Revert "rt: Use obstacks in lieu of dynamically-sized frames"

This reverts commit cc5fcfc.

Author: pcwalton

src/comp/middle/trans.rs

@@ -466,20 +466,17 @@ fn alloca(cx: &@block_ctxt, t: TypeRef) -> ValueRef {
 }
 
 fn array_alloca(cx: &@block_ctxt, t: TypeRef, n: ValueRef) -> ValueRef {
-    let bcx = cx;
     let builder = new_builder(cx.fcx.lldynamicallocas);
-    let lltaskptr = bcx_fcx(bcx).lltaskptr;
-
-    let dynastack_alloc = bcx_ccx(bcx).upcalls.dynastack_alloc;
-    let llsz = builder.Mul(C_uint(llsize_of_real(bcx_ccx(bcx), t)), n);
-    let llresult = builder.Call(dynastack_alloc, ~[lltaskptr, llsz]);
-    ret builder.PointerCast(llresult, T_ptr(t));
-}
-
-fn mk_obstack_token(ccx: &@crate_ctxt, lldynamicallocas: BasicBlockRef,
-                    lltaskptr: ValueRef) -> ValueRef {
-    let builder = new_builder(lldynamicallocas);
-    ret builder.Call(ccx.upcalls.dynastack_mark, ~[lltaskptr]);
+    alt bcx_fcx(cx).llobstacktoken {
+        none. {
+            let dynastack_mark = bcx_ccx(cx).upcalls.dynastack_mark;
+            let lltaskptr = bcx_fcx(cx).lltaskptr;
+            bcx_fcx(cx).llobstacktoken =
+                some(builder.Call(dynastack_mark, ~[lltaskptr]));
+        }
+        some(_) { /* no-op */ }
+    }
+    ret builder.ArrayAlloca(t, n);
 }
 
 
@@ -4410,8 +4407,6 @@ fn trans_bind_thunk(cx: &@local_ctxt, sp: &span, incoming_fty: &ty::t,
     lltargetfn = bcx.build.PointerCast(lltargetfn, T_ptr(T_ptr(lltargetty)));
     lltargetfn = bcx.build.Load(lltargetfn);
     llvm::LLVMSetTailCall(bcx.build.FastCall(lltargetfn, llargs), 1);
-
-    bcx = trans_fn_cleanups(bcx);   // TODO: Might break tail call.
     bcx.build.RetVoid();
     finish_fn(fcx, lltop);
     ret {val: llthunk, ty: llthunk_ty};
@@ -5616,8 +5611,14 @@ fn trans_block_cleanups(cx: &@block_ctxt, cleanup_cx: &@block_ctxt) ->
 }
 
 fn trans_fn_cleanups(bcx: &@block_ctxt) -> @block_ctxt {
-    bcx.build.Call(bcx_ccx(bcx).upcalls.dynastack_free,
-                   ~[bcx_fcx(bcx).lltaskptr, bcx_fcx(bcx).llobstacktoken]);
+    alt bcx_fcx(bcx).llobstacktoken {
+        some(lltoken_) {
+            let lltoken = lltoken_; // satisfy alias checker
+            bcx.build.Call(bcx_ccx(bcx).upcalls.dynastack_free,
+                           ~[bcx_fcx(bcx).lltaskptr, lltoken]);
+        }
+        none. { /* nothing to do */ }
+    }
     ret bcx;
 }
 
