Add Lua source, not compiled yet as libc/libm functions remain unimplemented

1 files changed, 1199 insertions, 0 deletions

diff --git a/src/lib/lua/lcode.c b/src/lib/lua/lcode.c
new file mode 100644
index 0000000..2cd0dd2
--- /dev/null
+++ b/src/lib/lua/lcode.c
@@ -0,0 +1,1199 @@
+/*
+** $Id: lcode.c,v 2.109 2016/05/13 19:09:21 roberto Exp $
+** Code generator for Lua
+** See Copyright Notice in lua.h
+*/
+
+#define lcode_c
+#define LUA_CORE
+
+#include "lprefix.h"
+
+
+#include <math.h>
+#include <stdlib.h>
+
+#include "lua.h"
+
+#include "lcode.h"
+#include "ldebug.h"
+#include "ldo.h"
+#include "lgc.h"
+#include "llex.h"
+#include "lmem.h"
+#include "lobject.h"
+#include "lopcodes.h"
+#include "lparser.h"
+#include "lstring.h"
+#include "ltable.h"
+#include "lvm.h"
+
+
+/* Maximum number of registers in a Lua function (must fit in 8 bits) */
+#define MAXREGS		255
+
+
+#define hasjumps(e)	((e)->t != (e)->f)
+
+
+/*
+** If expression is a numeric constant, fills 'v' with its value
+** and returns 1. Otherwise, returns 0.
+*/
+static int tonumeral(expdesc *e, TValue *v) {
+  if (hasjumps(e))
+    return 0;  /* not a numeral */
+  switch (e->k) {
+    case VKINT:
+      if (v) setivalue(v, e->u.ival);
+      return 1;
+    case VKFLT:
+      if (v) setfltvalue(v, e->u.nval);
+      return 1;
+    default: return 0;
+  }
+}
+
+
+/*
+** Create a OP_LOADNIL instruction, but try to optimize: if the previous
+** instruction is also OP_LOADNIL and ranges are compatible, adjust
+** range of previous instruction instead of emitting a new one. (For
+** instance, 'local a; local b' will generate a single opcode.)
+*/
+void luaK_nil (FuncState *fs, int from, int n) {
+  Instruction *previous;
+  int l = from + n - 1;  /* last register to set nil */
+  if (fs->pc > fs->lasttarget) {  /* no jumps to current position? */
+    previous = &fs->f->code[fs->pc-1];
+    if (GET_OPCODE(*previous) == OP_LOADNIL) {  /* previous is LOADNIL? */
+      int pfrom = GETARG_A(*previous);  /* get previous range */
+      int pl = pfrom + GETARG_B(*previous);
+      if ((pfrom <= from && from <= pl + 1) ||
+          (from <= pfrom && pfrom <= l + 1)) {  /* can connect both? */
+        if (pfrom < from) from = pfrom;  /* from = min(from, pfrom) */
+        if (pl > l) l = pl;  /* l = max(l, pl) */
+        SETARG_A(*previous, from);
+        SETARG_B(*previous, l - from);
+        return;
+      }
+    }  /* else go through */
+  }
+  luaK_codeABC(fs, OP_LOADNIL, from, n - 1, 0);  /* else no optimization */
+}
+
+
+/*
+** Gets the destination address of a jump instruction. Used to traverse
+** a list of jumps.
+*/ 
+static int getjump (FuncState *fs, int pc) {
+  int offset = GETARG_sBx(fs->f->code[pc]);
+  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)
+*/
+static void fixjump (FuncState *fs, int pc, int dest) {
+  Instruction *jmp = &fs->f->code[pc];
+  int offset = dest - (pc + 1);
+  lua_assert(dest != NO_JUMP);
+  if (abs(offset) > MAXARG_sBx)
+    luaX_syntaxerror(fs->ls, "control structure too long");
+  SETARG_sBx(*jmp, offset);
+}
+
+
+/*
+** Concatenate jump-list 'l2' into jump-list 'l1'
+*/
+void luaK_concat (FuncState *fs, int *l1, int l2) {
+  if (l2 == NO_JUMP) return;  /* nothing to concatenate? */
+  else if (*l1 == NO_JUMP)  /* no original list? */
+    *l1 = l2;  /* 'l1' points to 'l2' */
+  else {
+    int list = *l1;
+    int next;
+    while ((next = getjump(fs, list)) != NO_JUMP)  /* find last element */
+      list = next;
+    fixjump(fs, list, l2);  /* last element links to '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.
+*/
+int luaK_jump (FuncState *fs) {
+  int jpc = fs->jpc;  /* save list of jumps to here */
+  int j;
+  fs->jpc = NO_JUMP;  /* no more jumps to here */
+  j = luaK_codeAsBx(fs, OP_JMP, 0, NO_JUMP);
+  luaK_concat(fs, &j, jpc);  /* keep them on hold */
+  return j;
+}
+
+
+/*
+** Code a 'return' instruction
+*/
+void luaK_ret (FuncState *fs, int first, int nret) {
+  luaK_codeABC(fs, OP_RETURN, first, nret+1, 0);
+}
+
+
+/*
+** Code a "conditional jump", that is, a test or comparison opcode
+** followed by a jump. Return jump position.
+*/
+static int condjump (FuncState *fs, OpCode op, int A, int B, int C) {
+  luaK_codeABC(fs, op, A, B, C);
+  return luaK_jump(fs);
+}
+
+
+/*
+** returns current 'pc' and marks it as a jump target (to avoid wrong
+** optimizations with consecutive instructions not in the same basic block).
