separate that they have their own chapter, @ref{Efficiency}.
@menu
-* Diagnostic Messages::
+* Diagnostic Messages::
* Handling of Types::
* Compiler Policy::
* Compiler Errors::
* Open Coding and Inline Expansion::
+* Interpreter::
@end menu
@node Diagnostic Messages
(* x -5))))
@end lisp
-@deffn {Declaration} sb-ext:muffle-conditions
+@deffn {Declaration} @sbext{muffle-conditions}
Syntax: type*
Muffles the diagnostic messages that would be caused by compile-time
signals of given types.
@end deffn
-@deffn {Declaration} sb-ext:unmuffle-conditions
+@deffn {Declaration} @sbext{unmuffle-conditions}
Syntax: type*
-Cancels the effect of a previous @code{sb-ext:muffle-condition}
+Cancels the effect of a previous @code{sb-ext:muffle-conditions}
declaration.
@end deffn
@include var-sb-ext-star-compiler-print-variable-alist-star.texinfo
+For information about muffling warnings signaled outside of the
+compiler, see @ref{Customization Hooks for Users}.
+
@c <!-- FIXME: How much control over error messages is in SBCL?
@c _ How much should be? How much of this documentation should
@c _ we save or adapt?
@comment node-name, next, previous, up
@subsection Diagnostic Severity
@cindex Severity of compiler messages
-@cindex compiler diagnostic severity
-@tindex error
-@tindex warning
-@tindex style-warning
-@tindex compiler-note
-@tindex code-deletion-note
+@cindex Compiler Diagnostic Severity
+@tindex @cl{error}
+@tindex @cl{warning}
+@tindex @cl{style-warning}
+@tindex @sbext{compiler-note}
+@tindex @sbext{code-deletion-note}
There are four levels of compiler diagnostic severity:
too mild for the standard condition classes, typically hints about how
efficiency might be improved. The @code{sb-ext:code-deletion-note}, a
subtype of @code{compiler-note}, is signalled when the compiler
-deletes user-supplied code, usually after proving that the code in
-question is unreachable.
+deletes user-supplied code after proving that the code in question is
+unreachable.
Future work for SBCL includes expanding this hierarchy of types to
allow more fine-grained control over emission of diagnostic messages.
@enumerate
@item
-@findex with-compilation-unit
+@findex @cl{with-compilation-unit}
@samp{file: /tmp/foo.lisp} This is the name of the file that the
compiler read the relevant code from. The file name is displayed
because it may not be immediately obvious when there is an error
@node The Processing Path
@comment node-name, next, previous, up
@subsubsection The Processing Path
-@cindex Processing path
+@cindex Processing Path
@cindex Macroexpansion
@cindex Source-to-source transformation
@comment node-name, next, previous, up
@section Handling of Types
-The most unusual features of the SBCL compiler (which is very
-similar to the original CMUCL compiler, also known as @dfn{Python})
-is its unusually sophisticated understanding of the Common Lisp type
-system and its unusually conservative approach to the implementation
-of type declarations.
+One of the most important features of the SBCL compiler (similar to
+the original CMUCL compiler, also known as @dfn{Python}) is its fairly
+sophisticated understanding of the Common Lisp type system and its
+conservative approach to the implementation of type declarations.
These two features reward the use of type declarations throughout
development, even when high performance is not a concern. Also, as
of appropriate type declarations can be very important for performance
as well.
-@findex satisfies
+@findex @cl{satisfies}
The SBCL compiler also has a greater knowledge of the Common Lisp
type system than other compilers. Support is incomplete only for types
involving the @code{satisfies} type specifier.
@node Declarations as Assertions
@comment node-name, next, previous, up
@subsection Declarations as Assertions
-@findex safety
+@cindex Safety optimization quality
-The SBCL compiler treats type declarations differently from most
-other Lisp compilers. Under default compilation policy the compiler
-doesn't blindly believe type declarations, but considers them
-assertions about the program that should be checked: all type
-declarations that have not been proven to always hold are asserted at
-runtime.