@@ -5806,7 +5807,6 @@ fn new_fn_ctxt_w_id(cx: @local_ctxt, sp: &span, llfndecl: ValueRef,
     let derived_tydescs =
         map::mk_hashmap::<ty::t, derived_tydesc_info>(ty::hash_ty, ty::eq_ty);
     let llbbs = mk_standard_basic_blocks(llfndecl);
-    let llobstacktoken = mk_obstack_token(cx.ccx, llbbs.da, lltaskptr);
     ret @{llfn: llfndecl,
           lltaskptr: lltaskptr,
           llenv: llenv,
@@ -5816,7 +5816,7 @@ fn new_fn_ctxt_w_id(cx: @local_ctxt, sp: &span, llfndecl: ValueRef,
           mutable llderivedtydescs_first: llbbs.dt,
           mutable llderivedtydescs: llbbs.dt,
           mutable lldynamicallocas: llbbs.da,
-          mutable llobstacktoken: llobstacktoken,
+          mutable llobstacktoken: none::<ValueRef>,
           mutable llself: none::<val_self_pair>,
           mutable lliterbody: none::<ValueRef>,
           mutable iterbodyty: none::<ty::t>,
@@ -6137,7 +6137,6 @@ fn trans_res_ctor(cx: @local_ctxt, sp: &span, dtor: &ast::_fn,
     let flag = GEP_tup_like(bcx, tup_t, llretptr, ~[0, 0]);
     bcx = flag.bcx;
     bcx.build.Store(C_int(1), flag.val);
-    bcx = trans_fn_cleanups(bcx);
     bcx.build.RetVoid();
     finish_fn(fcx, lltop);
 }
@@ -6434,7 +6433,6 @@ fn create_main_wrapper(ccx: &@crate_ctxt, sp: &span,
             };
             bcx.build.FastCall(main_llfn, args);
         }
-        bcx = trans_fn_cleanups(bcx);
         bcx.build.RetVoid();
 
         let lltop = bcx.llbb;
@@ -6756,7 +6754,6 @@ fn decl_native_fn_and_pair(ccx: &@crate_ctxt, sp: &span, path: &[str],
     for d: {val: ValueRef, ty: ty::t} in drop_args {
         bcx = drop_ty(bcx, d.val, d.ty).bcx;
     }
-    bcx = trans_fn_cleanups(bcx);
     bcx.build.RetVoid();
     finish_fn(fcx, lltop);
 }

src/comp/middle/trans_common.rs

@@ -215,7 +215,8 @@ type fn_ctxt = {
     mutable lldynamicallocas: BasicBlockRef,
 
     // The token used to clear the dynamic allocas at the end of this frame.
-    mutable llobstacktoken: ValueRef,
+    // Will be |none| if there are no dynamic allocas.
+    mutable llobstacktoken: option::t<ValueRef>,
 
     // The 'self' object currently in use in this function, if there
     // is one.

src/comp/middle/trans_objects.rs

@@ -192,8 +192,6 @@ fn trans_obj(cx: @local_ctxt, sp: &span, ob: &ast::_obj,
         let p = bcx.build.PointerCast(box.box, llbox_ty);
         bcx.build.Store(p, pair_box);
     }
-
-    bcx = trans_fn_cleanups(bcx);
     bcx.build.RetVoid();
 
     // Insert the mandatory first few basic blocks before lltop.
@@ -712,7 +710,6 @@ fn process_bkwding_mthd(cx: @local_ctxt, sp: &span, m: @ty::method,
     // And, finally, call the outer method.
     bcx.build.FastCall(llouter_mthd, llouter_mthd_args);
 
-    bcx = trans_fn_cleanups(bcx);
     bcx.build.RetVoid();
     finish_fn(fcx, lltop);
 
@@ -885,7 +882,6 @@ fn process_fwding_mthd(cx: @local_ctxt, sp: &span, m: @ty::method,
     // And, finally, call the original (inner) method.
     bcx.build.FastCall(llorig_mthd, llorig_mthd_args);
 
-    bcx = trans_fn_cleanups(bcx);
     bcx.build.RetVoid();
     finish_fn(fcx, lltop);
 

src/rt/rust_obstack.cpp

@@ -14,12 +14,7 @@
 #undef max
 #endif
 
-//#define DPRINT(fmt,...)     fprintf(stderr, fmt, ##__VA_ARGS__)
-#define DPRINT(fmt,...)
-
-//const size_t DEFAULT_CHUNK_SIZE = 4096;
-const size_t DEFAULT_CHUNK_SIZE = 300000;
-const size_t DEFAULT_ALIGNMENT = 16;
+const size_t DEFAULT_CHUNK_SIZE = 4096;
 
 struct rust_obstack_chunk {
     rust_obstack_chunk *prev;
@@ -37,13 +32,8 @@ struct rust_obstack_chunk {
 