+*/
+int luaK_getlabel (FuncState *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.
+*/
+static Instruction *getjumpcontrol (FuncState *fs, int pc) {
+  Instruction *pi = &fs->f->code[pc];
+  if (pc >= 1 && testTMode(GET_OPCODE(*(pi-1))))
+    return pi-1;
+  else
+    return pi;
+}
+
+
+/*
+** 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)
+*/
+static int patchtestreg (FuncState *fs, int node, int reg) {
+  Instruction *i = getjumpcontrol(fs, node);
+  if (GET_OPCODE(*i) != OP_TESTSET)
+    return 0;  /* cannot patch other instructions */
+  if (reg != NO_REG && reg != GETARG_B(*i))
+    SETARG_A(*i, reg);
+  else {
+     /* no register to put value or register already has the value;
+        change instruction to simple test */
+    *i = CREATE_ABC(OP_TEST, GETARG_B(*i), 0, GETARG_C(*i));
+  }
+  return 1;
+}
+
+
+/*
+** Traverse a list of tests ensuring no one produces a value
+*/
+static void removevalues (FuncState *fs, int list) {
+  for (; list != NO_JUMP; list = getjump(fs, list))
+      patchtestreg(fs, list, NO_REG);
+}
+
+
+/*
+** 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'.
+*/
+static void patchlistaux (FuncState *fs, int list, int vtarget, int reg,
+                          int dtarget) {
+  while (list != NO_JUMP) {
+    int next = getjump(fs, list);
+    if (patchtestreg(fs, list, reg))
+      fixjump(fs, list, vtarget);
+    else
+      fixjump(fs, list, dtarget);  /* jump to default target */
+    list = next;
+  }
+}
+
+
+/*
+** Ensure all pending jumps to current position are fixed (jumping
+** to current position with no values) and reset list of pending
+** jumps
+*/
+static void dischargejpc (FuncState *fs) {
+  patchlistaux(fs, fs->jpc, fs->pc, NO_REG, fs->pc);
+  fs->jpc = NO_JUMP;
+}
+
+
+/*
+** Add elements in 'list' to list of pending jumps to "here"
+** (current position)
+*/
+void luaK_patchtohere (FuncState *fs, int 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.)
+*/
+void luaK_patchlist (FuncState *fs, int list, int target) {
+  if (target == fs->pc)  /* 'target' is current position? */
+    luaK_patchtohere(fs, list);  /* add list to pending jumps */
+  else {
+    lua_assert(target < fs->pc);
+    patchlistaux(fs, list, target, 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.)
+*/
+void luaK_patchclose (FuncState *fs, int list, int level) {
+  level++;  /* argument is +1 to reserve 0 as non-op */
+  for (; list != NO_JUMP; list = getjump(fs, list)) {
+    lua_assert(GET_OPCODE(fs->f->code[list]) == OP_JMP &&
+                (GETARG_A(fs->f->code[list]) == 0 ||
+                 GETARG_A(fs->f->code[list]) >= level));
+    SETARG_A(fs->f->code[list], level);
+  }
+}
+
+
+/*
+** Emit instruction 'i', checking for array sizes and saving also its
+** line information. Return 'i' position.
+*/
+static int luaK_code (FuncState *fs, Instruction i) {
+  Proto *f = fs->f;
+  dischargejpc(fs);  /* 'pc' will change */
+  /* put new instruction in code array */
+  luaM_growvector(fs->ls->L, f->code, fs->pc, f->sizecode, Instruction,
+                  MAX_INT, "opcodes");
+  f->code[fs->pc] = i;
+  /* save corresponding line information */
+  luaM_growvector(fs->ls->L, f->lineinfo, fs->pc, f->sizelineinfo, int,
+                  MAX_INT, "opcodes");
+  f->lineinfo[fs->pc] = fs->ls->lastline;
+  return fs->pc++;
+}
+
+
+/*
+** Format and emit an 'iABC' instruction. (Assertions check consistency
+** of parameters versus opcode.)
+*/
+int luaK_codeABC (FuncState *fs, OpCode o, int a, int b, int c) {
+  lua_assert(getOpMode(o) == iABC);
+  lua_assert(getBMode(o) != OpArgN || b == 0);
+  lua_assert(getCMode(o) != OpArgN || c == 0);
+  lua_assert(a <= MAXARG_A && b <= MAXARG_B && c <= MAXARG_C);
+  return luaK_code(fs, CREATE_ABC(o, a, b, c));
+}
+
+
+/*
+** Format and emit an 'iABx' instruction.
+*/
+int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {
+  lua_assert(getOpMode(o) == iABx || getOpMode(o) == iAsBx);
+  lua_assert(getCMode(o) == OpArgN);
+  lua_assert(a <= MAXARG_A && bc <= MAXARG_Bx);
+  return luaK_code(fs, CREATE_ABx(o, a, bc));
+}
+
+
+/*
+** Emit an "extra argument" instruction (format 'iAx')
+*/
+static int codeextraarg (FuncState *fs, int a) {
+  lua_assert(a <= MAXARG_Ax);
+  return luaK_code(fs, CREATE_Ax(OP_EXTRAARG, a));
+}
+
+
+/*
+** Emit a "load constant" instruction, using either 'OP_LOADK'
+** (if constant index 'k' fits in 18 bits) or an 'OP_LOADKX'
+** instruction with "extra argument".