+The SBCL compiler treats type declarations differently from most other
+Lisp compilers. Under default compilation policy the compiler doesn't
+blindly believe type declarations, but considers them assertions about
+the program that should be checked: all type declarations that have
+not been proven to always hold are asserted at runtime.
@quotation
@emph{Remaining bugs in the compiler's handling of types unfortunately
provide some exceptions to this rule, see @ref{Implementation
-Limitations}).}
+Limitations}.}
@end quotation
-There are three type checking policies available in SBCL,
-selectable via @code{optimize} declarations.
+CLOS slot types form a notable exception. Types declared using the
+@code{:type} slot option in @code{defclass} are asserted if and only
+if the class was defined in @emph{safe code} and the slot access
+location is in @emph{safe code} as well. This laxness does not pose
+any internal consistency issues, as the CLOS slot types are not
+available for the type inferencer, nor do CLOS slot types provide any
+efficiency benefits.
+
+There are three type checking policies available in SBCL, selectable
+via @code{optimize} declarations.
@table @strong
@item Full Type Checks
All declarations are considered assertions to be checked at runtime,
-and all type checks are precise.
+and all type checks are precise. The default compilation policy
+provides full type checks.
-Used when @code{(>= safety (max speed space compilation-speed)}. The
-default compilation policy provides full type checks.
+Used when @code{(or (>= safety 2) (>= safety speed 1))}.
@item Weak Type Checks
-Any or all type declarations may be believed without runtime
-assertions, and assertions that are done may be imprecise.
+Declared types may be simplified into faster to check supertypes: for
+example, @code{(or (integer -17 -7) (integer 7 17))} is simplified
+into @code{(integer -17 17)}.
-Used when @code{(< 0 safety (max speed space compilation-speed)}.
+@strong{Note}: it is relatively easy to corrupt the heap when weak
+type checks are used if the program contains type-errors.
+
+Used when @code{(and (< safety 2) (< safety speed))}
@item No Type Checks
All declarations are believed without assertions. Also disables
argument count and array bounds checking.
+@strong{Note}: any type errors in code where type checks are not
+performed are liable to corrupt the heap.
+
Used when @code{(= safety 0)}.
@end table
@c _ In addition to suppressing type checks, \code{0} also suppresses
@c _ argument count checking, unbound-symbol checking and array bounds
@c _ checks.
+@c _ ... and checking of tag existence in RETURN-FROM and GO.
@c _
@c _\item[\code{extensions:inhibit-warnings}] \cindex{inhibit-warnings
@c _ optimization quality}This is a CMU extension that determines how
@c _(end of section on compiler policy)
@c _-->
+@include fun-sb-ext-describe-compiler-policy.texinfo
+@include fun-sb-ext-restrict-compiler-policy.texinfo
+@include macro-common-lisp-with-compilation-unit.texinfo
+
@node Compiler Errors
@comment node-name, next, previous, up
@section Compiler Errors
@comment node-name, next, previous, up
@section Open Coding and Inline Expansion
@cindex Open-coding
-@cindex inline expansion
-@cindex static functions
+@cindex Inline expansion
+@cindex Static functions
Since Common Lisp forbids the redefinition of standard functions, the
compiler can have special knowledge of these standard functions
may be transformed into a different function call (as in the last
example) or compiled as @emph{static call}. Static function call uses
a more efficient calling convention that forbids redefinition.
+
+@node Interpreter
+@comment node-name, next, previous, up
+@section Interpreter
+@cindex Interpreter
+@findex @cl{eval}
+@vindex @sbext{@earmuffs{evaluator-mode}}
+
+By default SBCL implements @code{eval} by calling the native code
+compiler.
+
+SBCL also includes an interpreter for use in special cases where using
+the compiler is undesirable, for example due to compilation overhead.
+Unlike in some other Lisp implementations, in SBCL interpreted code is
+not safer or more debuggable than compiled code.
+
+@include var-sb-ext-star-evaluator-mode-star.texinfo
projects / sbcl.git / blobdiff