X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=doc%2Fmanual%2Fefficiency.texinfo;h=6931ed03533bd4f40e7011a7b6e0bd7b91200e7c;hb=543b6b16b50cd4116b699aa5e09cd90d929c2471;hp=7559abf3d4b037f87d84b0439415befd4811c424;hpb=3ff0ba49f86506cd5ad6d5d259fa85a40d83fcb2;p=sbcl.git diff --git a/doc/manual/efficiency.texinfo b/doc/manual/efficiency.texinfo index 7559abf..6931ed0 100644 --- a/doc/manual/efficiency.texinfo +++ b/doc/manual/efficiency.texinfo @@ -1,6 +1,7 @@ -@node Efficiency, Beyond The ANSI Standard, The Debugger, Top +@node Efficiency @comment node-name, next, previous, up @chapter Efficiency +@cindex Efficiency FIXME: The material in the CMUCL manual about getting good performance from the compiler should be reviewed, reformatted in @@ -122,7 +123,7 @@ examples (some straightforward, some less so). * Modular arithmetic:: @end menu -@node Dynamic-extent allocation, Modular arithmetic, Efficiency, Efficiency +@node Dynamic-extent allocation @comment node-name, next, previous, up @section Dynamic-extent allocation @cindex Dynamic-extent declaration @@ -161,15 +162,53 @@ it would not be in the following situation: because both the allocation of the @code{&rest} list and the variable binding are outside the scope of the @code{optimize} declaration. -There are many cases when dynamic-extent declarations could be useful. -At present, SBCL implements +There are many cases when @code{dynamic-extent} declarations could be +useful. At present, SBCL implements -@itemize +@itemize @item Stack allocation of @code{&rest} lists, where these are declared @code{dynamic-extent}. +@item +Stack allocation of @code{list} and @code{list*}, whose result is +bound to a variable, declared @code{dynamic-extent}, such as + +@lisp +(let ((list (list 1 2 3))) + (declare (dynamic-extent list) + ...)) +@end lisp + +or + +@lisp +(flet ((f (x) + (declare (dynamic-extent x)) + ...)) + ... + (f (list 1 2 3)) + ...) +@end lisp + +@item +Stack allocation of simple forms of @code{make-array}, whose result is +bound to a variable, declared @code{dynamic-extent}. The resulting +array should be one-dimensional, the only allowed keyword argument is +@code{:element-type}. + +Notice, that stack space is limited, so allocation of a large vector +may cause stack overflow and abnormal termination of the SBCL process. + +@item +Stack allocation of closures, defined with @code{flet} or +@code{labels} with a bound declaration @code{dynamic-extent}. +Closed-over variables, which are assigned (either inside or outside +the closure) are still allocated on the heap. Blocks and tags are also +allocated on the heap, unless all non-local control transfers to them +are compiled with zero @code{safety}. + @end itemize Future plans include @@ -197,7 +236,7 @@ closure, even when the closure is not declared @code{dynamic-extent}. @end itemize -@node Modular arithmetic, , Dynamic-extent allocation, Efficiency +@node Modular arithmetic @comment node-name, next, previous, up @section Modular arithmetic @cindex Modular arithmetic @@ -231,10 +270,9 @@ with versions cutting results to 32 bits, and because terminals (here---expressions @code{x} and @code{y}) are also of type @code{(unsigned-byte 32)}, 32-bit machine arithmetic can be used. - As of SBCL 0.8.5 ``good'' functions are @code{+}, @code{-}; @code{logand}, @code{logior}, @code{logxor}, @code{lognot} and their combinations; and @code{ash} with the positive second -argument. ``Good'' widths are 32 on HPPA, MIPS, PPC, Sparc and X86 and -64 on Alpha. While it is possible to support smaller widths as well, -currently it is not implemented. +argument. ``Good'' widths are 32 on HPPA, MIPS, PPC, Sparc and x86 and +64 on Alpha. While it is possible to support smaller widths as well, +currently this is not implemented.