+*/
+int luaK_codek (FuncState *fs, int reg, int k) {
+  if (k <= MAXARG_Bx)
+    return luaK_codeABx(fs, OP_LOADK, reg, k);
+  else {
+    int p = luaK_codeABx(fs, OP_LOADKX, reg, 0);
+    codeextraarg(fs, k);
+    return p;
+  }
+}
+
+
+/*
+** Check register-stack level, keeping track of its maximum size
+** in field 'maxstacksize'
+*/
+void luaK_checkstack (FuncState *fs, int n) {
+  int newstack = fs->freereg + n;
+  if (newstack > fs->f->maxstacksize) {
+    if (newstack >= MAXREGS)
+      luaX_syntaxerror(fs->ls,
+        "function or expression needs too many registers");
+    fs->f->maxstacksize = cast_byte(newstack);
+  }
+}
+
+
+/*
+** Reserve 'n' registers in register stack
+*/
+void luaK_reserveregs (FuncState *fs, int n) {
+  luaK_checkstack(fs, n);
+  fs->freereg += n;
+}
+
+
+/*
+** Free register 'reg', if it is neither a constant index nor
+** a local variable.
+)
+*/
+static void freereg (FuncState *fs, int reg) {
+  if (!ISK(reg) && reg >= fs->nactvar) {
+    fs->freereg--;
+    lua_assert(reg == fs->freereg);
+  }
+}
+
+
+/*
+** Free register used by expression 'e' (if any)
+*/
+static void freeexp (FuncState *fs, expdesc *e) {
+  if (e->k == VNONRELOC)
+    freereg(fs, e->u.info);
+}
+
+
+/*
+** Free registers used by expressions 'e1' and 'e2' (if any) in proper
+** order.
+*/
+static void freeexps (FuncState *fs, expdesc *e1, expdesc *e2) {
+  int r1 = (e1->k == VNONRELOC) ? e1->u.info : -1;
+  int r2 = (e2->k == VNONRELOC) ? e2->u.info : -1;
+  if (r1 > r2) {
+    freereg(fs, r1);
+    freereg(fs, r2);
+  }
+  else {
+    freereg(fs, r2);
+    freereg(fs, r1);
+  }
+}
+
+
+/*
+** Add constant 'v' to prototype's list of constants (field 'k').
+** Use scanner's table to cache position of constants in constant list
+** and try to reuse constants. Because some values should not be used
+** as keys (nil cannot be a key, integer keys can collapse with float
+** keys), the caller must provide a useful 'key' for indexing the cache.
+*/
+static int addk (FuncState *fs, TValue *key, TValue *v) {
+  lua_State *L = fs->ls->L;
+  Proto *f = fs->f;
+  TValue *idx = luaH_set(L, fs->ls->h, key);  /* index scanner table */
+  int k, oldsize;
+  if (ttisinteger(idx)) {  /* is there an index there? */
+    k = cast_int(ivalue(idx));
+    /* correct value? (warning: must distinguish floats from integers!) */
+    if (k < fs->nk && ttype(&f->k[k]) == ttype(v) &&
+                      luaV_rawequalobj(&f->k[k], v))
+      return k;  /* reuse index */
+  }
+  /* constant not found; create a new entry */
+  oldsize = f->sizek;
+  k = fs->nk;
+  /* numerical value does not need GC barrier;
+     table has no metatable, so it does not need to invalidate cache */
+  setivalue(idx, k);
+  luaM_growvector(L, f->k, k, f->sizek, TValue, MAXARG_Ax, "constants");
+  while (oldsize < f->sizek) setnilvalue(&f->k[oldsize++]);
+  setobj(L, &f->k[k], v);
+  fs->nk++;
+  luaC_barrier(L, f, v);
+  return k;
+}
+
+
+/*
+** Add a string to list of constants and return its index.
+*/
+int luaK_stringK (FuncState *fs, TString *s) {
+  TValue o;
+  setsvalue(fs->ls->L, &o, s);
+  return addk(fs, &o, &o);  /* use string itself as key */
+}
+
+
+/*
+** Add an integer to list of constants and return its index.
+** Integers use userdata as keys to avoid collision with floats with
+** same value; conversion to 'void*' is used only for hashing, so there
+** are no "precision" problems.
+*/
+int luaK_intK (FuncState *fs, lua_Integer n) {
+  TValue k, o;
+  setpvalue(&k, cast(void*, cast(size_t, n)));
+  setivalue(&o, n);
+  return addk(fs, &k, &o);
+}
+
+/*
+** Add a float to list of constants and return its index.
+*/
+static int luaK_numberK (FuncState *fs, lua_Number r) {
+  TValue o;
+  setfltvalue(&o, r);
+  return addk(fs, &o, &o);  /* use number itself as key */
+}
+
+
+/*
+** Add a boolean to list of constants and return its index.
+*/
+static int boolK (FuncState *fs, int b) {
+  TValue o;
+  setbvalue(&o, b);
+  return addk(fs, &o, &o);  /* use boolean itself as key */
+}
+
+
+/*
+** Add nil to list of constants and return its index.
+*/
+static int nilK (FuncState *fs) {
+  TValue k, v;
+  setnilvalue(&v);
+  /* cannot use nil as key; instead use table itself to represent nil */
+  sethvalue(fs->ls->L, &k, fs->ls->h);
+  return addk(fs, &k, &v);
+}
+
+
+/*
+** Fix an expression to return the number of results 'nresults'.
