X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=base-target-features.lisp-expr;h=10e5d56046bb43f785a7f277c82758c0f1e6d88d;hb=a18f0a95bc9a457e4d2d00c702b746f29c2662b1;hp=43e100929c5bfc5642afb0a036eb48419c7d0573;hpb=6d9ecc45cb21a1208deb8c4d128adc04aa289c9d;p=sbcl.git diff --git a/base-target-features.lisp-expr b/base-target-features.lisp-expr index 43e1009..10e5d56 100644 --- a/base-target-features.lisp-expr +++ b/base-target-features.lisp-expr @@ -2,6 +2,10 @@ ;;;; CL:*FEATURES* in the target SBCL, plus some comments about other ;;;; CL:*FEATURES* tags which have special meaning to SBCL or which ;;;; have a special conventional meaning +;;;; +;;;; Note that the preferred way to customize the features of a local +;;;; build of SBCL is not to edit this file, but to tweak +;;;; customize-target-features.lisp. ;;;; This software is part of the SBCL system. See the README file for ;;;; more information. @@ -74,6 +78,31 @@ ;; you are a developer. :sb-test + ;; :SB-PROPAGATE-FLOAT-TYPE and :SB-PROPAGATE-FUN-TYPE enable + ;; some numeric optimizer code in the target compiler. They + ;; correspond to the :PROPAGATE-FLOAT-TYPE and :PROPAGATE-FUN-TYPE + ;; features in the original CMU CL code, and while documentation + ;; existed for those, it seemed a little inconsistent. Despite the + ;; name, :SB-PROPAGATE-FLOAT-TYPE seems to control not only + ;; floating point optimizations, but some integer optimizations as + ;; well. + ;; + ;; CROSS-FLOAT-INFINITY-KLUDGE: + ;; * Even when these target features are enabled, the optimizations + ;; aren't enabled in the cross-compiler, because some of them + ;; depend on floating point infinities, which aren't in general + ;; supported on the cross-compilation host. + ;; * This is supported by hacking the features out of the + ;; *SHEBANG-FEATURES* list while we're building the cross-compiler. + ;; This is ugly and confusing and weird, but all the alternatives + ;; that I could think of seem messy and error-prone. That doesn't + ;; mean there's not a better way, though. Suggestions are welcome; + ;; or if you'd like to submit patches to make this code work + ;; without requiring floating point infinities, so that the entire + ;; problem goes away, that might be even better! -- WHN 2001-03-22 + :sb-propagate-float-type + :sb-propagate-fun-type + ;; Setting this makes more debugging information available. ;; If you aren't hacking or troubleshooting SBCL itself, you ;; probably don't want this set. @@ -97,7 +126,7 @@ ;; If you want to be able to use the extra debugging information, ;; therefore, be sure to keep the sources around, and run with the ;; readtable configured so that the system sources can be read. - ;:sb-show + ; :sb-show ;; Enable extra debugging output in the assem.lisp assembler/scheduler ;; code. (This is the feature which was called :DEBUG in the @@ -143,60 +172,19 @@ ; :mp ; :mp-i486 - ;; KLUDGE: used to suppress stale code related to floating point infinities. - ;; I intend to delete this code completely some day, since it was a pain - ;; for me to try to work with and since all benefits it provides are - ;; non-portable. Until I actually pull the trigger, though, I've left - ;; various stale code in place protected with #!-SB-INFINITIES. - ; :sb-infinities - ;; This affects the definition of a lot of things in bignum.lisp. It - ;; doesn't seem to be documented anywhere what systems it might apply to. - ;; It doesn't seem to be needed for X86 systems anyway. + ;; doesn't seem to be documented anywhere what systems it might apply + ;; to. It doesn't seem to be needed for X86 systems anyway. ; :32x16-divide - ;; This is probably true for some processor types, but not X86. It affects - ;; a lot of floating point code. + ;; This is probably true for some processor types, but not X86. It + ;; affects a lot of floating point code. ; :negative-zero-is-not-zero - ;; This is mentioned in cmu-user.tex, which says that it enables - ;; the compiler to reason about integer arithmetic. It also seems to - ;; control other fancy numeric reasoning, e.g. knowing the result type of - ;; a remainder calculation given the type of its inputs. - ;; - ;; KLUDGE: Even when this is implemented for the target feature list, - ;; the code to implement this feature will not generated in the - ;; cross-compiler (i.e. will only be generated in the target compiler). - ;; The reason for this is that the interval arithmetic routines used - ;; to implement this feature are written under the assumption that - ;; Lisp arithmetic supports plus and minus infinity, which isn't guaranteed by - ;; ANSI Common Lisp. I've tried to mark the conditionals which implement - ;; this kludge with the string CROSS-FLOAT-INFINITY-KLUDGE so that - ;; sometime it might be possible to undo them (perhaps by using - ;; nice portable :PLUS-INFINITY and :MINUS-INFINITY values instead of - ;; implementation dependent floating infinity values, which would - ;; admittedly involve extra consing; or perhaps by finding some cleaner - ;; way of suppressing the construction of this code in the cross-compiler). - ;; - ;; KLUDGE: Even after doing the KLUDGE above, the cross-compiler doesn't work, - ;; because some interval operations are conditional on PROPAGATE-FUN-TYPE - ;; instead of PROPAGATE-FLOAT-TYPE. So for now, I've completely turned off - ;; both PROPAGATE-FUN-TYPE and PROPAGATE-FLOAT-TYPE. (After I build - ;; a compiler which works, then I can think about getting the optimization - ;; to work.) -- WHN 19990702 - ; :propagate-float-type - - ;; According to cmu-user.tex, this enables the compiler to infer result - ;; types for mathematical functions a la SQRT, EXPT, and LOG, allowing - ;; it to e.g. eliminate the possibility that a complex result will be - ;; generated. - ;; - ;; KLUDGE: turned off as per the comments for PROPAGATE-FLOAT-TYPE above - ; :propagate-fun-type - - ;; It's unclear to me what this does (but it was enabled in the code that I - ;; picked up from Peter Van Eynde). -- WHN 19990224 - :constrain-float-type + ;; It's unclear to me what this does (but it was enabled in the code + ;; that I picked up from Peter Van Eynde, called CONSTRAIN-FLOAT-TYPE + ;; instead of SB-CONSTRAIN-FLOAT-TYPE). -- WHN 19990224 + :sb-constrain-float-type ;; This is set in classic CMU CL, and presumably there it means ;; that the floating point arithmetic implementation