 void *
 rust_obstack_chunk::alloc(size_t len) {
-    alen = align_to(alen, DEFAULT_ALIGNMENT);
-
-    if (len > size - alen) {
-        DPRINT("Not enough space, len=%lu!\n", len);
-        assert(0);
+    if (len > size - alen)
         return NULL;    // Not enough space.
-    }
     void *result = data + alen;
     alen += len;
     return result;
@@ -52,7 +42,7 @@ rust_obstack_chunk::alloc(size_t len) {
 bool
 rust_obstack_chunk::free(void *ptr) {
     uint8_t *p = (uint8_t *)ptr;
-    if (p < data || p > data + size)
+    if (p < data || p >= data + size)
         return false;
     assert(p <= data + alen);
     alen = (size_t)(p - data);
@@ -64,7 +54,6 @@ void *
 rust_obstack::alloc_new(size_t len) {
     size_t chunk_size = std::max(len, DEFAULT_CHUNK_SIZE);
     void *ptr = task->malloc(sizeof(chunk) + chunk_size, "obstack");
-    DPRINT("making new chunk at %p, len %lu\n", ptr, chunk_size);
     chunk = new(ptr) rust_obstack_chunk(chunk, chunk_size);
     return chunk->alloc(len);
 }
@@ -81,12 +70,8 @@ void *
 rust_obstack::alloc(size_t len) {
     if (!chunk)
         return alloc_new(len);
-
-    DPRINT("alloc sz %u", (uint32_t)len);
-
     void *ptr = chunk->alloc(len);
     ptr = ptr ? ptr : alloc_new(len);
-
     return ptr;
 }
 
@@ -95,11 +80,8 @@ rust_obstack::free(void *ptr) {
     if (!ptr)
         return;
 
-    DPRINT("free ptr %p\n", ptr);
-
     assert(chunk);
     while (!chunk->free(ptr)) {
-        DPRINT("deleting chunk at %p\n", chunk);
         rust_obstack_chunk *prev = chunk->prev;
         task->free(chunk);
         chunk = prev;

src/rt/rust_shape.cpp

@@ -64,6 +64,18 @@ const uint8_t CMP_LT = 1u;
 const uint8_t CMP_LE = 2u;
 
 
+// Utility functions
+
+// Rounds |size| to the nearest |alignment|. Invariant: |alignment| is a power
+// of two.
+template<typename T>
+static inline T
+align_to(T size, size_t alignment) {
+    assert(alignment);
+    T x = (T)(((uintptr_t)size + alignment - 1) & ~(alignment - 1));
+    return x;
+}
+
 // Utility classes
 
 struct size_align {
@@ -173,18 +185,11 @@ class ptr_pair {
     }
 };
 
-}   // end namespace shape
-
-
-inline shape::ptr_pair
-align_to(const shape::ptr_pair &pair, size_t n) {
-    return shape::ptr_pair::make(align_to(pair.fst, n),
-                                 align_to(pair.snd, n));
+inline ptr_pair
+align_to(const ptr_pair &pair, size_t n) {
+    return ptr_pair::make(align_to(pair.fst, n), align_to(pair.snd, n));
 }
 
-
-namespace shape {
-
 // NB: This function does not align.
 template<typename T>
 inline data_pair<T>

src/rt/rust_upcall.cpp

@@ -430,7 +430,7 @@ upcall_dynastack_mark(rust_task *task) {
 /** Allocates space in the dynamic stack and returns it. */
 extern "C" CDECL void *
 upcall_dynastack_alloc(rust_task *task, size_t sz) {
-    return sz ? task->dynastack.alloc(sz) : NULL;
+    return task->dynastack.alloc(sz);
 }
 
 /** Frees space in the dynamic stack. */

src/rt/rust_util.h

@@ -125,16 +125,6 @@ next_power_of_two(size_t s)
     return tmp + 1;
 }
 
-// Rounds |size| to the nearest |alignment|. Invariant: |alignment| is a power
-// of two.
-template<typename T>
-static inline T
-align_to(T size, size_t alignment) {
-    assert(alignment);
-    T x = (T)(((uintptr_t)size + alignment - 1) & ~(alignment - 1));
-    return x;
-}
-
 // Initialization helper for ISAAC RNG
 
 template <typename sched_or_kernel>