+** Either 'e' is a multi-ret expression (function call or vararg)
+** or 'nresults' is LUA_MULTRET (as any expression can satisfy that).
+*/
+void luaK_setreturns (FuncState *fs, expdesc *e, int nresults) {
+  if (e->k == VCALL) {  /* expression is an open function call? */
+    SETARG_C(getinstruction(fs, e), nresults + 1);
+  }
+  else if (e->k == VVARARG) {
+    Instruction *pc = &getinstruction(fs, e);
+    SETARG_B(*pc, nresults + 1);
+    SETARG_A(*pc, fs->freereg);
+    luaK_reserveregs(fs, 1);
+  }
+  else lua_assert(nresults == LUA_MULTRET);
+}
+
+
+/*
+** Fix an expression to return one result.
+** If expression is not a multi-ret expression (function call or
+** vararg), it already returns one result, so nothing needs to be done.
+** Function calls become VNONRELOC expressions (as its result comes
+** fixed in the base register of the call), while vararg expressions
+** become VRELOCABLE (as OP_VARARG puts its results where it wants).
+** (Calls are created returning one result, so that does not need
+** to be fixed.)
+*/
+void luaK_setoneret (FuncState *fs, expdesc *e) {
+  if (e->k == VCALL) {  /* expression is an open function call? */
+    /* already returns 1 value */
+    lua_assert(GETARG_C(getinstruction(fs, e)) == 2);
+    e->k = VNONRELOC;  /* result has fixed position */
+    e->u.info = GETARG_A(getinstruction(fs, e));
+  }
+  else if (e->k == VVARARG) {
+    SETARG_B(getinstruction(fs, e), 2);
+    e->k = VRELOCABLE;  /* can relocate its simple result */
+  }
+}
+
+
+/*
+** Ensure that expression 'e' is not a variable.
+*/
+void luaK_dischargevars (FuncState *fs, expdesc *e) {
+  switch (e->k) {
+    case VLOCAL: {  /* already in a register */
+      e->k = VNONRELOC;  /* becomes a non-relocatable value */
+      break;
+    }
+    case VUPVAL: {  /* move value to some (pending) register */
+      e->u.info = luaK_codeABC(fs, OP_GETUPVAL, 0, e->u.info, 0);
+      e->k = VRELOCABLE;
+      break;
+    }
+    case VINDEXED: {
+      OpCode op;
+      freereg(fs, e->u.ind.idx);
+      if (e->u.ind.vt == VLOCAL) {  /* is 't' in a register? */
+        freereg(fs, e->u.ind.t);
+        op = OP_GETTABLE;
+      }
+      else {
+        lua_assert(e->u.ind.vt == VUPVAL);
+        op = OP_GETTABUP;  /* 't' is in an upvalue */
+      }
+      e->u.info = luaK_codeABC(fs, op, 0, e->u.ind.t, e->u.ind.idx);
+      e->k = VRELOCABLE;
+      break;
+    }
+    case VVARARG: case VCALL: {
+      luaK_setoneret(fs, e);
+      break;
+    }
+    default: break;  /* there is one value available (somewhere) */
+  }
+}
+
+
+/*
+** Ensures expression value is in register 'reg' (and therefore
+** 'e' will become a non-relocatable expression).
+*/
+static void discharge2reg (FuncState *fs, expdesc *e, int reg) {
+  luaK_dischargevars(fs, e);
+  switch (e->k) {
+    case VNIL: {
+      luaK_nil(fs, reg, 1);
+      break;
+    }
+    case VFALSE: case VTRUE: {
+      luaK_codeABC(fs, OP_LOADBOOL, reg, e->k == VTRUE, 0);
+      break;
+    }
+    case VK: {
+      luaK_codek(fs, reg, e->u.info);
+      break;
+    }
+    case VKFLT: {
+      luaK_codek(fs, reg, luaK_numberK(fs, e->u.nval));
+      break;
+    }
+    case VKINT: {
+      luaK_codek(fs, reg, luaK_intK(fs, e->u.ival));
+      break;
+    }
+    case VRELOCABLE: {
+      Instruction *pc = &getinstruction(fs, e);
+      SETARG_A(*pc, reg);  /* instruction will put result in 'reg' */
+      break;
+    }
+    case VNONRELOC: {
+      if (reg != e->u.info)
+        luaK_codeABC(fs, OP_MOVE, reg, e->u.info, 0);
+      break;
+    }
+    default: {
+      lua_assert(e->k == VJMP);
+      return;  /* nothing to do... */
+    }
+  }
+  e->u.info = reg;
+  e->k = VNONRELOC;
+}
+
+
+/*
+** Ensures expression value is in any register.
+*/
+static void discharge2anyreg (FuncState *fs, expdesc *e) {
+  if (e->k != VNONRELOC) {  /* no fixed register yet? */
+    luaK_reserveregs(fs, 1);  /* get a register */
+    discharge2reg(fs, e, fs->freereg-1);  /* put value there */
+  }
+}
+
+
+static int code_loadbool (FuncState *fs, int A, int b, int jump) {
+  luaK_getlabel(fs);  /* those instructions may be jump targets */
+  return luaK_codeABC(fs, OP_LOADBOOL, A, b, jump);
+}
+
+
+/*
+** check whether list has any jump that do not produce a value
+** or produce an inverted value
+*/
+static int need_value (FuncState *fs, int list) {
+  for (; list != NO_JUMP; list = getjump(fs, list)) {
+    Instruction i = *getjumpcontrol(fs, list);
+    if (GET_OPCODE(i) != OP_TESTSET) return 1;
+  }
+  return 0;  /* not found */
+}
+
+
+/*
+** Ensures final expression result (including results from its jump
+** lists) is in register 'reg'.
