From 8285c78283f922e5b5569ce5c28fb25074db0af3 Mon Sep 17 00:00:00 2001 From: Benoit Giannangeli Date: Mon, 27 Feb 2017 21:49:27 +0100 Subject: parsing --- src/lcode.js | 223 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 223 insertions(+) create mode 100644 src/lcode.js (limited to 'src/lcode.js') diff --git a/src/lcode.js b/src/lcode.js new file mode 100644 index 0000000..695c7dc --- /dev/null +++ b/src/lcode.js @@ -0,0 +1,223 @@ +/* jshint esversion: 6 */ +"use strict"; + +const assert = require('assert'); + +const lopcode = require('./lopcode.js'); +const llex = require('./llex.js'); +const lcode = require('./lcode.js'); +const OpCodesI = lopcode.OpCodesI; + +/* +** Marks the end of a patch list. It is an invalid value both as an absolute +** address, and as a list link (would link an element to itself). +*/ +const NO_JUMP = -1; + +/* +** Gets the destination address of a jump instruction. Used to traverse +** a list of jumps. +*/ +const getjump = function(fs, pc) { + let offset = fs.f.code[pc].sBx; + if (offset === NO_JUMP) /* point to itself represents end of list */ + return NO_JUMP; /* end of list */ + else + return pc + 1 + offset; /* turn offset into absolute position */ +}; + +/* +** Fix jump instruction at position 'pc' to jump to 'dest'. +** (Jump addresses are relative in Lua) +*/ +const fixjump = function(fs, pc, dest) { + let jmp = fs.f.code[pc]; + let offset = dest - (pc + 1); + assert(dest !== NO_JUMP); + if (Math.abs(offset) > lopcode.MAXARG_sBx) + llex.luaX_syntaxerror(fs.ls, "control structure too long"); + lopcode.SETARG_sBx(jmp, offset); +}; + +/* +** Concatenate jump-list 'l2' into jump-list 'l1' +*/ +const luaK_concat = function(fs, l1, l2) { + if (l2 === NO_JUMP) return; /* nothing to concatenate? */ + else if (l1 === NO_JUMP) /* no original list? */ + l1[0] = l2; + else { + let list = l1[0]; + let next = getjump(fs, list); + while (next !== NO_JUMP) { /* find last element */ + list = next; + next = getjump(fs, list); + } + fixjump(fs, list, l2); + } +}; + +/* +** Create a jump instruction and return its position, so its destination +** can be fixed later (with 'fixjump'). If there are jumps to +** this position (kept in 'jpc'), link them all together so that +** 'patchlistaux' will fix all them directly to the final destination. +*/ +const luaK_jump = function (fs) { + let jpc = fs.jpc; /* save list of jumps to here */ + fs.jpc = NO_JUMP; /* no more jumps to here */ + let j = luaK_codeAsBx(fs, OpCodesI.OP_JMP, 0, NO_JUMP); + luaK_concat(fs, j, jpc); /* keep them on hold */ + return j; +}; + +/* +** Code a 'return' instruction +*/ +const luaK_ret = function(fs, first, nret) { + luaK_codeABC(fs, OpCodesI.OP_RETURN, first, nret + 1, 0); +}; + +/* +** returns current 'pc' and marks it as a jump target (to avoid wrong +** optimizations with consecutive instructions not in the same basic block). +*/ +const luaK_getlabel = function(fs) { + fs.lasttarget = fs.pc; + return fs.pc; +}; + +/* +** Returns the position of the instruction "controlling" a given +** jump (that is, its condition), or the jump itself if it is +** unconditional. +*/ +const getjumpcontrol = function(fs, pc) { + if (pc >= 1 && lopcode.testTMode(fs.f.code[pc - 1].opcode)) + return fs.f.code[pc - 1]; + else + return fs.f.code[pc]; +}; + +/* +** Patch destination register for a TESTSET instruction. +** If instruction in position 'node' is not a TESTSET, return 0 ("fails"). +** Otherwise, if 'reg' is not 'NO_REG', set it as the destination +** register. Otherwise, change instruction to a simple 'TEST' (produces +** no register value) +*/ +const patchtestreg = function(fs, node, reg) { + let i = getjumpcontrol(fs, node); + if (i.opcode !== OpCodesI.OP_TESTSET) + return false; /* cannot patch other instructions */ + if (reg !