@chapter Specials
@menu
-* Overview::
-* Binding and unbinding::
+* Overview::
+* Binding and unbinding::
@end menu
@node Overview
@section Binding and unbinding
Binding goes like this: the binding stack pointer (bsp) is bumped, old
-value and symbol are stored at bsp - 1, new value is stored in
-symbol's value slot or the tls.
+value and symbol are stored at bsp - 1, new value is stored in symbol's
+value slot or the tls. On multithreaded builds, @code{TLS-INDEX} is
+stored on the binding stack in place of the symbol.
Unbinding: the symbol's value is restored from bsp - 1, value and
symbol at bsp - 1 are set to zero, and finally bsp is decremented.
In other words, the invariant is that the binding stack above bsp only
contains zeros. This makes @code{BIND} safe in face of gc triggered at
any point during its execution.
+
+On platforms with the @code{UNWIND-TO-FRAME-AND-CALL-VOP} feature, it's
+possible to restart frames in the debugger, unwinding the binding stack.
+To know how much to unwind, @code{BIND-SENTINEL} in the beginning of a
+function puts the current frame pointer on the binding stack with
+@code{UNBOUND-MARKER-WIDETAG} instead of the symbol/tls-index.
+@code{UNBIND-SENTINEL} removes it before returning. The debugger then
+search for @code{UNBOUND-MARKER-WIDETAG} with the value being equal to
+the desired frame, and calls @code{UNBIND-TO-HERE}. Consequently,
+@code{UNBIND-TO-HERE} treats @code{UNBOUND-MARKER-WIDETAG} the same way
+as zeros.
+
;;; Establish VAL as a binding for SYMBOL. Save the old value and the
;;; symbol on the binding stack and stuff the new value into the symbol.
+;;;
+;;; See the "Chapter 9: Specials" of the SBCL Internals Manual.
+
(define-vop (bind)
(:args (val :scs (any-reg descriptor-reg))
(symbol :scs (descriptor-reg)))
(define-primitive-object (binding)
value
- symbol)
+ symbol) ;; on sb-thread, this is actually a tls-index
(define-primitive-object (unwind-block)
(current-uwp :c-type #!-alpha "struct unwind_block *" #!+alpha "u32")
(package :ref-trans symbol-package
:set-trans %set-symbol-package
:init :null)
- #!+sb-thread (tls-index :ref-known (flushable) :ref-trans symbol-tls-index))
+ ;; 0 tls-index means no tls-index is allocated
+ #!+sb-thread
+ (tls-index :ref-known (flushable) :ref-trans symbol-tls-index))
(define-primitive-object (complex-single-float
:lowtag other-pointer-lowtag
;;; BIND -- Establish VAL as a binding for SYMBOL. Save the old value and
;;; the symbol on the binding stack and stuff the new value into the
;;; symbol.
+;;;
+;;; See the "Chapter 9: Specials" of the SBCL Internals Manual.
(define-vop (bind)
(:args (val :scs (any-reg descriptor-reg))
;;; BIND -- Establish VAL as a binding for SYMBOL. Save the old value and
;;; the symbol on the binding stack and stuff the new value into the
;;; symbol.
+;;; See the "Chapter 9: Specials" of the SBCL Internals Manual.
(define-vop (bind)
(:args (val :scs (any-reg descriptor-reg))
;;; BIND -- Establish VAL as a binding for SYMBOL. Save the old value and
;;; the symbol on the binding stack and stuff the new value into the
;;; symbol.
-
+;;; See the "Chapter 9: Specials" of the SBCL Internals Manual.