+** If expression has jumps, need to patch these jumps either to
+** its final position or to "load" instructions (for those tests
+** that do not produce values).
+*/
+static void exp2reg (FuncState *fs, expdesc *e, int reg) {
+  discharge2reg(fs, e, reg);
+  if (e->k == VJMP)  /* expression itself is a test? */
+    luaK_concat(fs, &e->t, e->u.info);  /* put this jump in 't' list */
+  if (hasjumps(e)) {
+    int final;  /* position after whole expression */
+    int p_f = NO_JUMP;  /* position of an eventual LOAD false */
+    int p_t = NO_JUMP;  /* position of an eventual LOAD true */
+    if (need_value(fs, e->t) || need_value(fs, e->f)) {
+      int fj = (e->k == VJMP) ? NO_JUMP : luaK_jump(fs);
+      p_f = code_loadbool(fs, reg, 0, 1);
+      p_t = code_loadbool(fs, reg, 1, 0);
+      luaK_patchtohere(fs, fj);
+    }
+    final = luaK_getlabel(fs);
+    patchlistaux(fs, e->f, final, reg, p_f);
+    patchlistaux(fs, e->t, final, reg, p_t);
+  }
+  e->f = e->t = NO_JUMP;
+  e->u.info = reg;
+  e->k = VNONRELOC;
+}
+
+
+/*
+** Ensures final expression result (including results from its jump
+** lists) is in next available register.
+*/
+void luaK_exp2nextreg (FuncState *fs, expdesc *e) {
+  luaK_dischargevars(fs, e);
+  freeexp(fs, e);
+  luaK_reserveregs(fs, 1);
+  exp2reg(fs, e, fs->freereg - 1);
+}
+
+
+/*
+** Ensures final expression result (including results from its jump
+** lists) is in some (any) register and return that register.
+*/
+int luaK_exp2anyreg (FuncState *fs, expdesc *e) {
+  luaK_dischargevars(fs, e);
+  if (e->k == VNONRELOC) {  /* expression already has a register? */
+    if (!hasjumps(e))  /* no jumps? */
+      return e->u.info;  /* result is already in a register */
+    if (e->u.info >= fs->nactvar) {  /* reg. is not a local? */
+      exp2reg(fs, e, e->u.info);  /* put final result in it */
+      return e->u.info;
+    }
+  }
+  luaK_exp2nextreg(fs, e);  /* otherwise, use next available register */
+  return e->u.info;
+}
+
+
+/*
+** Ensures final expression result is either in a register or in an
+** upvalue.
+*/
+void luaK_exp2anyregup (FuncState *fs, expdesc *e) {
+  if (e->k != VUPVAL || hasjumps(e))
+    luaK_exp2anyreg(fs, e);
+}
+
+
+/*
+** Ensures final expression result is either in a register or it is
+** a constant.
+*/
+void luaK_exp2val (FuncState *fs, expdesc *e) {
+  if (hasjumps(e))
+    luaK_exp2anyreg(fs, e);
+  else
+    luaK_dischargevars(fs, e);
+}
+
+
+/*
+** Ensures final expression result is in a valid R/K index
+** (that is, it is either in a register or in 'k' with an index
+** in the range of R/K indices).
+** Returns R/K index.
+*/  
+int luaK_exp2RK (FuncState *fs, expdesc *e) {
+  luaK_exp2val(fs, e);
+  switch (e->k) {  /* move constants to 'k' */
+    case VTRUE: e->u.info = boolK(fs, 1); goto vk;
+    case VFALSE: e->u.info = boolK(fs, 0); goto vk;
+    case VNIL: e->u.info = nilK(fs); goto vk;
+    case VKINT: e->u.info = luaK_intK(fs, e->u.ival); goto vk;
+    case VKFLT: e->u.info = luaK_numberK(fs, e->u.nval); goto vk;
+    case VK:
+     vk:
+      e->k = VK;
+      if (e->u.info <= MAXINDEXRK)  /* constant fits in 'argC'? */
+        return RKASK(e->u.info);
+      else break;
+    default: break;
+  }
+  /* not a constant in the right range: put it in a register */
+  return luaK_exp2anyreg(fs, e);
+}
+
+
+/*
+** Generate code to store result of expression 'ex' into variable 'var'.
+*/
+void luaK_storevar (FuncState *fs, expdesc *var, expdesc *ex) {
+  switch (var->k) {
+    case VLOCAL: {
+      freeexp(fs, ex);
+      exp2reg(fs, ex, var->u.info);  /* compute 'ex' into proper place */
+      return;
+    }
+    case VUPVAL: {
+      int e = luaK_exp2anyreg(fs, ex);
+      luaK_codeABC(fs, OP_SETUPVAL, e, var->u.info, 0);
+      break;
+    }
+    case VINDEXED: {
+      OpCode op = (var->u.ind.vt == VLOCAL) ? OP_SETTABLE : OP_SETTABUP;
+      int e = luaK_exp2RK(fs, ex);
+      luaK_codeABC(fs, op, var->u.ind.t, var->u.ind.idx, e);
+      break;
+    }
+    default: lua_assert(0);  /* invalid var kind to store */
+  }
+  freeexp(fs, ex);
+}
+
+
+/*
+** Emit SELF instruction (convert expression 'e' into 'e:key(e,').
