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cs: use fxlogtest instead of (fx= 0 (fxand ...))

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For the stencil-vector HAMT implementation, the difference
can be 5-10% improvement on microbenchmarks.
This commit is contained in:
Matthew Flatt 2020-01-24 17:33:47 -07:00
parent 7c06d6d4ab
commit 9d43b62282
1 changed files with 9 additions and 9 deletions
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18
racket/src/cs/rumble/hamt-stencil.ss
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@ -134,7 +134,7 @@
(define (bnode-val-ref n bit)
(let ([mask-bit (fxsll 1 (fx+ bit HAMT-VAL-OFFSET))]
[mask (stencil-vector-mask n)])
(if (fx= 0 (fxand mask-bit mask))
(if (not (fxlogtest mask-bit mask))
#t ; not stored => #t
(stencil-vector-ref n (fxpopcount
(fxand mask (fx- mask-bit 1)))))))
@ -145,7 +145,7 @@
;; assumes no children
(define (bnode-only-val-ref n)
(if (fx= 0 (fxand (stencil-vector-mask n) HAMT-VAL-MASK))
(if (not (fxlogtest (stencil-vector-mask n) HAMT-VAL-MASK))
#t ; not stored => #t
(stencil-vector-ref n (fx+ 1 HAMT-STATIC-FIELD-COUNT))))
@ -234,7 +234,7 @@
(define (bnode-replace-val node bit val)
(let ([val-bit (fxsll 1 (fx+ bit HAMT-VAL-OFFSET))])
(cond
[(fx= 0 (fxand (stencil-vector-mask node) val-bit))
[(not (fxlogtest (stencil-vector-mask node) val-bit))
;; old value was #t
(cond
[(eq? val #t)
@ -253,7 +253,7 @@
[val-bit (fxsll 1 (fx+ bit HAMT-VAL-OFFSET))]
[key+val-bits (fxior key-bit val-bit)])
(cond
[(fx= 0 (fxand (stencil-vector-mask node) val-bit))
[(not (fxlogtest (stencil-vector-mask node) val-bit))
;; old value was #t
(cond
[(eq? val #t)
@ -1070,19 +1070,19 @@
[else
(let ([bm-bit (fxand bm (fxxor bm (fx- bm 1)))]) ; peel off lowest set bit of `bm`
(cond
[(fx= 0 (fxand bm-bit abm))
[(not (fxlogtest bm-bit abm))
;; No key or child in `a`
(cond
[(fx= 0 (fxand bm-bit bcm))
[(not (fxlogtest bm-bit bcm))
;; Key in `b`
(loop (fx- bm bm-bit) aki (fx1+ bki) aci bci)]
[else
;; Child in `b`
(loop (fx- bm bm-bit) aki bki aci (fx1+ bci))])]
[(fx= 0 (fxand bm-bit acm))
[(not (fxlogtest bm-bit acm))
;; Key in `a`
(cond
[(fx= 0 (fxand bm-bit bcm))
[(not (fxlogtest bm-bit bcm))
;; Key in `b`
(and
(hamt-wrapped-key=? (bnode-key-index-ref a aki) (bnode-key-index-ref b bki))
@ -1101,7 +1101,7 @@
[else
;; Child in `a`
(cond
[(fx= 0 (fxand bm-bit bcm))
[(not (fxlogtest bm-bit bcm))
;; Key in `b`, and multiple keys in `a` child means `a` is not a subset
#f]
[else