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Add constant folding for purely constant operations

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John Lorentzson 2025-07-31 12:45:24 +02:00
parent 502451af8b
commit 4c3a25d5e6
2 changed files with 30 additions and 0 deletions
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1
user-side-compiler/interface.lisp
View file

@ -65,6 +65,7 @@
(defun ci-optimize-ir (start-iblock)
(do-iblocks (ib start-iblock)
(optim-reorder-arguments ib)
(optim-trivial-constant-folding ib)
(optim-call-duplicate-args ib)
(optim-remove-unused ib)))

29
user-side-compiler/middle/optimizations.lisp
View file

@ -29,6 +29,35 @@
(when add-post
(list output))))))
(defun optim-trivial-constant-folding (iblock)
"Replaces operations taking two constants with the result."
(declare (optimize (debug 3)))
(let ((folders
`((ir-plus . ,(lambda (x y) (ldb (byte 8 0) (+ x y))))
(ir-minus . ,(lambda (x y) (ldb (byte 8 0) (- x y))))
(ir-mult . ,(lambda (x y) (ldb (byte 8 0) (* x y))))
(ir-div . ,(lambda (x y) (ldb (byte 8 0) (floor (/ x y)))))
(ir-test-equal . ,(lambda (x y) (if (= x y) 1 0)))
(ir-test-not-equal . ,(lambda (x y) (if (/= x y) 1 0)))
(ir-test-less . ,(lambda (x y) (if (< x y) 1 0)))
(ir-test-less-or-equal . ,(lambda (x y) (if (<= x y) 1 0)))
(ir-test-greater . ,(lambda (x y) (if (> x y) 1 0)))
(ir-test-greater-or-equal . ,(lambda (x y) (if (>= x y) 1 0))))))
(do-instructions (inst iblock)
(let ((folder (cdr (assoc inst folders :test #'typep))))
(when (and folder (every #'ir-constant-p (inputs inst)))
(let* ((output (change-class (output inst) 'ir-constant
:users (users (output inst))))
(operands (mapcar #'ir-constant-value (inputs inst))))
(setf (output inst) nil
(inputs inst) nil)
(insert-instruction-above
(make-instance 'ir-getconst
:input (apply folder operands)
:output output)
inst)
(delete-instruction inst)))))))
(defun optim-commutative-constant-folding (iblock)
"Attempts to replace operations with compile-time computed constants."
(do-instructions (inst iblock)