+*/
+void luaK_self (FuncState *fs, expdesc *e, expdesc *key) {
+  int ereg;
+  luaK_exp2anyreg(fs, e);
+  ereg = e->u.info;  /* register where 'e' was placed */
+  freeexp(fs, e);
+  e->u.info = fs->freereg;  /* base register for op_self */
+  e->k = VNONRELOC;  /* self expression has a fixed register */
+  luaK_reserveregs(fs, 2);  /* function and 'self' produced by op_self */
+  luaK_codeABC(fs, OP_SELF, e->u.info, ereg, luaK_exp2RK(fs, key));
+  freeexp(fs, key);
+}
+
+
+/*
+** Negate condition 'e' (where 'e' is a comparison).
+*/
+static void negatecondition (FuncState *fs, expdesc *e) {
+  Instruction *pc = getjumpcontrol(fs, e->u.info);
+  lua_assert(testTMode(GET_OPCODE(*pc)) && GET_OPCODE(*pc) != OP_TESTSET &&
+                                           GET_OPCODE(*pc) != OP_TEST);
+  SETARG_A(*pc, !(GETARG_A(*pc)));
+}
+
+
+/*
+** Emit instruction to jump if 'e' is 'cond' (that is, if 'cond'
+** is true, code will jump if 'e' is true.) Return jump position.
+** Optimize when 'e' is 'not' something, inverting the condition
+** and removing the 'not'.
+*/
+static int jumponcond (FuncState *fs, expdesc *e, int cond) {
+  if (e->k == VRELOCABLE) {
+    Instruction ie = getinstruction(fs, e);
+    if (GET_OPCODE(ie) == OP_NOT) {
+      fs->pc--;  /* remove previous OP_NOT */
+      return condjump(fs, OP_TEST, GETARG_B(ie), 0, !cond);
+    }
+    /* else go through */
+  }
+  discharge2anyreg(fs, e);
+  freeexp(fs, e);
+  return condjump(fs, OP_TESTSET, NO_REG, e->u.info, cond);
+}
+
+
+/*
+** Emit code to go through if 'e' is true, jump otherwise.
+*/
+void luaK_goiftrue (FuncState *fs, expdesc *e) {
+  int pc;  /* pc of new jump */
+  luaK_dischargevars(fs, e);
+  switch (e->k) {
+    case VJMP: {  /* condition? */
+      negatecondition(fs, e);  /* jump when it is false */
+      pc = e->u.info;  /* save jump position */
+      break;
+    }
+    case VK: case VKFLT: case VKINT: case VTRUE: {
+      pc = NO_JUMP;  /* always true; do nothing */
+      break;
+    }
+    default: {
+      pc = jumponcond(fs, e, 0);  /* jump when false */
+      break;
+    }
+  }
+  luaK_concat(fs, &e->f, pc);  /* insert new jump in false list */
+  luaK_patchtohere(fs, e->t);  /* true list jumps to here (to go through) */
+  e->t = NO_JUMP;
+}
+
+
+/*
+** Emit code to go through if 'e' is false, jump otherwise.
+*/
+void luaK_goiffalse (FuncState *fs, expdesc *e) {
+  int pc;  /* pc of new jump */
+  luaK_dischargevars(fs, e);
+  switch (e->k) {
+    case VJMP: {
+      pc = e->u.info;  /* already jump if true */
+      break;
+    }
+    case VNIL: case VFALSE: {
+      pc = NO_JUMP;  /* always false; do nothing */
+      break;
+    }
+    default: {
+      pc = jumponcond(fs, e, 1);  /* jump if true */
+      break;
+    }
+  }
+  luaK_concat(fs, &e->t, pc);  /* insert new jump in 't' list */
+  luaK_patchtohere(fs, e->f);  /* false list jumps to here (to go through) */
+  e->f = NO_JUMP;
+}
+
+
+/*
+** Code 'not e', doing constant folding.
+*/
+static void codenot (FuncState *fs, expdesc *e) {
+  luaK_dischargevars(fs, e);
+  switch (e->k) {
+    case VNIL: case VFALSE: {
+      e->k = VTRUE;  /* true == not nil == not false */
+      break;
+    }
+    case VK: case VKFLT: case VKINT: case VTRUE: {
+      e->k = VFALSE;  /* false == not "x" == not 0.5 == not 1 == not true */
+      break;
+    }
+    case VJMP: {
+      negatecondition(fs, e);
+      break;
+    }
+    case VRELOCABLE:
+    case VNONRELOC: {
+      discharge2anyreg(fs, e);
+      freeexp(fs, e);
+      e->u.info = luaK_codeABC(fs, OP_NOT, 0, e->u.info, 0);
+      e->k = VRELOCABLE;
+      break;
+    }
+    default: lua_assert(0);  /* cannot happen */
+  }
+  /* interchange true and false lists */
+  { int temp = e->f; e->f = e->t; e->t = temp; }
+  removevalues(fs, e->f);  /* values are useless when negated */
+  removevalues(fs, e->t);
+}
+
+
+/*
+** Create expression 't[k]'. 't' must have its final result already in a
+** register or upvalue.