#!+sb-thread
(define-vop (bind)
(:args (val :scs (any-reg descriptor-reg))
TLS-VALID
(inst lwzx temp thread-base-tn tls-index)
- (inst addi bsp-tn bsp-tn (* 2 n-word-bytes))
+ (inst addi bsp-tn bsp-tn (* binding-size n-word-bytes))
(storew temp bsp-tn (- binding-value-slot binding-size))
- (storew symbol bsp-tn (- binding-symbol-slot binding-size))
+ (storew tls-index bsp-tn (- binding-symbol-slot binding-size))
(inst stwx val thread-base-tn tls-index)))
#!-sb-thread
(:temporary (:scs (descriptor-reg)) temp)
(:generator 5
(loadw temp symbol symbol-value-slot other-pointer-lowtag)
- (inst addi bsp-tn bsp-tn (* 2 n-word-bytes))
+ (inst addi bsp-tn bsp-tn (* binding-size n-word-bytes))
(storew temp bsp-tn (- binding-value-slot binding-size))
(storew symbol bsp-tn (- binding-symbol-slot binding-size))
(storew val symbol symbol-value-slot other-pointer-lowtag)))
(:temporary (:scs (descriptor-reg)) tls-index value)
(:generator 0
(loadw tls-index bsp-tn (- binding-symbol-slot binding-size))
- (loadw tls-index tls-index symbol-tls-index-slot other-pointer-lowtag)
(loadw value bsp-tn (- binding-value-slot binding-size))
(inst stwx value thread-base-tn tls-index)
(storew zero-tn bsp-tn (- binding-symbol-slot binding-size))
(storew zero-tn bsp-tn (- binding-value-slot binding-size))
- (inst subi bsp-tn bsp-tn (* 2 n-word-bytes))))
+ (inst subi bsp-tn bsp-tn (* binding-size n-word-bytes))))
#!-sb-thread
(define-vop (unbind)
(storew value symbol symbol-value-slot other-pointer-lowtag)
(storew zero-tn bsp-tn (- binding-symbol-slot binding-size))
(storew zero-tn bsp-tn (- binding-value-slot binding-size))
- (inst subi bsp-tn bsp-tn (* 2 n-word-bytes))))
+ (inst subi bsp-tn bsp-tn (* binding-size n-word-bytes))))
(define-vop (unbind-to-here)
(inst beq skip)
(loadw value bsp-tn (- binding-value-slot binding-size))
#!+sb-thread
- (loadw symbol symbol symbol-tls-index-slot other-pointer-lowtag)
- #!+sb-thread
(inst stwx value thread-base-tn symbol)
#!-sb-thread
(storew value symbol symbol-value-slot other-pointer-lowtag)
(emit-label skip)
(storew zero-tn bsp-tn (- binding-value-slot binding-size))
- (inst subi bsp-tn bsp-tn (* 2 n-word-bytes))
+ (inst subi bsp-tn bsp-tn (* binding-size n-word-bytes))
(inst cmpw where bsp-tn)
(inst bne loop)
;;; Establish VAL as a binding for SYMBOL. Save the old value and the
;;; symbol on the binding stack and stuff the new value into the
;;; symbol.
+;;;
+;;; See the "Chapter 9: Specials" of the SBCL Internals Manual.
+
(define-vop (bind)
(:args (val :scs (any-reg descriptor-reg))
(symbol :scs (descriptor-reg)))
;;; BIND -- Establish VAL as a binding for SYMBOL. Save the old value and
;;; the symbol on the binding stack and stuff the new value into the
;;; symbol.
+;;; See the "Chapter 9: Specials" of the SBCL Internals Manual.
