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https://repo.dactyloidae.xyz/Dactyloidae/UXP.git
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f79ee2fd83
This is accomplished in the following ways. LazyScripts and JSScripts now have 4 offsets: - Source begin and end for the actual source. This is used for lazy parsing. - toString begin and end for toString. Some kinds of functions, like async, only have a different begin offset. Class constructors have different offsets for both begin and end. For syntactically present (i.e. non-default) constructors, the class source span is remembered directly on the LazyScript or JSScript. The toString implementation then splices out the substring directly. For default constructors, a new SRC_CLASS SrcNote type is added. It's binary and has as its arguments the begin and end offsets of the class expression or statement. MakeDefaultConstructor reads the note and overrides the cloned self-hosted function's source object. This is probably the least intrusive way to accomplish this.
208 lines
9.7 KiB
C++
208 lines
9.7 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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* vim: set ts=8 sts=4 et sw=4 tw=99:
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef frontend_SourceNotes_h
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#define frontend_SourceNotes_h
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#include <stdint.h>
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#include "jstypes.h"
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typedef uint8_t jssrcnote;
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namespace js {
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/*
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* Source notes generated along with bytecode for decompiling and debugging.
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* A source note is a uint8_t with 5 bits of type and 3 of offset from the pc
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* of the previous note. If 3 bits of offset aren't enough, extended delta
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* notes (SRC_XDELTA) consisting of 2 set high order bits followed by 6 offset
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* bits are emitted before the next note. Some notes have operand offsets
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* encoded immediately after them, in note bytes or byte-triples.
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*
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* Source Note Extended Delta
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* +7-6-5-4-3+2-1-0+ +7-6-5+4-3-2-1-0+
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* |note-type|delta| |1 1| ext-delta |
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* +---------+-----+ +---+-----------+
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*
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* At most one "gettable" note (i.e., a note of type other than SRC_NEWLINE,
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* SRC_COLSPAN, SRC_SETLINE, and SRC_XDELTA) applies to a given bytecode.
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*
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* NB: the js_SrcNoteSpec array in BytecodeEmitter.cpp is indexed by this
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* enum, so its initializers need to match the order here.
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*/
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#define FOR_EACH_SRC_NOTE_TYPE(M) \
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M(SRC_NULL, "null", 0) /* Terminates a note vector. */ \
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M(SRC_IF, "if", 0) /* JSOP_IFEQ bytecode is from an if-then. */ \
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M(SRC_IF_ELSE, "if-else", 1) /* JSOP_IFEQ bytecode is from an if-then-else. */ \
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M(SRC_COND, "cond", 1) /* JSOP_IFEQ is from conditional ?: operator. */ \
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M(SRC_FOR, "for", 3) /* JSOP_NOP or JSOP_POP in for(;;) loop head. */ \
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M(SRC_WHILE, "while", 1) /* JSOP_GOTO to for or while loop condition from before \
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loop, else JSOP_NOP at top of do-while loop. */ \
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M(SRC_FOR_IN, "for-in", 1) /* JSOP_GOTO to for-in loop condition from before \
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loop. */ \
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M(SRC_FOR_OF, "for-of", 1) /* JSOP_GOTO to for-of loop condition from before \
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loop. */ \
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M(SRC_CONTINUE, "continue", 0) /* JSOP_GOTO is a continue. */ \
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M(SRC_BREAK, "break", 0) /* JSOP_GOTO is a break. */ \
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M(SRC_BREAK2LABEL, "break2label", 0) /* JSOP_GOTO for 'break label'. */ \
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M(SRC_SWITCHBREAK, "switchbreak", 0) /* JSOP_GOTO is a break in a switch. */ \
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M(SRC_TABLESWITCH, "tableswitch", 1) /* JSOP_TABLESWITCH; offset points to end of switch. */ \
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M(SRC_CONDSWITCH, "condswitch", 2) /* JSOP_CONDSWITCH; 1st offset points to end of switch, \
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2nd points to first JSOP_CASE. */ \
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M(SRC_NEXTCASE, "nextcase", 1) /* Distance forward from one CASE in a CONDSWITCH to \
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the next. */ \