+*/
+void luaK_indexed (FuncState *fs, expdesc *t, expdesc *k) {
+  lua_assert(!hasjumps(t) && (vkisinreg(t->k) || t->k == VUPVAL));
+  t->u.ind.t = t->u.info;  /* register or upvalue index */
+  t->u.ind.idx = luaK_exp2RK(fs, k);  /* R/K index for key */
+  t->u.ind.vt = (t->k == VUPVAL) ? VUPVAL : VLOCAL;
+  t->k = VINDEXED;
+}
+
+
+/*
+** Return false if folding can raise an error.
+** Bitwise operations need operands convertible to integers; division
+** operations cannot have 0 as divisor.
+*/
+static int validop (int op, TValue *v1, TValue *v2) {
+  switch (op) {
+    case LUA_OPBAND: case LUA_OPBOR: case LUA_OPBXOR:
+    case LUA_OPSHL: case LUA_OPSHR: case LUA_OPBNOT: {  /* conversion errors */
+      lua_Integer i;
+      return (tointeger(v1, &i) && tointeger(v2, &i));
+    }
+    case LUA_OPDIV: case LUA_OPIDIV: case LUA_OPMOD:  /* division by 0 */
+      return (nvalue(v2) != 0);
+    default: return 1;  /* everything else is valid */
+  }
+}
+
+
+/*
+** Try to "constant-fold" an operation; return 1 iff successful.
+** (In this case, 'e1' has the final result.)
+*/
+static int constfolding (FuncState *fs, int op, expdesc *e1, expdesc *e2) {
+  TValue v1, v2, res;
+  if (!tonumeral(e1, &v1) || !tonumeral(e2, &v2) || !validop(op, &v1, &v2))
+    return 0;  /* non-numeric operands or not safe to fold */
+  luaO_arith(fs->ls->L, op, &v1, &v2, &res);  /* does operation */
+  if (ttisinteger(&res)) {
+    e1->k = VKINT;
+    e1->u.ival = ivalue(&res);
+  }
+  else {  /* folds neither NaN nor 0.0 (to avoid problems with -0.0) */
+    lua_Number n = fltvalue(&res);
+    if (luai_numisnan(n) || n == 0)
+      return 0;
+    e1->k = VKFLT;
+    e1->u.nval = n;
+  }
+  return 1;
+}
+
+
+/*
+** Emit code for unary expressions that "produce values"
+** (everything but 'not').
+** Expression to produce final result will be encoded in 'e'.
+*/
+static void codeunexpval (FuncState *fs, OpCode op, expdesc *e, int line) {
+  int r = luaK_exp2anyreg(fs, e);  /* opcodes operate only on registers */
+  freeexp(fs, e);
+  e->u.info = luaK_codeABC(fs, op, 0, r, 0);  /* generate opcode */
+  e->k = VRELOCABLE;  /* all those operations are relocatable */
+  luaK_fixline(fs, line);
+}
+
+
+/*
+** Emit code for binary expressions that "produce values"
+** (everything but logical operators 'and'/'or' and comparison
+** operators).
+** Expression to produce final result will be encoded in 'e1'.
+*/
+static void codebinexpval (FuncState *fs, OpCode op,
+                           expdesc *e1, expdesc *e2, int line) {
+  int rk1 = luaK_exp2RK(fs, e1);  /* both operands are "RK" */
+  int rk2 = luaK_exp2RK(fs, e2);
+  freeexps(fs, e1, e2);
+  e1->u.info = luaK_codeABC(fs, op, 0, rk1, rk2);  /* generate opcode */
+  e1->k = VRELOCABLE;  /* all those operations are relocatable */
+  luaK_fixline(fs, line);
+}
+
+
+/*
+** Emit code for comparisons.
+** 'e1' was already put in R/K form by 'luaK_infix'.
+*/
+static void codecomp (FuncState *fs, BinOpr opr, expdesc *e1, expdesc *e2) {
+  int rk1 = (e1->k == VK) ? RKASK(e1->u.info)
+                          : check_exp(e1->k == VNONRELOC, e1->u.info);
+  int rk2 = luaK_exp2RK(fs, e2);
+  freeexps(fs, e1, e2);
+  switch (opr) {
+    case OPR_NE: {  /* '(a ~= b)' ==> 'not (a == b)' */
+      e1->u.info = condjump(fs, OP_EQ, 0, rk1, rk2);
+      break;
+    }
+    case OPR_GT: case OPR_GE: {
+      /* '(a > b)' ==> '(b < a)';  '(a >= b)' ==> '(b <= a)' */
+      OpCode op = cast(OpCode, (opr - OPR_NE) + OP_EQ);
+      e1->u.info = condjump(fs, op, 1, rk2, rk1);  /* invert operands */
+      break;
+    }
+    default: {  /* '==', '<', '<=' use their own opcodes */
+      OpCode op = cast(OpCode, (opr - OPR_EQ) + OP_EQ);
+      e1->u.info = condjump(fs, op, 1, rk1, rk2);
+      break;
+    }
+  }
+  e1->k = VJMP;
+}
+
+
+/*
+** Aplly prefix operation 'op' to expression 'e'.
