Raymond Toy pushed to branch issue-168-no-negated-forms-for-jmp at cmucl / cmucl

Commits: 96310401 by Raymond Toy at 2023-02-26T16:19:45-08:00 Add some comments on what the different jmp conditions mean

I always forget the difference between, say, `:be` and `:le`. The former is for unsigned comparisons and the later for signed.

So add some short comments on what the conditions really mean.

- - - - -

1 changed file:

- src/compiler/x86/insts.lisp

Changes:

===================================== src/compiler/x86/insts.lisp ===================================== @@ -259,21 +259,38 @@ ;; the first one is the one that is preferred when printing the ;; condition code out. (defconstant conditions - '((:o . 0) + '( + ;; OF = 1 + (:o . 0) + ;; OF = 0 (:no . 1) + ;; Unsigned <; CF = 1 (:b . 2) (:nae . 2) (:c . 2) + ;; Unsigned >=; CF = 0 (:ae . 3) (:nb . 3) (:nc . 3) + ;; Equal; ZF = 1 (:e . 4) (:eq . 4) (:z . 4) + ;; Not equal; ZF = 0 (:ne . 5) (:nz . 5) + ;; Unsigned <=; CF = 1 or ZF = 1 (:be . 6) (:na . 6) + ;; Unsigned >; CF = 1 and ZF = 0 (:a . 7) (:nbe . 7) + ;; SF = 1 (:s . 8) + ;; SF = 0 (:ns . 9) + ;; Parity even (:p . 10) (:pe . 10) + ;; Parity odd (:np . 11) (:po . 11) + ;; Signed <; SF /= OF (:l . 12) (:nge . 12) + ;; Signed >=; SF = OF (:ge . 13) (:nl . 13) + ;; Signed <=; ZF = 1 or SF /= OF (:le . 14) (:ng . 14) + ;; Signed >; ZF =0 and SF = OF (:g . 15) (:nle . 15)))

(defun conditional-opcode (condition)

View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/commit/963104015b369a7c835bc703...