1.0.23.37: more CLOS and classoid thread safety

[sbcl.git] / doc / manual / compiler.texinfo

diff --git a/doc/manual/compiler.texinfo b/doc/manual/compiler.texinfo
index 729865f..9a3533d 100644 (file)
--- a/doc/manual/compiler.texinfo
+++ b/doc/manual/compiler.texinfo
@@ -16,6 +16,7 @@ separate that they have their own chapter, @ref{Efficiency}.
 * Compiler Policy::             
 * Compiler Errors::             
 * Open Coding and Inline Expansion::  
+* Interpreter::
 @end menu
 
 @node  Diagnostic Messages
@@ -83,6 +84,9 @@ controlled via the alist
 
 @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? 
@@ -512,21 +516,27 @@ selectable via @code{optimize} declarations.
 
 @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{(and unsigned-byte fixnum)} is simplified into @code{fixnum}.
+
+@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{(< 0 safety (max speed space compilation-speed)}.
+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
@@ -1088,3 +1098,20 @@ open-coded. Even when not open-coded, a call to a standard function
 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
+@vindex sb-ext:*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.
+
+Switching between the compiler and the interpreter is done using the
+special variable @code{sb-ext:*evaluator-mode*}. As of 0.9.17, valid
+values for @code{sb-ext:*evaluator-mode*} are @code{:compile} and
+@code{:interpret}.