#!+sb-thread
(define-vop (bind)
(:args (val :scs (any-reg descriptor-reg))
- (symbol :scs (descriptor-reg)))
- (:temporary (:sc unsigned-reg) tls-index bsp)
+ (symbol :scs (descriptor-reg) :target tmp
+ :to :load))
+ (:temporary (:sc unsigned-reg) tls-index bsp tmp)
(:generator 10
- (let ((tls-index-valid (gen-label)))
- (load-binding-stack-pointer bsp)
- (loadw tls-index symbol symbol-tls-index-slot other-pointer-lowtag)
- (inst add bsp (* binding-size n-word-bytes))
- (store-binding-stack-pointer bsp)
- (inst test tls-index tls-index)
- (inst jmp :ne tls-index-valid)
- (inst mov tls-index symbol)
- (inst mov temp-reg-tn
- (make-fixup (ecase (tn-offset tls-index)
- (#.rax-offset 'alloc-tls-index-in-rax)
- (#.rcx-offset 'alloc-tls-index-in-rcx)
- (#.rdx-offset 'alloc-tls-index-in-rdx)
- (#.rbx-offset 'alloc-tls-index-in-rbx)
- (#.rsi-offset 'alloc-tls-index-in-rsi)
- (#.rdi-offset 'alloc-tls-index-in-rdi)
- (#.r8-offset 'alloc-tls-index-in-r8)
- (#.r9-offset 'alloc-tls-index-in-r9)
- (#.r10-offset 'alloc-tls-index-in-r10)
- (#.r12-offset 'alloc-tls-index-in-r12)
- (#.r13-offset 'alloc-tls-index-in-r13)
- (#.r14-offset 'alloc-tls-index-in-r14)
- (#.r15-offset 'alloc-tls-index-in-r15))
- :assembly-routine))
- (inst call temp-reg-tn)
- (emit-label tls-index-valid)
- (inst push (make-ea :qword :base thread-base-tn :scale 1 :index tls-index))
- (popw bsp (- binding-value-slot binding-size))
- (storew symbol bsp (- binding-symbol-slot binding-size))
- (inst mov (make-ea :qword :base thread-base-tn :scale 1 :index tls-index)
- val))))
+ (load-binding-stack-pointer bsp)
+ (loadw tls-index symbol symbol-tls-index-slot other-pointer-lowtag)
+ (inst add bsp (* binding-size n-word-bytes))
+ (store-binding-stack-pointer bsp)
+ (inst test tls-index tls-index)
+ (inst jmp :ne TLS-INDEX-VALID)
+ (inst mov tls-index symbol)
+ (inst mov tmp
+ (make-fixup (ecase (tn-offset tls-index)
+ (#.rax-offset 'alloc-tls-index-in-rax)
+ (#.rcx-offset 'alloc-tls-index-in-rcx)
+ (#.rdx-offset 'alloc-tls-index-in-rdx)
+ (#.rbx-offset 'alloc-tls-index-in-rbx)
+ (#.rsi-offset 'alloc-tls-index-in-rsi)
+ (#.rdi-offset 'alloc-tls-index-in-rdi)
+ (#.r8-offset 'alloc-tls-index-in-r8)
+ (#.r9-offset 'alloc-tls-index-in-r9)
+ (#.r10-offset 'alloc-tls-index-in-r10)
+ (#.r12-offset 'alloc-tls-index-in-r12)
+ (#.r13-offset 'alloc-tls-index-in-r13)
+ (#.r14-offset 'alloc-tls-index-in-r14)
+ (#.r15-offset 'alloc-tls-index-in-r15))
+ :assembly-routine))
+ (inst call tmp)
+ TLS-INDEX-VALID
+ (inst mov tmp (make-ea :qword :base thread-base-tn :scale 1 :index tls-index))
+ (storew tls-index bsp (- binding-symbol-slot binding-size))
+ (storew tmp bsp (- binding-value-slot binding-size))
+ (inst mov (make-ea :qword :base thread-base-tn :scale 1 :index tls-index)
+ val)))
#!-sb-thread
(define-vop (bind)
(:temporary (:sc unsigned-reg) temp bsp tls-index)
(:generator 0
(load-binding-stack-pointer bsp)
- ;; Load SYMBOL from stack, and get the TLS-INDEX
- (loadw temp bsp (- binding-symbol-slot binding-size))
- (loadw tls-index temp symbol-tls-index-slot other-pointer-lowtag)
- ;; Load VALUE from stack, the restore it to the TLS area.
