Raymond Toy pushed to branch master at cmucl / cmucl

Commits: 0d6882c7 by Raymond Toy at 2024-03-10T20:12:37+00:00 Fix #274: 1d999999 hangs cmucl

- - - - - 34f33e19 by Raymond Toy at 2024-03-10T20:12:38+00:00 Merge branch 'issue-274-make-float-of-huge-numbers' into 'master'

Fix #274: 1d999999 hangs cmucl

Closes #274

See merge request cmucl/cmucl!189 - - - - -

3 changed files:

- src/code/reader.lisp - src/i18n/locale/cmucl.pot - tests/float.lisp

Changes:

===================================== src/code/reader.lisp ===================================== @@ -1785,7 +1785,7 @@ the end of the stream." ;; Is there an exponent letter? (cond ((eofp char) ;; If not, we've read the whole number. - (let ((num (make-float-aux number divisor + (let ((num (make-float-aux 0 number divisor *read-default-float-format* stream))) (return-from make-float (if negative-fraction (- num) num)))) @@ -1815,7 +1815,7 @@ the end of the stream." #+double-double (#\W 'kernel:double-double-float))) num) - (setq num (make-float-aux (* (expt 10 exponent) number) divisor + (setq num (make-float-aux exponent number divisor float-format stream))

(return-from make-float (if negative-fraction @@ -1823,10 +1823,55 @@ the end of the stream." num)))) (t (error _"Internal error in floating point reader.")))))

-(defun make-float-aux (number divisor float-format stream) +(defun make-float-aux (exponent number divisor float-format stream) + ;; Computes x = number*10^exponent/divisor. + ;; + ;; First check to see if x can possibly fit into a float of the + ;; given format. So compute log2(x) to get an approximate value of + ;; the base 2 exponent of x. If it's too large or too small, we can + ;; throw an error immediately. We don't need to be super accurate + ;; with the limits. The rest of the code will handle it correctly, + ;; even if we're too small or too large. + (unless (zerop number) + (flet ((fast-log2 (n) + ;; For an integer, the integer-length is close enough to + ;; the log2 of the number. + (integer-length n))) + ;; log2(x) = log(number*10^exponent/divisor) + ;; = exponent*log2(10) + log2(number)-log2(divisor) + (let ((log2-num (+ (* exponent #.(kernel::log2 10d0)) + (fast-log2 number) + (- (fast-log2 divisor))))) + (multiple-value-bind (log2-low log2-high) + (ecase float-format + ((short-float single-float) + ;; Single-float exponents range is -149 to 127, but we + ;; don't need to be super-accurate since we're + ;; multiplying the values by 2. + (values (* 2 (- vm:single-float-normal-exponent-min + vm:single-float-bias + vm:single-float-digits)) + (* 2 (- vm:single-float-normal-exponent-max + vm:single-float-bias)))) + ((double-float long-float + #+double-double kernel:double-double-float) + (values (* 2 (- vm:double-float-normal-exponent-min + vm:double-float-bias + vm:double-float-digits)) + (* 2 (- vm:double-float-normal-exponent-max + vm:double-float-bias))))) + ;; Double-float exponent range is -1074 to -1023 + (unless (< log2-low log2-num log2-high) + ;; The number is definitely too large or too small to fit. + ;; Signal an error. + (%reader-error stream _"Number not representable as a ~S: ~S" + float-format (read-buffer-to-string))))))) + + ;; Otherwise the number might fit, so we carefully compute the result (handler-case (with-float-traps-masked (:underflow) - (let* ((ratio (/ number divisor)) + (let* ((ratio (/ (* (expt 10 exponent) number) + divisor)) (result (coerce ratio float-format))) (when (and (zerop result) (not (zerop number))) ;; The number we've read is so small that it gets @@ -1850,7 +1895,7 @@ the end of the stream." result)) (error () (%reader-error stream _"Number not representable as a ~S: ~S" - float-format (/ number divisor))))) + float-format (read-buffer-to-string)))))

(defun make-ratio (stream)

===================================== src/i18n/locale/cmucl.pot ===================================== @@ -8728,11 +8728,11 @@ msgid "Internal error in floating point reader." msgstr ""

#: src/code/reader.lisp -msgid "Underflow" +msgid "Number not representable as a ~S: ~S" msgstr ""

#: src/code/reader.lisp -msgid "Number not representable as a ~S: ~S" +msgid "Underflow" msgstr ""

#: src/code/reader.lisp

===================================== tests/float.lisp ===================================== @@ -182,3 +182,33 @@ (assert-equal least-positive-double-float (kernel::float-ratio-float (* 988/100 expo) 'double-float)))))

+(define-test reader-error.small-single-floats + (:tag :issues) + ;; Test a number less than half of least-positive-single-float, + ;; something a bit smaller, hen then something really small that + ;; used to appear to hang cmucl because it was trying to compute the + ;; a rational with a huge number of digits. + (dolist (num '("1e-46" "1e-80" "1e-999999999")) + (assert-error 'reader-error (read-from-string num) + num))) + +(define-test reader-error.small-double-floats + (:tag :issues) + ;; Like reader-error.small-single-floats but for doubles + (dolist (num '("1d-324" "1d-600" "1d-999999999")) + (assert-error 'reader-error (read-from-string num) + num))) + +(define-test reader-error.big-single-floats + (:tag :issues) + ;; Signal error for a number just a bit larger than + ;; most-positive-single-float. And a really big single-float. + (assert-error 'reader-error (read-from-string "3.5e38")) + (assert-error 'reader-error (read-from-string "1e999999999"))) + +(define-test reader-error.big-double-floats + (:tag :issues) + ;; Signal error for a number just a bit larger than + ;; most-positive-double-float. And a really big single-float. + (assert-error 'reader-error (read-from-string "1.8d308")) + (assert-error 'reader-error (read-from-string "1d999999999")))

View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/compare/8faafb3259fc5f220c887c8...