From: Mattias Engdegård Date: Fri, 24 Jun 2022 09:48:42 +0000 (+0200) Subject: Bytecode opcode comments update X-Git-Tag: emacs-29.0.90~1447^2~1495 X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=253a4a2c689d757cb798cfb9f51b2110283d7146;p=emacs.git Bytecode opcode comments update This is a cosmetic change only; there is no change in behaviour. * lisp/emacs-lisp/bytecomp.el: * src/bytecode.c (BYTE_CODES, exec_byte_code): Update and/or remove incorrect, outdated or useless comments. Clarify. Reorder where appropriate. Rename Bsave_current_buffer to Bsave_current_buffer_OBSOLETE and Bsave_current_buffer_1 to Bsave_current_buffer, reflecting the state since 1996. --- diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el index a8c68f81531..bd3db85c148 100644 --- a/lisp/emacs-lisp/bytecomp.el +++ b/lisp/emacs-lisp/bytecomp.el @@ -681,10 +681,13 @@ Each element is (INDEX . VALUE)") (put 'byte-stack+-info 'tmp-compile-time-value nil))) -;; These opcodes are special in that they pack their argument into the -;; opcode word. -;; +;; The following opcodes (1-47) use the 3 lowest bits for an immediate +;; argument. + (byte-defop 0 1 byte-stack-ref "for stack reference") +;; Code 0 is actually unused but reserved as invalid code for detecting +;; corrupted bytecode. Codes 1-7 are stack-ref. + (byte-defop 8 1 byte-varref "for variable reference") (byte-defop 16 -1 byte-varset "for setting a variable") (byte-defop 24 -1 byte-varbind "for binding a variable") @@ -692,11 +695,9 @@ Each element is (INDEX . VALUE)") (byte-defop 40 0 byte-unbind "for unbinding special bindings") ;; codes 8-47 are consumed by the preceding opcodes -;; New (in Emacs-24.4) bytecodes for more efficient handling of non-local exits -;; (especially useful in lexical-binding code). (byte-defop 48 0 byte-pophandler) -(byte-defop 50 -1 byte-pushcatch) (byte-defop 49 -1 byte-pushconditioncase) +(byte-defop 50 -1 byte-pushcatch) ;; unused: 51-55 @@ -719,9 +720,9 @@ Each element is (INDEX . VALUE)") (byte-defop 72 -1 byte-aref) (byte-defop 73 -2 byte-aset) (byte-defop 74 0 byte-symbol-value) -(byte-defop 75 0 byte-symbol-function) ; this was commented out +(byte-defop 75 0 byte-symbol-function) (byte-defop 76 -1 byte-set) -(byte-defop 77 -1 byte-fset) ; this was commented out +(byte-defop 77 -1 byte-fset) (byte-defop 78 -1 byte-get) (byte-defop 79 -2 byte-substring) (byte-defop 80 -1 byte-concat2) @@ -739,8 +740,9 @@ Each element is (INDEX . VALUE)") (byte-defop 92 -1 byte-plus) (byte-defop 93 -1 byte-max) (byte-defop 94 -1 byte-min) -(byte-defop 95 -1 byte-mult) ; v19 only +(byte-defop 95 -1 byte-mult) (byte-defop 96 1 byte-point) +(byte-defop 97 0 byte-save-current-buffer-OBSOLETE) ; unused since v20 (byte-defop 98 0 byte-goto-char) (byte-defop 99 0 byte-insert) (byte-defop 100 1 byte-point-max) @@ -762,7 +764,6 @@ Each element is (INDEX . VALUE)") (byte-defop 115 0 byte-set-mark-OBSOLETE) (byte-defop 116 1 byte-interactive-p-OBSOLETE) -;; These ops are new to v19 (byte-defop 117 0 byte-forward-char) (byte-defop 118 0 byte-forward-word) (byte-defop 119 -1 byte-skip-chars-forward) @@ -819,7 +820,6 @@ the unwind-action") ;; unused: 146 -;; these ops are new to v19 (byte-defop 147 -2 byte-set-marker) (byte-defop 148 0 byte-match-beginning) (byte-defop 149 0 byte-match-end) @@ -866,10 +866,11 @@ the unwind-action") "to take a hash table and a value from the stack, and jump to the address the value maps to, if any.") -;; unused: 182-191 +;; unused: 184-191 (byte-defop 192 1 byte-constant "for reference to a constant") -;; codes 193-255 are consumed by byte-constant. +;; Codes 193-255 are consumed by `byte-constant', which uses the 6 +;; lowest bits for an immediate argument. (defconst byte-constant-limit 64 "Exclusive maximum index usable in the `byte-constant' opcode.") diff --git a/src/bytecode.c b/src/bytecode.c index fa068e1ec6b..d75767bb0c5 100644 --- a/src/bytecode.c +++ b/src/bytecode.c @@ -176,8 +176,8 @@ DEFINE (Bmin, 0136) \ DEFINE (Bmult, 0137) \ \ DEFINE (Bpoint, 0140) \ -/* Was Bmark in v17. */ \ -DEFINE (Bsave_current_buffer, 0141) /* Obsolete. */ \ +/* 0141 was Bmark in v17, Bsave_current_buffer in 18-19. */ \ +DEFINE (Bsave_current_buffer_OBSOLETE, 0141) /* Obsolete since 20. */ \ DEFINE (Bgoto_char, 0142) \ DEFINE (Binsert, 0143) \ DEFINE (Bpoint_max, 0144) \ @@ -194,7 +194,7 @@ DEFINE (Bbolp, 0156) \ DEFINE (Bbobp, 0157) \ DEFINE (Bcurrent_buffer, 0160) \ DEFINE (Bset_buffer, 0161) \ -DEFINE (Bsave_current_buffer_1, 0162) /* Replacing Bsave_current_buffer. */ \ +DEFINE (Bsave_current_buffer, 0162) \ /* 0163 was Bset_mark in v17. */ \ DEFINE (Binteractive_p, 0164) /* Obsolete since Emacs-24.1. */ \ \ @@ -924,8 +924,8 @@ exec_byte_code (Lisp_Object fun, ptrdiff_t args_template, record_unwind_protect_excursion (); NEXT; - CASE (Bsave_current_buffer): /* Obsolete since ??. */ - CASE (Bsave_current_buffer_1): + CASE (Bsave_current_buffer_OBSOLETE): /* Obsolete since 20. */ + CASE (Bsave_current_buffer): record_unwind_current_buffer (); NEXT; @@ -1678,6 +1678,12 @@ exec_byte_code (Lisp_Object fun, ptrdiff_t args_template, /* TODO: Perhaps introduce another byte-code for switch when the number of cases is less, which uses a simple vector for linear search as the jump table. */ + + /* TODO: Instead of pushing the table in a separate + Bconstant op, use an immediate argument (maybe separate + switch opcodes for 1-byte and 2-byte constant indices). + This would also get rid of some hacks that assume each + Bswitch to be preceded by a Bconstant. */ Lisp_Object jmp_table = POP; if (BYTE_CODE_SAFE && !HASH_TABLE_P (jmp_table)) emacs_abort ();