- (loadw temp bsp (- binding-value-slot binding-size))
+ (inst sub bsp (* binding-size n-word-bytes))
+ ;; Load TLS-INDEX of the SYMBOL from stack
+ (loadw tls-index bsp binding-symbol-slot)
+ ;; Load VALUE from stack, then restore it to the TLS area.
+ (loadw temp bsp binding-value-slot)
(inst mov (make-ea :qword :base thread-base-tn :scale 1 :index tls-index)
temp)
;; Zero out the stack.
- (storew 0 bsp (- binding-symbol-slot binding-size))
- (storew 0 bsp (- binding-value-slot binding-size))
- (inst sub bsp (* binding-size n-word-bytes))
+ (zeroize temp)
+
+ (storew temp bsp binding-symbol-slot)
+ (storew temp bsp binding-value-slot)
(store-binding-stack-pointer bsp)))
#!-sb-thread
(define-vop (unbind-to-here)
(:args (where :scs (descriptor-reg any-reg)))
- (:temporary (:sc unsigned-reg) symbol value bsp #!+sb-thread tls-index)
+ (:temporary (:sc unsigned-reg) symbol value bsp zero)
(:generator 0
(load-binding-stack-pointer bsp)
(inst cmp where bsp)
(inst jmp :e DONE)
-
+ (zeroize zero)
LOOP
- (loadw symbol bsp (- binding-symbol-slot binding-size))
+ (inst sub bsp (* binding-size n-word-bytes))
+ ;; on sb-thread symbol is actually a tls-index
+ (loadw symbol bsp binding-symbol-slot)
(inst test symbol symbol)
(inst jmp :z SKIP)
;; Bind stack debug sentinels have the unbound marker in the symbol slot
(inst cmp symbol unbound-marker-widetag)
(inst jmp :eq SKIP)
- (loadw value bsp (- binding-value-slot binding-size))
+ (loadw value bsp binding-value-slot)
#!-sb-thread
(storew value symbol symbol-value-slot other-pointer-lowtag)
#!+sb-thread
- (loadw tls-index symbol symbol-tls-index-slot other-pointer-lowtag)
- #!+sb-thread
- (inst mov (make-ea :qword :base thread-base-tn :scale 1 :index tls-index)
+ (inst mov (make-ea :qword :base thread-base-tn :scale 1 :index symbol)
value)
- (storew 0 bsp (- binding-symbol-slot binding-size))
+ (storew zero bsp binding-symbol-slot)
SKIP
- (storew 0 bsp (- binding-value-slot binding-size))
- (inst sub bsp (* binding-size n-word-bytes))
+ (storew zero bsp binding-value-slot)
+
(inst cmp where bsp)
(inst jmp :ne LOOP)
(store-binding-stack-pointer bsp)
;;; BIND -- Establish VAL as a binding for SYMBOL. Save the old value and
;;; the symbol on the binding stack and stuff the new value into the
;;; symbol.
-
+;;; See the "Chapter 9: Specials" of the SBCL Internals Manual.