+*/
+void luaK_prefix (FuncState *fs, UnOpr op, expdesc *e, int line) {
+  static expdesc ef = {VKINT, {0}, NO_JUMP, NO_JUMP};  /* fake 2nd operand */
+  switch (op) {
+    case OPR_MINUS: case OPR_BNOT:
+      if (constfolding(fs, op + LUA_OPUNM, e, &ef))
+        break;
+      /* FALLTHROUGH */
+    case OPR_LEN:
+      codeunexpval(fs, cast(OpCode, op + OP_UNM), e, line);
+      break;
+    case OPR_NOT: codenot(fs, e); break;
+    default: lua_assert(0);
+  }
+}
+
+
+/*
+** Process 1st operand 'v' of binary operation 'op' before reading
+** 2nd operand.
+*/
+void luaK_infix (FuncState *fs, BinOpr op, expdesc *v) {
+  switch (op) {
+    case OPR_AND: {
+      luaK_goiftrue(fs, v);  /* go ahead only if 'v' is true */
+      break;
+    }
+    case OPR_OR: {
+      luaK_goiffalse(fs, v);  /* go ahead only if 'v' is false */
+      break;
+    }
+    case OPR_CONCAT: {
+      luaK_exp2nextreg(fs, v);  /* operand must be on the 'stack' */
+      break;
+    }
+    case OPR_ADD: case OPR_SUB:
+    case OPR_MUL: case OPR_DIV: case OPR_IDIV:
+    case OPR_MOD: case OPR_POW:
+    case OPR_BAND: case OPR_BOR: case OPR_BXOR:
+    case OPR_SHL: case OPR_SHR: {
+      if (!tonumeral(v, NULL))
+        luaK_exp2RK(fs, v);
+      /* else keep numeral, which may be folded with 2nd operand */
+      break;
+    }
+    default: {
+      luaK_exp2RK(fs, v);
+      break;
+    }
+  }
+}
+
+
+/*
+** Finalize code for binary operation, after reading 2nd operand.
+** For '(a .. b .. c)' (which is '(a .. (b .. c))', because
+** concatenation is right associative), merge second CONCAT into first
+** one.
+*/
+void luaK_posfix (FuncState *fs, BinOpr op,
+                  expdesc *e1, expdesc *e2, int line) {
+  switch (op) {
+    case OPR_AND: {
+      lua_assert(e1->t == NO_JUMP);  /* list closed by 'luK_infix' */
+      luaK_dischargevars(fs, e2);
+      luaK_concat(fs, &e2->f, e1->f);
+      *e1 = *e2;
+      break;
+    }
+    case OPR_OR: {
+      lua_assert(e1->f == NO_JUMP);  /* list closed by 'luK_infix' */
+      luaK_dischargevars(fs, e2);
+      luaK_concat(fs, &e2->t, e1->t);
+      *e1 = *e2;
+      break;
+    }
+    case OPR_CONCAT: {
+      luaK_exp2val(fs, e2);
+      if (e2->k == VRELOCABLE &&
+          GET_OPCODE(getinstruction(fs, e2)) == OP_CONCAT) {
+        lua_assert(e1->u.info == GETARG_B(getinstruction(fs, e2))-1);
+        freeexp(fs, e1);
+        SETARG_B(getinstruction(fs, e2), e1->u.info);
+        e1->k = VRELOCABLE; e1->u.info = e2->u.info;
+      }
+      else {
+        luaK_exp2nextreg(fs, e2);  /* operand must be on the 'stack' */
+        codebinexpval(fs, OP_CONCAT, e1, e2, line);
+      }
+      break;
+    }
+    case OPR_ADD: case OPR_SUB: case OPR_MUL: case OPR_DIV:
+    case OPR_IDIV: case OPR_MOD: case OPR_POW:
+    case OPR_BAND: case OPR_BOR: case OPR_BXOR:
+    case OPR_SHL: case OPR_SHR: {
+      if (!constfolding(fs, op + LUA_OPADD, e1, e2))
+        codebinexpval(fs, cast(OpCode, op + OP_ADD), e1, e2, line);
+      break;
+    }
+    case OPR_EQ: case OPR_LT: case OPR_LE:
+    case OPR_NE: case OPR_GT: case OPR_GE: {
+      codecomp(fs, op, e1, e2);
+      break;
+    }
+    default: lua_assert(0);
+  }
+}
+
+
+/*
+** Change line information associated with current position.
+*/
+void luaK_fixline (FuncState *fs, int line) {
+  fs->f->lineinfo[fs->pc - 1] = line;
+}
+
+
+/*
+** Emit a SETLIST instruction.
+** 'base' is register that keeps table;
+** 'nelems' is #table plus those to be stored now;
+** 'tostore' is number of values (in registers 'base + 1',...) to add to
+** table (or LUA_MULTRET to add up to stack top).
+*/
+void luaK_setlist (FuncState *fs, int base, int nelems, int tostore) {
+  int c =  (nelems - 1)/LFIELDS_PER_FLUSH + 1;
+  int b = (tostore == LUA_MULTRET) ? 0 : tostore;
+  lua_assert(tostore != 0 && tostore <= LFIELDS_PER_FLUSH);
+  if (c <= MAXARG_C)
+    luaK_codeABC(fs, OP_SETLIST, base, b, c);
+  else if (c <= MAXARG_Ax) {
+    luaK_codeABC(fs, OP_SETLIST, base, b, 0);
+    codeextraarg(fs, c);
+  }
+  else
+    luaX_syntaxerror(fs->ls, "constructor too long");
+  fs->freereg = base + 1;  /* free registers with list values */
+}
+