| /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- |
| * vim: set ts=8 sts=4 et sw=4 tw=99: |
| * This Source Code Form is subject to the terms of the Mozilla Public |
| * License, v. 2.0. If a copy of the MPL was not distributed with this |
| * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| |
| #ifndef frontend_SourceNotes_h |
| #define frontend_SourceNotes_h |
| |
| #include "jsprvtd.h" |
| |
| namespace js { |
| |
| /* |
| * Source notes generated along with bytecode for decompiling and debugging. |
| * A source note is a uint8_t with 5 bits of type and 3 of offset from the pc |
| * of the previous note. If 3 bits of offset aren't enough, extended delta |
| * notes (SRC_XDELTA) consisting of 2 set high order bits followed by 6 offset |
| * bits are emitted before the next note. Some notes have operand offsets |
| * encoded immediately after them, in note bytes or byte-triples. |
| * |
| * Source Note Extended Delta |
| * +7-6-5-4-3+2-1-0+ +7-6-5+4-3-2-1-0+ |
| * |note-type|delta| |1 1| ext-delta | |
| * +---------+-----+ +---+-----------+ |
| * |
| * At most one "gettable" note (i.e., a note of type other than SRC_NEWLINE, |
| * SRC_COLSPAN, SRC_SETLINE, and SRC_XDELTA) applies to a given bytecode. |
| * |
| * NB: the js_SrcNoteSpec array in BytecodeEmitter.cpp is indexed by this |
| * enum, so its initializers need to match the order here. |
| * |
| * Don't forget to update XDR_BYTECODE_VERSION in vm/Xdr.h for all such |
| * incompatible source note or other bytecode changes. |
| */ |
| enum SrcNoteType { |
| SRC_NULL = 0, /* terminates a note vector */ |
| |
| SRC_IF = 1, /* JSOP_IFEQ bytecode is from an if-then */ |
| SRC_IF_ELSE = 2, /* JSOP_IFEQ bytecode is from an if-then-else */ |
| SRC_COND = 3, /* JSOP_IFEQ is from conditional ?: operator */ |
| |
| SRC_FOR = 4, /* JSOP_NOP or JSOP_POP in for(;;) loop head */ |
| |
| SRC_WHILE = 5, /* JSOP_GOTO to for or while loop condition |
| from before loop, else JSOP_NOP at top of |
| do-while loop */ |
| SRC_FOR_IN = 6, /* JSOP_GOTO to for-in loop condition from |
| before loop */ |
| SRC_CONTINUE = 7, /* JSOP_GOTO is a continue */ |
| SRC_BREAK = 8, /* JSOP_GOTO is a break */ |
| SRC_BREAK2LABEL = 9, /* JSOP_GOTO for 'break label' */ |
| SRC_SWITCHBREAK = 10, /* JSOP_GOTO is a break in a switch */ |
| |
| SRC_TABLESWITCH = 11, /* JSOP_TABLESWITCH, offset points to end of |
| switch */ |
| SRC_CONDSWITCH = 12, /* JSOP_CONDSWITCH, 1st offset points to end of |
| switch, 2nd points to first JSOP_CASE */ |
| |
| SRC_NEXTCASE = 13, /* distance forward from one CASE in a |
| CONDSWITCH to the next */ |
| |
| SRC_ASSIGNOP = 14, /* += or another assign-op follows */ |
| |
| SRC_HIDDEN = 15, /* opcode shouldn't be decompiled */ |
| |
| SRC_CATCH = 16, /* catch block has guard */ |
| |
| /* All notes below here are "gettable". See SN_IS_GETTABLE below. */ |
| SRC_LAST_GETTABLE = SRC_CATCH, |
| |
| SRC_COLSPAN = 17, /* number of columns this opcode spans */ |
| SRC_NEWLINE = 18, /* bytecode follows a source newline */ |
| SRC_SETLINE = 19, /* a file-absolute source line number note */ |
| |
| SRC_UNUSED20 = 20, |
| SRC_UNUSED21 = 21, |
| SRC_UNUSED22 = 22, |
| SRC_UNUSED23 = 23, |
| |
