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Chez Scheme: on Arm64, implement popcount with CNT and ADDV

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Initial measurements suggest that performance is unchanged, but it
at least generates less code.
This commit is contained in:
Matthew Flatt 2020-08-04 16:25:11 +00:00
parent 204d9d6f01
commit 2b73b20704
2 changed files with 40 additions and 1 deletions
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1
racket/src/ChezScheme/s/arm64.def
View File

@ -10,3 +10,4 @@
(define-constant unaligned-floats #f)
(define-constant unaligned-integers #t)
(define-constant integer-divide-instruction #t)
(define-constant popcount-instruction #t)

40
racket/src/ChezScheme/s/arm64.ss
View File

@ -296,6 +296,11 @@
[(op (z ur) (x ur) (y imm-constant ur))
`(set! ,(make-live-info) ,z (asm ,info ,(asm-shiftop op) ,x ,y))])
(define-instruction value popcount
[(op (z ur) (x ur))
(let ([u (make-tmp 'u 'fp)])
`(set! ,(make-live-info) ,z (asm ,info ,asm-popcount ,x ,u)))])
(define-instruction value (move)
[(op (z mem) (x ur))
`(set! ,(make-live-info) ,z ,x)]
@ -687,7 +692,7 @@
(module asm-module (; required exports
asm-move asm-move/extend asm-load asm-store asm-swap asm-library-call asm-library-call! asm-library-jump
asm-mul asm-smulh asm-div asm-add asm-sub asm-logand asm-logor asm-logxor
asm-pop-multiple asm-shiftop asm-logand asm-lognot asm-cmp/asr63
asm-pop-multiple asm-shiftop asm-logand asm-lognot asm-cmp/asr63 asm-popcount
asm-logtest asm-fp-relop asm-relop asm-push-multiple asm-push-fpmultiple asm-pop-fpmultiple
asm-indirect-jump asm-literal-jump
asm-direct-jump asm-return-address asm-jump asm-conditional-jump
@ -809,6 +814,9 @@
(define-op sdiv div-op)
(define-op cnt cnt-op)
(define-op addv.b addv.b-op)
;; scaled variants (offset must be aligned):
(define-op ldri load-imm-op 3 #b11 #b0 #b01) ; selectors are at bits 30 (size), 26, and 22 (opc)
(define-op ldrbi load-imm-op 0 #b00 #b0 #b01)
@ -1107,6 +1115,28 @@
[5 (ax-ea-reg-code src0)]
[0 (ax-ea-reg-code dest)])))
(define cnt-op
(lambda (op dest src code*)
(emit-code (op dest src code*)
[29 #b000]
[24 #b01110]
[22 #b00] ; size
[17 #b10000]
[10 #b0010110]
[5 (ax-ea-reg-code src)]
[0 (ax-ea-reg-code dest)])))
(define addv.b-op
(lambda (op dest src code*)
(emit-code (op dest src code*)
[29 #b000]
[24 #b01110]
[22 #b00] ; size: 00 => b
[17 #b11000]
[10 #b1101110]
[5 (ax-ea-reg-code src)]
[0 (ax-ea-reg-code dest)])))
(define load-imm-op
(lambda (op scale size kind opc dest src imm code*)
(emit-code (op dest src imm code*)
@ -2310,6 +2340,14 @@
(Trivit (dest src)
(emit mvn dest src code*))))
(define asm-popcount
(lambda (code* dest src tmp)
(Trivit (dest src tmp)
(emit fmov.g->f tmp src
(emit cnt tmp tmp
(emit addv.b tmp tmp
(emit fmov.f->g dest tmp code*)))))))
(define asm-enter values)
(define-who asm-inc-cc-counter