Raymond Toy pushed to branch master at cmucl / cmucl Commits: 5d3a63fa by Raymond Toy at 2015-11-28T16:43:54Z Support constant shifts for bignum digits. This gets rid of the load of the shift amount to ecx, saving one instruction and reducing pressure on the ecx register. - - - - - 1 changed file: - src/compiler/x86/arith.lisp Changes: ===================================== src/compiler/x86/arith.lisp ===================================== --- a/src/compiler/x86/arith.lisp +++ b/src/compiler/x86/arith.lisp @@ -1445,31 +1445,43 @@ (:translate bignum::%ashr) (:policy :fast-safe) (:args (digit :scs (unsigned-reg unsigned-stack) :target result) - (count :scs (unsigned-reg) :target ecx)) + (count :scs (unsigned-reg immediate))) (:arg-types unsigned-num positive-fixnum) (:temporary (:sc unsigned-reg :offset ecx-offset :from (:argument 1)) ecx) (:results (result :scs (unsigned-reg) :from (:argument 0) :load-if (not (and (sc-is result unsigned-stack) (location= digit result))))) (:result-types unsigned-num) - (:generator 1 + (:generator 2 (move result digit) - (move ecx count) - (inst sar result :cl))) + (sc-case count + (unsigned-reg + (move ecx count) + (inst sar result :cl)) + (immediate + (inst sar result (tn-value count)))))) (define-vop (digit-lshr digit-ashr) (:translate bignum::%digit-logical-shift-right) - (:generator 1 + (:generator 2 (move result digit) - (move ecx count) - (inst shr result :cl))) + (sc-case count + (unsigned-reg + (move ecx count) + (inst shr result :cl)) + (immediate + (inst shr result (tn-value count)))))) (define-vop (digit-ashl digit-ashr) (:translate bignum::%ashl) - (:generator 1 + (:generator 2 (move result digit) - (move ecx count) - (inst shl result :cl))) + (sc-case count + (unsigned-reg + (move ecx count) + (inst shl result :cl)) + (immediate + (inst shl result (tn-value count))))))  ;;;; Static functions. View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/commit/5d3a63fa223ea40f8625a47d36...