| SRC_XDELTA = 24 /* 24-31 are for extended delta notes */ |
| }; |
| |
| } // namespace js |
| |
| #define SN_TYPE_BITS 5 |
| #define SN_DELTA_BITS 3 |
| #define SN_XDELTA_BITS 6 |
| #define SN_TYPE_MASK (JS_BITMASK(SN_TYPE_BITS) << SN_DELTA_BITS) |
| #define SN_DELTA_MASK ((ptrdiff_t)JS_BITMASK(SN_DELTA_BITS)) |
| #define SN_XDELTA_MASK ((ptrdiff_t)JS_BITMASK(SN_XDELTA_BITS)) |
| |
| #define SN_MAKE_NOTE(sn,t,d) (*(sn) = (jssrcnote) \ |
| (((t) << SN_DELTA_BITS) \ |
| | ((d) & SN_DELTA_MASK))) |
| #define SN_MAKE_XDELTA(sn,d) (*(sn) = (jssrcnote) \ |
| ((SRC_XDELTA << SN_DELTA_BITS) \ |
| | ((d) & SN_XDELTA_MASK))) |
| |
| #define SN_IS_XDELTA(sn) ((*(sn) >> SN_DELTA_BITS) >= SRC_XDELTA) |
| #define SN_TYPE(sn) ((js::SrcNoteType)(SN_IS_XDELTA(sn) \ |
| ? SRC_XDELTA \ |
| : *(sn) >> SN_DELTA_BITS)) |
| #define SN_SET_TYPE(sn,type) SN_MAKE_NOTE(sn, type, SN_DELTA(sn)) |
| #define SN_IS_GETTABLE(sn) (SN_TYPE(sn) <= SRC_LAST_GETTABLE) |
| |
| #define SN_DELTA(sn) ((ptrdiff_t)(SN_IS_XDELTA(sn) \ |
| ? *(sn) & SN_XDELTA_MASK \ |
| : *(sn) & SN_DELTA_MASK)) |
| #define SN_SET_DELTA(sn,delta) (SN_IS_XDELTA(sn) \ |
| ? SN_MAKE_XDELTA(sn, delta) \ |
| : SN_MAKE_NOTE(sn, SN_TYPE(sn), delta)) |
| |
| #define SN_DELTA_LIMIT ((ptrdiff_t)JS_BIT(SN_DELTA_BITS)) |
| #define SN_XDELTA_LIMIT ((ptrdiff_t)JS_BIT(SN_XDELTA_BITS)) |
| |
| /* |
| * Offset fields follow certain notes and are frequency-encoded: an offset in |
| * [0,0x7f] consumes one byte, an offset in [0x80,0x7fffff] takes three, and |
| * the high bit of the first byte is set. |
| */ |
| #define SN_3BYTE_OFFSET_FLAG 0x80 |
| #define SN_3BYTE_OFFSET_MASK 0x7f |
| |
| /* |
| * Negative SRC_COLSPAN offsets are rare, but can arise with for(;;) loops and |
| * other constructs that generate code in non-source order. They can also arise |
| * due to failure to update pn->pn_pos.end to be the last child's end -- such |
| * failures are bugs to fix. |
| * |
| * Source note offsets in general must be non-negative and less than 0x800000, |
| * per the above SN_3BYTE_* definitions. To encode negative colspans, we bias |
| * them by the offset domain size and restrict non-negative colspans to less |
| * than half this domain. |
| */ |
| #define SN_COLSPAN_DOMAIN ptrdiff_t(SN_3BYTE_OFFSET_FLAG << 16) |
| |
| #define SN_MAX_OFFSET ((size_t)((ptrdiff_t)SN_3BYTE_OFFSET_FLAG << 16) - 1) |
| |
| #define SN_LENGTH(sn) ((js_SrcNoteSpec[SN_TYPE(sn)].arity == 0) ? 1 \ |
| : js_SrcNoteLength(sn)) |
| #define SN_NEXT(sn) ((sn) + SN_LENGTH(sn)) |
| |
| /* A source note array is terminated by an all-zero element. */ |
| #define SN_MAKE_TERMINATOR(sn) (*(sn) = SRC_NULL) |
| #define SN_IS_TERMINATOR(sn) (*(sn) == SRC_NULL) |
| |
| struct JSSrcNoteSpec { |
| const char *name; /* name for disassembly/debugging output */ |
| int8_t arity; /* number of offset operands */ |
| }; |
| |
| extern JS_FRIEND_DATA(const JSSrcNoteSpec) js_SrcNoteSpec[]; |
| extern JS_FRIEND_API(unsigned) js_SrcNoteLength(jssrcnote *sn); |
| |
| /* |
| * Get and set the offset operand identified by which (0 for the first, etc.). |
| */ |
| extern JS_FRIEND_API(ptrdiff_t) |
| js_GetSrcNoteOffset(jssrcnote *sn, unsigned which); |
| |
| #endif /* frontend_SourceNotes_h */ |