+;;
;;; FIXME: Split into DYNBIND and BIND: DYNBIND needs to ensure
;;; TLS-INDEX, whereas BIND should assume it is already in place. Make
;;; LET &co compile into BIND, and PROGV into DYNBIND, plus ensure
(symbol :scs (descriptor-reg)))
(:temporary (:sc unsigned-reg) tls-index bsp)
(:generator 10
- (let ((tls-index-valid (gen-label)))
- (load-binding-stack-pointer bsp)
- (loadw tls-index symbol symbol-tls-index-slot other-pointer-lowtag)
- (inst add bsp (* binding-size n-word-bytes))
- (store-binding-stack-pointer bsp)
- (inst test tls-index tls-index)
- (inst jmp :ne tls-index-valid)
- (inst mov tls-index symbol)
- (inst call (make-fixup
- (ecase (tn-offset tls-index)
- (#.eax-offset 'alloc-tls-index-in-eax)
- (#.ebx-offset 'alloc-tls-index-in-ebx)
- (#.ecx-offset 'alloc-tls-index-in-ecx)
- (#.edx-offset 'alloc-tls-index-in-edx)
- (#.edi-offset 'alloc-tls-index-in-edi)
- (#.esi-offset 'alloc-tls-index-in-esi))
- :assembly-routine))
- (emit-label tls-index-valid)
- (with-tls-ea (EA :base tls-index :base-already-live-p t)
- (inst push EA :maybe-fs)
- (popw bsp (- binding-value-slot binding-size))
- (storew symbol bsp (- binding-symbol-slot binding-size))
- (inst mov EA val :maybe-fs)))))
+ (load-binding-stack-pointer bsp)
+ (loadw tls-index symbol symbol-tls-index-slot other-pointer-lowtag)
+ (inst add bsp (* binding-size n-word-bytes))
+ (store-binding-stack-pointer bsp)
+ (inst test tls-index tls-index)
+ (inst jmp :ne tls-index-valid)
+ (inst mov tls-index symbol)
+ (inst call (make-fixup
+ (ecase (tn-offset tls-index)
+ (#.eax-offset 'alloc-tls-index-in-eax)
+ (#.ebx-offset 'alloc-tls-index-in-ebx)
+ (#.ecx-offset 'alloc-tls-index-in-ecx)
+ (#.edx-offset 'alloc-tls-index-in-edx)
+ (#.edi-offset 'alloc-tls-index-in-edi)
+ (#.esi-offset 'alloc-tls-index-in-esi))
+ :assembly-routine))
+ TLS-INDEX-VALID
+ (with-tls-ea (EA :base tls-index :base-already-live-p t)
+ (inst push EA :maybe-fs)
+ (popw bsp (- binding-value-slot binding-size))
+ (storew tls-index bsp (- binding-symbol-slot binding-size))
+ (inst mov EA val :maybe-fs))))
#!-sb-thread
(define-vop (bind)
(:generator 0
(load-binding-stack-pointer bsp)
;; Load SYMBOL from stack, and get the TLS-INDEX.
- (loadw temp bsp (- binding-symbol-slot binding-size))
- (loadw tls-index temp symbol-tls-index-slot other-pointer-lowtag)
+ (loadw tls-index bsp (- binding-symbol-slot binding-size))
;; Load VALUE from stack, then restore it to the TLS area.
(loadw temp bsp (- binding-value-slot binding-size))
(with-tls-ea (EA :base tls-index :base-already-live-p t)
(inst mov EA temp :maybe-fs))
;; Zero out the stack.
- (storew 0 bsp (- binding-symbol-slot binding-size))
- (storew 0 bsp (- binding-value-slot binding-size))
(inst sub bsp (* binding-size n-word-bytes))
+ (storew 0 bsp binding-symbol-slot)
+ (storew 0 bsp binding-value-slot)
(store-binding-stack-pointer bsp)))
#!-sb-thread
(define-vop (unbind-to-here)
(:args (where :scs (descriptor-reg any-reg)))
- (:temporary (:sc unsigned-reg) symbol value bsp #!+sb-thread tls-index)
+ (:temporary (:sc unsigned-reg) symbol value bsp)
(:generator 0
(load-binding-stack-pointer bsp)
(inst cmp where bsp)
(inst jmp :e done)
LOOP
- (loadw symbol bsp (- binding-symbol-slot binding-size))
+ (inst sub bsp (* binding-size n-word-bytes))
+ (loadw symbol bsp binding-symbol-slot)
(inst test symbol symbol)
(inst jmp :z skip)
;; Bind stack debug sentinels have the unbound marker in the symbol slot
(inst cmp symbol unbound-marker-widetag)
(inst jmp :eq skip)
- (loadw value bsp (- binding-value-slot binding-size))
+ (loadw value bsp binding-value-slot)
#!-sb-thread (storew value symbol symbol-value-slot other-pointer-lowtag)
-
- #!+sb-thread (loadw
- tls-index symbol symbol-tls-index-slot other-pointer-lowtag)
- #!+sb-thread (with-tls-ea (EA :base tls-index :base-already-live-p t)
+ #!+sb-thread (with-tls-ea (EA :base symbol :base-already-live-p t)
(inst mov EA value :maybe-fs))
- (storew 0 bsp (- binding-symbol-slot binding-size))
+ (storew 0 bsp binding-symbol-slot)
SKIP
- (storew 0 bsp (- binding-value-slot binding-size))
- (inst sub bsp (* binding-size n-word-bytes))
+ (storew 0 bsp binding-value-slot)
(inst cmp where bsp)
(inst jmp :ne loop)
(store-binding-stack-pointer bsp)
/*
* support for dynamic binding from C
+ * See the "Chapter 9: Specials" of the SBCL Internals Manual.