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M(SRC_ASSIGNOP, "assignop", 0) /* += or another assign-op follows. */ \
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M(SRC_CLASS_SPAN, "class", 2) /* The starting and ending offsets for the class, used \
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for toString correctness for default ctors. */ \
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M(SRC_TRY, "try", 1) /* JSOP_TRY, offset points to goto at the end of the \
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try block. */ \
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/* All notes above here are "gettable". See SN_IS_GETTABLE below. */ \
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M(SRC_COLSPAN, "colspan", 1) /* Number of columns this opcode spans. */ \
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M(SRC_NEWLINE, "newline", 0) /* Bytecode follows a source newline. */ \
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M(SRC_SETLINE, "setline", 1) /* A file-absolute source line number note. */ \
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M(SRC_UNUSED21, "unused21", 0) /* Unused. */ \
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M(SRC_UNUSED22, "unused22", 0) /* Unused. */ \
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M(SRC_UNUSED23, "unused23", 0) /* Unused. */ \
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M(SRC_XDELTA, "xdelta", 0) /* 24-31 are for extended delta notes. */
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enum SrcNoteType {
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#define DEFINE_SRC_NOTE_TYPE(sym, name, arity) sym,
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FOR_EACH_SRC_NOTE_TYPE(DEFINE_SRC_NOTE_TYPE)
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#undef DEFINE_SRC_NOTE_TYPE
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SRC_LAST,
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SRC_LAST_GETTABLE = SRC_TRY
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};
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static_assert(SRC_XDELTA == 24, "SRC_XDELTA should be 24");
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/* A source note array is terminated by an all-zero element. */
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inline void
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SN_MAKE_TERMINATOR(jssrcnote* sn)
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{
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*sn = SRC_NULL;
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}
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inline bool
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SN_IS_TERMINATOR(jssrcnote* sn)
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{
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return *sn == SRC_NULL;
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}
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} // namespace js
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#define SN_TYPE_BITS 5
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#define SN_DELTA_BITS 3
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#define SN_XDELTA_BITS 6
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#define SN_TYPE_MASK (JS_BITMASK(SN_TYPE_BITS) << SN_DELTA_BITS)
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#define SN_DELTA_MASK ((ptrdiff_t)JS_BITMASK(SN_DELTA_BITS))
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#define SN_XDELTA_MASK ((ptrdiff_t)JS_BITMASK(SN_XDELTA_BITS))
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#define SN_MAKE_NOTE(sn,t,d) (*(sn) = (jssrcnote) \
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(((t) << SN_DELTA_BITS) \
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| ((d) & SN_DELTA_MASK)))
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#define SN_MAKE_XDELTA(sn,d) (*(sn) = (jssrcnote) \
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((SRC_XDELTA << SN_DELTA_BITS) \
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| ((d) & SN_XDELTA_MASK)))
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#define SN_IS_XDELTA(sn) ((*(sn) >> SN_DELTA_BITS) >= SRC_XDELTA)
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#define SN_TYPE(sn) ((js::SrcNoteType)(SN_IS_XDELTA(sn) \
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? SRC_XDELTA \
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: *(sn) >> SN_DELTA_BITS))
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#define SN_SET_TYPE(sn,type) SN_MAKE_NOTE(sn, type, SN_DELTA(sn))
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#define SN_IS_GETTABLE(sn) (SN_TYPE(sn) <= SRC_LAST_GETTABLE)
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#define SN_DELTA(sn) ((ptrdiff_t)(SN_IS_XDELTA(sn) \
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? *(sn) & SN_XDELTA_MASK \
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: *(sn) & SN_DELTA_MASK))
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#define SN_SET_DELTA(sn,delta) (SN_IS_XDELTA(sn) \
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? SN_MAKE_XDELTA(sn, delta) \
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: SN_MAKE_NOTE(sn, SN_TYPE(sn), delta))
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#define SN_DELTA_LIMIT ((ptrdiff_t)JS_BIT(SN_DELTA_BITS))
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#define SN_XDELTA_LIMIT ((ptrdiff_t)JS_BIT(SN_XDELTA_BITS))
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/*
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* Offset fields follow certain notes and are frequency-encoded: an offset in
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* [0,0x7f] consumes one byte, an offset in [0x80,0x7fffffff] takes four, and
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* the high bit of the first byte is set.