== lopcode.NO_REG && reg !== i.B) + lopcode.SETARG_A(i, reg); + else { + /* no register to put value or register already has the value; + change instruction to simple test */ + i = lopcode.CREATE_ABC(OpCodesI.OP_TEST, i.B, 0, i.C); + } + return true; +}; + +/* +** Traverse a list of tests, patching their destination address and +** registers: tests producing values jump to 'vtarget' (and put their +** values in 'reg'), other tests jump to 'dtarget'. +*/ +const patchlistaux = function(fs, list, vtarget, reg, dtarget) { + while (list !== NO_JUMP) { + let next = getjump(fs, list); + if (patchtestreg(fs, list, reg)) + fixjump(fs, list, vtarget); + else + fixjump(fs, list, dtarget); /* jump to default target */ + list = next; + } +}; + +/* +** Add elements in 'list' to list of pending jumps to "here" +** (current position) +*/ +const luaK_patchtohere = function(fs, list) { + luaK_getlabel(fs); /* mark "here" as a jump target */ + luaK_concat(fs, fs.jpc, list); +}; + +/* +** Path all jumps in 'list' to jump to 'target'. +** (The assert means that we cannot fix a jump to a forward address +** because we only know addresses once code is generated.) +*/ +const luaK_patchlist = function(fs, list, target) { + if (target === fs.pc) /* 'target' is current position? */ + luaK_patchtohere(fs, list); /* add list to pending jumps */ + else { + assert(target < fs.pc); + patchlistaux(fs, list, target, lopcode.NO_REG, target); + } +}; + +/* +** Path all jumps in 'list' to close upvalues up to given 'level' +** (The assertion checks that jumps either were closing nothing +** or were closing higher levels, from inner blocks.) +*/ +const luaK_patchclose = function(fs, list, level) { + level++; /* argument is +1 to reserve 0 as non-op */ + for (; list !== NO_JUMP; list = getjump(fs, list)) { + let ins = fs.f.code[list]; + assert(ins.opcode === OpCodesI.OP_JMP && (ins.A === 0 || i.A >= level); + lopcode.SETARG_A(ins, level); + } +}; + +/* +** Emit instruction 'i', checking for array sizes and saving also its +** line information. Return 'i' position. +*/ +const luaK_code = function(fs, i) { + let f = fs.f; + lcode.dischargejpc(fs); /* 'pc' will change */ + /* put new instruction in code array */ + f.code[fs.pc] = i; + f.lineinfo[fs.pc] = fs.ls.lastline; + return fs.pc++; +}; + +/* +** Format and emit an 'iABC' instruction. (Assertions check consistency +** of parameters versus opcode.) +*/ +const luaK_codeABC = function(fs, o, a, b, c) { + assert(lopcode.getOpMode(o) == lopcode.iABC); + assert(lopcode.getBMode(o) != lopcode.OpArgN || b === 0); + assert(lopcode.getCMode(o) != lopcode.OpArgN || c === 0); + assert(a <= lopcode.MAXARG_A && b <= lopcode.MAXARG_B && c <= lopcode.MAXARG_C); + return luaK_code(fs, lopcode.CREATE_ABC(o, a, b, c)); +}; + +/* +** Format and emit an 'iABx' instruction. +*/ +const luaK_codeABx = function(fs, o, a, bc) { + lua_assert(lopcode.getOpMode(o) == lopcode.iABx || getOpMode(o) == lopcode.iAsBx); + lua_assert(lopcode.getCMode(o) == lopcode.OpArgN); + lua_assert(a <= lopcode.MAXARG_A && bc <= lopcode.MAXARG_Bx); + return luaK_code(fs, lopcode.CREATE_ABx(o, a, bc)); +}; + +const luaK_codeAsBx = function(fs,o,A,sBx) { + return luaK_codeABx(fs, o, A, (sBx) + lopcode.MAXARG_sBx); +}; + +module.exports.NO_JUMP = NO_JUMP; +module.exports.luaK_codeABx = luaK_codeABx; +module.exports.luaK_codeAsBx = luaK_codeAsBx; +module.exports.luaK_getlabel = luaK_getlabel; +module.exports.luaK_jump = luaK_jump; +module.exports.luaK_patchclose = luaK_patchclose; +module.exports.luaK_patchlist = luaK_patchlist; +module.exports.luaK_patchtohere = luaK_patchtohere; +module.exports.luaK_ret = luaK_ret; \ No newline at end of file -- cgit v1.2.3-54-g00ecf