*/
/*
if (get_pseudo_atomic_interrupted(thread))
do_pending_interrupt();
}
+ binding->symbol = sym->tls_index;
+ binding->value = SymbolTlValue(symbol, thread);
}
-#endif
- binding->value = SymbolTlValue(symbol, thread);
+#else
binding->symbol = symbol;
+ binding->value = SymbolTlValue(symbol, thread);
+#endif
SetTlSymbolValue(symbol, value, thread);
}
binding = ((struct binding *)get_binding_stack_pointer(thread)) - 1;
+ /* On sb-thread, it's actually a tls-index */
symbol = binding->symbol;
- SetTlSymbolValue(symbol, binding->value,thread);
-
- binding->symbol = 0;
- binding->value = 0;
-
- set_binding_stack_pointer(thread,binding);
-}
-
-void
-unbind_variable(lispobj name, void *th)
-{
- struct thread *thread=(struct thread *)th;
- struct binding *binding;
- lispobj symbol;
-
- binding = ((struct binding *)get_binding_stack_pointer(thread)) - 1;
-
- symbol = binding->symbol;
-
- if (symbol != name)
- lose("unbind_variable, 0x%p != 0x%p", symbol, name);
+#ifdef LISP_FEATURE_SB_THREAD
- SetTlSymbolValue(symbol, binding->value,thread);
+ ((union per_thread_data *)thread)->dynamic_values[(symbol) >> WORD_SHIFT]
+ = binding->value;
+#else
+ SetSymbolValue(symbol, binding->value, thread);
+#endif
binding->symbol = 0;
binding->value = 0;
symbol = binding->symbol;
if (symbol) {
if (symbol != UNBOUND_MARKER_WIDETAG) {
- SetTlSymbolValue(symbol, binding->value,thread);
+#ifdef LISP_FEATURE_SB_THREAD
+ ((union per_thread_data *)thread)->dynamic_values[(symbol) >> WORD_SHIFT]
+ = binding->value;
+#else
+ SetSymbolValue(symbol, binding->value, thread);
+#endif
}
binding->symbol = 0;
binding->value = 0;
extern void bind_variable(lispobj symbol, lispobj value,void *thread);
extern void unbind(void *thread);
-extern void unbind_variable(lispobj name, void *thread);
extern void unbind_to_here(lispobj *bsp,void *thread);
#endif
block_deferrable_signals(NULL,&sigset);
if(SymbolTlValue(GC_PENDING,self)==T)
gc_happened = funcall0(StaticSymbolFunction(SUB_GC));
- unbind_variable(IN_SAFEPOINT,self);
+ unbind(self);
thread_sigmask(SIG_SETMASK,&sigset,NULL);
if (gc_happened == T) {
/* POST_GC wants to enable interrupts */
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