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*/
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#define SN_4BYTE_OFFSET_FLAG 0x80
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#define SN_4BYTE_OFFSET_MASK 0x7f
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#define SN_OFFSET_BITS 31
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#define SN_MAX_OFFSET (((size_t) 1 << SN_OFFSET_BITS) - 1)
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inline bool
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SN_REPRESENTABLE_OFFSET(ptrdiff_t offset)
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{
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return 0 <= offset && size_t(offset) <= SN_MAX_OFFSET;
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}
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/*
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* SRC_COLSPAN values represent changes to the column number. Colspans are
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* signed: negative changes arise in describing constructs like for(;;) loops,
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* that generate code in non-source order. (Negative colspans also have a
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* history of indicating bugs in updating ParseNodes' source locations.)
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*
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* We store colspans using the same variable-length encoding as offsets,
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* described above. However, unlike offsets, colspans are signed, so we truncate
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* colspans (SN_COLSPAN_TO_OFFSET) for storage as offsets, and sign-extend
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* offsets into colspans when we read them (SN_OFFSET_TO_COLSPAN).
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*/
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#define SN_COLSPAN_SIGN_BIT (1 << (SN_OFFSET_BITS - 1))
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#define SN_MIN_COLSPAN (-SN_COLSPAN_SIGN_BIT)
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#define SN_MAX_COLSPAN (SN_COLSPAN_SIGN_BIT - 1)
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inline bool
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SN_REPRESENTABLE_COLSPAN(ptrdiff_t colspan)
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{
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return SN_MIN_COLSPAN <= colspan && colspan <= SN_MAX_COLSPAN;
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}
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inline ptrdiff_t
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SN_OFFSET_TO_COLSPAN(ptrdiff_t offset) {
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// There should be no bits set outside the field we're going to sign-extend.
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MOZ_ASSERT(!(offset & ~((1U << SN_OFFSET_BITS) - 1)));
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// Sign-extend the least significant SN_OFFSET_BITS bits.
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return (offset ^ SN_COLSPAN_SIGN_BIT) - SN_COLSPAN_SIGN_BIT;
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}
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inline ptrdiff_t
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SN_COLSPAN_TO_OFFSET(ptrdiff_t colspan) {
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// Truncate the two's complement colspan, for storage as an offset.
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ptrdiff_t offset = colspan & ((1U << SN_OFFSET_BITS) - 1);
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// When we read this back, we'd better get the value we stored.
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MOZ_ASSERT(SN_OFFSET_TO_COLSPAN(offset) == colspan);
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return offset;
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}
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#define SN_LENGTH(sn) ((js_SrcNoteSpec[SN_TYPE(sn)].arity == 0) ? 1 \
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: js::SrcNoteLength(sn))
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#define SN_NEXT(sn) ((sn) + SN_LENGTH(sn))
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struct JSSrcNoteSpec {
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const char* name; /* name for disassembly/debugging output */
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int8_t arity; /* number of offset operands */
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};
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extern JS_FRIEND_DATA(const JSSrcNoteSpec) js_SrcNoteSpec[];
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namespace js {
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extern JS_FRIEND_API(unsigned)
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SrcNoteLength(jssrcnote* sn);
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/*
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* Get and set the offset operand identified by which (0 for the first, etc.).
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*/
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extern JS_FRIEND_API(ptrdiff_t)
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GetSrcNoteOffset(jssrcnote* sn, unsigned which);
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} // namespace js
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#endif /* frontend_SourceNotes_h */
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