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continuing to clean up the emitted code.

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This commit is contained in:
Danny Yoo 2011-09-06 16:29:20 -04:00
parent a3b0a1755a
commit 64e66eaf28
2 changed files with 48 additions and 8 deletions
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21
compiler/il-structs.rkt
View File

@ -97,11 +97,22 @@
(define (new-SubtractArg lhs rhs)
;; FIXME: do some limited constant folding here
(cond
[(and (Const? lhs) (number? lhs)
(Const? rhs) (number? rhs))
(make-Const (- lhs rhs))]
[(and (Const? rhs) (number? rhs) (= rhs 0))
lhs]
[(and (Const? lhs)(Const? rhs))
(let ([lhs-val (Const-const lhs)]
[rhs-val (Const-const rhs)])
(cond [(and (number? lhs-val)
(number? rhs-val))
(make-Const (- lhs-val rhs-val))]
[else
(make-SubtractArg lhs rhs)]))]
[(Const? rhs)
(let ([rhs-val (Const-const rhs)])
(cond
[(and (number? rhs-val)
(= rhs-val 0))
lhs]
[else
(make-SubtractArg lhs rhs)]))]
[else
(make-SubtractArg lhs rhs)]))

35
compiler/optimize-il.rkt
View File

@ -18,7 +18,7 @@
;; For now, replace pairs of PushEnvironment / AssignImmediate(0, ...)
;; We should do some more optimizations here, like peephole...
(let* ([statements (filter not-no-op? statements)]
[statements (eliminate-no-ops statements)]
[statements (pairwise-reductions statements)]
[statements (flatten-adjacent-labels statements)])
statements))
@ -302,8 +302,8 @@
(: eliminate-no-ops ((Listof Statement) -> (Listof Statement)))
(define (eliminate-no-ops statements)
(: pairwise-reductions ((Listof Statement) -> (Listof Statement)))
(define (pairwise-reductions statements)
(let loop ([statements statements])
(cond
[(empty? statements)
@ -319,6 +319,9 @@
[else
(let ([second-stmt (second statements)])
(cond
;; A PushEnvironment followed by a direct AssignImmediate can be reduced to a single
;; instruction.
[(and (PushEnvironment? first-stmt)
(equal? first-stmt (make-PushEnvironment 1 #f))
(AssignImmediateStatement? second-stmt))
@ -332,6 +335,32 @@
(loop (rest (rest statements))))]
[else
(default)]))]
;; Adjacent PopEnvironments with constants can be reduced to single ones
[(and (PopEnvironment? first-stmt)
(PopEnvironment? second-stmt))
(let ([first-n (PopEnvironment-n first-stmt)]
[second-n (PopEnvironment-n second-stmt)]
[first-skip (PopEnvironment-skip first-stmt)]
[second-skip (PopEnvironment-skip first-stmt)])
(cond [(and (Const? first-n) (Const? second-n) (Const? first-skip) (Const? second-skip))
(let ([first-n-val (Const-const first-n)]
[second-n-val (Const-const second-n)]
[first-skip-val (Const-const first-skip)]
[second-skip-val (Const-const second-skip)])
(cond
[(and (number? first-n-val)
(number? second-n-val)
(number? first-skip-val) (= first-skip-val 0)
(number? second-skip-val) (= second-skip-val 0))
(loop (cons (make-PopEnvironment (make-Const (+ first-n-val second-n-val))
(make-Const 0))
(rest (rest statements))))]
[else
(default)]))]
[else
(default)]))]
[else
(default)]))]))])))