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- Log ----------------------------------------------------------------- commit d1af0b85c857baaa7bab870b22590b7b44486a7f Author: Raymond Toy toy.raymond@gmail.com Date: Mon Feb 18 16:17:24 2013 -0800

Optimize TRUNCATE when the second arg is a compile-time constant.

diff --git a/src/compiler/x86/arith.lisp b/src/compiler/x86/arith.lisp index 5751abb..6739f9b 100644 --- a/src/compiler/x86/arith.lisp +++ b/src/compiler/x86/arith.lisp @@ -474,6 +474,7 @@ (inst lea quo (make-ea :dword :index eax :scale 4))) (move rem edx)))

+#+nil (define-vop (fast-truncate-c/fixnum=>fixnum fast-safe-arith-op) (:translate truncate) (:args (x :scs (any-reg) :target eax)) @@ -527,6 +528,7 @@ (move quo eax) (move rem edx)))

+#+nil (define-vop (fast-truncate-c/unsigned=>unsigned fast-safe-arith-op) (:translate truncate) (:args (x :scs (unsigned-reg) :target eax)) @@ -551,6 +553,44 @@ (move quo eax) (move rem edx)))

+(define-vop (fast-truncate-c/unsigned=>unsigned fast-unsigned-binop-c) + (:translate truncate) + (:args (x :scs (unsigned-reg))) + (:info y) + (:arg-types unsigned-num (:constant (integer 2 #.(1- (ash 1 vm:word-bits))))) + (:results (r :scs (unsigned-reg)) + (rem :scs (unsigned-reg))) + (:result-types unsigned-num unsigned-num) + (:note "inline (unsigned-byte 32) arithmetic") + (:temporary (:sc unsigned-reg :offset edx-offset) edx) + (:temporary (:sc unsigned-reg :offset eax-offset) eax) + (:generator 6 + (multiple-value-bind (recip shift overflowp) + (c::find-unsigned-reciprocal y vm:word-bits) + ;; q = floor(M*x/2^32) + (inst mov eax recip) + (inst mul eax x) ; edx:eax = x*recip + (cond (overflowp + ;; The case where the sum overflows. X86 has a rotate + ;; with carry instruction so use that to get the MSB of + ;; the sum and then a regular shift to get the correct + ;; number of shifts. + (inst add edx x) + (inst rcr edx 1) + (when (> shift 1) + (inst shr edx (1- shift)))) + (t + ;; The easy case + (unless (zerop shift) + (inst shr edx shift)))) + ;; Compute the remainder + (move rem x) ; Save x in case r is the same tn + (move r edx) + (move eax edx) + (inst mov edx y) + (inst mul eax edx) + (inst sub rem eax)))) + (define-vop (fast-truncate/signed=>signed fast-safe-arith-op) (:translate truncate) (:args (x :scs (signed-reg) :target eax) @@ -578,6 +618,7 @@ (move quo eax) (move rem edx)))

+#+nil (define-vop (fast-truncate-c/signed=>signed fast-safe-arith-op) (:translate truncate) (:args (x :scs (signed-reg) :target eax)) @@ -602,6 +643,43 @@ (move quo eax) (move rem edx)))

+(define-vop (fast-truncate-c/signed=>signed fast-signed-binop-c) + (:translate truncate) + (:args (x :scs (signed-reg))) + (:info y) + (:arg-types signed-num (:constant (integer 2 #.(1- (ash 1 vm:word-bits))))) + (:results (r :scs (signed-reg)) + (rem :scs (signed-reg))) + (:result-types signed-num signed-num) + (:note "inline (signed-byte 32) arithmetic") + (:temporary (:sc signed-reg :offset edx-offset) edx) + (:temporary (:sc signed-reg :offset eax-offset) eax) + (:generator 13 + (multiple-value-bind (recip shift) + (c::find-signed-reciprocal y vm:word-bits) + ;; Compute q = floor(M*n/2^32). That is, the high half of the + ;; product. + (inst mov eax recip) + (inst imul x) ; edx:eax = x * recip + ;; Adjust if the M is negative. + (when (minusp recip) + (inst add edx x)) + ;; Shift quotient as needed. + (unless (zerop shift) + (inst sar edx shift)) + ;; Add one to quotient if X is negative. This is done by right + ;; shifting X to give either -1 or 0. Then subtract this from + ;; the quotient. (NOTE: in the book, the sample code has this + ;; wrong and ADDS instead of SUBTRACTS.) + (move eax x) + (inst sar eax 31) + (inst sub edx eax) + + ;; Now compute the remainder. + (move rem x) + (move r edx) ; Save quotient for return + (inst imul edx y) ; edx = q * y + (inst sub rem edx))))

;;;; Shifting diff --git a/src/general-info/release-20e.txt b/src/general-info/release-20e.txt index e5b7331..8d14c58 100644 --- a/src/general-info/release-20e.txt +++ b/src/general-info/release-20e.txt @@ -31,7 +31,9 @@ New in this release: * The sparc port can be built using gcc once again. * The old Cheney stop-and-copy GC supported on sparc once again. However, there are no plans on supplying sparc binaries with - this GC. + this GC. + * For x86, optimize TRUNCATE when the second arg is a compile-time + constant. (Sparc and ppc already had this optimization)

* ANSI compliance fixes:

-----------------------------------------------------------------------

Summary of changes: src/compiler/x86/arith.lisp | 78 ++++++++++++++++++++++++++++++++++++++ src/general-info/release-20e.txt | 4 +- 2 files changed, 81 insertions(+), 1 deletions(-)

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