New contrib: SB-GMP

 This contrib was developed by Stephan Frank to replace some of our
 bignum and rational arithmetic code with calls to libgmp.  Simply
 loading the contrib will transparently accelerate arithmetic on
 large rationals when libgmp is available; if libgmp cannot be found,
 the contrib should change nothing.

 The contrib also wraps additional functions in GNU MP, so that they
 accept and return SBCL-native integers or ratios.  See GNU MP's manual
 for more information.

CREDITS

@@ -588,6 +588,10 @@ Andreas Fuchs:
   regressions of SBCL.  He assisted with the integration of the
   Unicode work.
 
+Stephan Frank:
+  He contributed the SB-GMP contrib to exploit libgmp in bignum and
+  ratio arithmetic.
+
 Nathan Froyd:
   He has fixed various bugs, and also done a lot of internal
   cleanup, not visible at the user level but important for
@@ -856,6 +860,7 @@ NS   Nikodemus Siivola
 PFD  Paul F. Dietz
 PRM  Pierre Mai
 PVE  Peter Van Eynde
+PK/PVK Paul-Virak Khuong
 PW   Paul Werkowski
 RAM  Robert MacLachlan
 RLT  Raymond Toy

NEWS

@@ -1,5 +1,7 @@
 ;;;; -*- coding: utf-8; fill-column: 78 -*-
 changes relative to sbcl-1.1.8:
+  * new feature: the contrib SB-GMP links with libgmp at runtime to speed
+    up arithmetic on bignums and ratios.  (contributed by Stephan Frank)
   * enhancement: disassemble now annotates some previously missing static
     functions, like LENGTH.
   * enhancement: clean.sh now also cleans doc/internals.

contrib/sb-gmp/Makefile

@@ -0,0 +1,2 @@
+SYSTEM=sb-gmp
+include ../asdf-module.mk

contrib/sb-gmp/README.md

@@ -0,0 +1,39 @@
+SB-GMP
+======
+
+GMP integration for SBCL
+
+This contrib enables the use of bignum computation routines from the
+GMP library for SBCL internal bignum calculations.
+
+Some functions can be transparently replaced within SBCL, namely:
+
+ - sb-bignum:multiply-bignum
+ - sb-bignum:bignum-truncate
+ - sb-bignum:bignum-gcd
+ - sb-kernel::two-arg-lcm
+ - cl:isqrt
+
+and for making use of the GMP rational arithmetic:
+
+ - sb-kernel::two-arg-+
+ - sb-kernel::two-arg--
+ - sb-kernel::two-arg-*
+ - sb-kernel::two-arg-/
+
+Most of the other SBCL bignum routines rely on these functions for the
+heavy computational lifting.
+
+However, SB-GMP also provides easy and transparent access to several
+other functions of the GMP library and may be able to replace other
+parts of the SBCL bignum machinery in the future. Refer to the GMP
+documentation for the respective function specification.
+
+The transparent SBCL integration is automatically activated by loading
+SB-GMP.  Some care is taken to behave correctly across core saves and
+loads; however, if this does not work correctly, `SB-GMP:UNLOAD-GMP`
+and `SB-GMP:LOAD-GMP` can be called to explicitly unload and reload
+libgmp and uninstall/reinstall the hooks.  The hooks can also be
+directly uninstalled and installed with `SB-GMP:UNINSTALL-GMP-FUNS`
+and `SB-GMP:INSTALL-GMP-FUNS`.  However, in most cases, binding
+`SB-GMP:*GMP-DISABLED*` to `T` should suffice.