mk_bool()),
-
+            "contains_managed" => (1u, ~[], ty::mk_bool()),
             "atomic_xchg"     | "atomic_xadd"     | "atomic_xsub"     |
             "atomic_xchg_acq" | "atomic_xadd_acq" | "atomic_xsub_acq" |
             "atomic_xchg_rel" | "atomic_xadd_rel" | "atomic_xsub_rel" => {

src/libstd/managed.rs

@@ -17,7 +17,6 @@ use ptr::to_unsafe_ptr;
 pub mod raw {
     use std::unstable::intrinsics::TyDesc;
 
-    pub static RC_EXCHANGE_UNIQUE : uint = (-1) as uint;
     pub static RC_MANAGED_UNIQUE : uint = (-2) as uint;
     pub static RC_IMMORTAL : uint = 0x77777777;
 

src/libstd/os.rs

@@ -730,7 +730,7 @@ pub fn list_dir(p: &Path) -> ~[~str] {
         #[cfg(windows)]
         unsafe fn get_list(p: &Path) -> ~[~str] {
             use libc::consts::os::extra::INVALID_HANDLE_VALUE;
-            use libc::wcslen;
+            use libc::{wcslen, free};
             use libc::funcs::extra::kernel32::{
                 FindFirstFileW,
                 FindNextFileW,
@@ -739,7 +739,7 @@ pub fn list_dir(p: &Path) -> ~[~str] {
             use os::win32::{
                 as_utf16_p
             };
-            use rt::global_heap::{malloc_raw, free_raw};
+            use rt::global_heap::malloc_raw;
             #[nolink]
             extern {
                 unsafe fn rust_list_dir_wfd_size() -> libc::size_t;
@@ -772,7 +772,7 @@ pub fn list_dir(p: &Path) -> ~[~str] {
                             ::cast::transmute(wfd_ptr));
                     }
                     FindClose(find_handle);
-                    free_raw(wfd_ptr);
+                    free(wfd_ptr)
                 }
                 strings
             }