Lua 5.3.0-rc0

Lua Team committed 11 years ago

Commit 17ba7311 parent 10f306357 files · +1476 −1139Browse files

Showing the changes to src/lcode.c (1 of 57 files). Show all

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 /*
-** $Id: lcode.c,v 2.90 2014/05/08 18:58:46 roberto Exp $
+** $Id: lcode.c,v 2.97 2014/11/24 14:59:22 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>
-#define lcode_c
-#define LUA_CORE
 #include "lua.h"
 #include "lcode.h"
 #include "lvm.h"
-/* test for x == -0 */
+/* Maximum number of registers in a Lua function */
+#define MAXREGS		250
+/* test for x == -0 ('signbit' needs 'math.h') */
 #if defined(signbit)
 #define isminuszero(x)	((x) == 0.0 && signbit(x))
 #else
 /*
-** returns current `pc' and marks it as a jump target (to avoid wrong
+** 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) {
 static int luaK_code (FuncState *fs, Instruction i) {
   Proto *f = fs->f;
-  dischargejpc(fs);  /* `pc' will change */
+  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");
 void luaK_checkstack (FuncState *fs, int n) {
   int newstack = fs->freereg + n;
   if (newstack > fs->f->maxstacksize) {
-    if (newstack >= MAXSTACK)
+    if (newstack >= MAXREGS)
       luaX_syntaxerror(fs->ls, "function or expression too complex");
     fs->f->maxstacksize = cast_byte(newstack);
   }
 static void exp2reg (FuncState *fs, expdesc *e, int reg) {
   discharge2reg(fs, e, reg);
   if (e->k == VJMP)
-    luaK_concat(fs, &e->t, e->u.info);  /* put this jump in `t' list */
+    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 */
     }
     case VK: {
      vk:
-      if (e->u.info <= MAXINDEXRK)  /* constant fits in argC? */
+      if (e->u.info <= MAXINDEXRK)  /* constant fits in 'argC'? */
         return RKASK(e->u.info);
       else break;
     }
       break;
     }
   }
-  luaK_concat(fs, &e->f, pc);  /* insert last jump in `f' list */
+  luaK_concat(fs, &e->f, pc);  /* insert last jump in 'f' list */
   luaK_patchtohere(fs, e->t);
   e->t = NO_JUMP;
 }
       break;
     }
   }
-  luaK_concat(fs, &e->t, pc);  /* insert last jump in `t' list */
+  luaK_concat(fs, &e->t, pc);  /* insert last jump in 't' list */
   luaK_patchtohere(fs, e->f);
   e->f = NO_JUMP;
 }
                             (cast_void(tonumber(v2, &b)), b)))
     return 0;
   switch (op) {
-    case LUA_OPIDIV:  /* division by 0 and conversion errors */
-      return (tointeger(v1, &i) && tointeger(v2, &i) && i != 0);
     case LUA_OPBAND: case LUA_OPBOR: case LUA_OPBXOR:
     case LUA_OPSHL: case LUA_OPSHR: case LUA_OPBNOT:  /* conversion errors */
       return (tointeger(v1, &i) && tointeger(v2, &i));
-    case LUA_OPMOD:  /* integer module by 0 */
+    case LUA_OPIDIV: case LUA_OPMOD:  /* integer division by 0 */
       return !(ttisinteger(v1) && ttisinteger(v2) && ivalue(v2) == 0);
     default: return 1;  /* everything else is valid */
   }
 }
-static void codearith (FuncState *fs, OpCode op,
+/*
-                       expdesc *e1, expdesc *e2, int line) {
+** Code for binary and unary expressions that "produce values"
-  if (!constfolding(fs, op - OP_ADD + LUA_OPADD, e1, e2)) {
+** (arithmetic operations, bitwise operations, concat, length). First
+** try to do constant folding (only for numeric [arithmetic and
+** bitwise] operations, which is what 'lua_arith' accepts).
+** Expression to produce final result will be encoded in 'e1'.
+*/
+static void codeexpval (FuncState *fs, OpCode op,
+                        expdesc *e1, expdesc *e2, int line) {
+  lua_assert(op >= OP_ADD);
+  if (op <= OP_BNOT && constfolding(fs, op - OP_ADD + LUA_OPADD, e1, e2))
+    return;  /* result has been folded */
+  else {
     int o1, o2;
-    if (op == OP_UNM || op == OP_BNOT || op == OP_LEN) {
+    /* move operands to registers (if needed) */
-      o2 = 0;
+    if (op == OP_UNM || op == OP_BNOT || op == OP_LEN) {  /* unary op? */
+      o2 = 0;  /* no second expression */
       o1 = luaK_exp2anyreg(fs, e1);  /* cannot operate on constants */
     }
     else {  /* regular case (binary operators) */
-      o2 = luaK_exp2RK(fs, e2);
+      o2 = luaK_exp2RK(fs, e2);  /* both operands are "RK" */
       o1 = luaK_exp2RK(fs, e1);
     }
-    if (o1 > o2) {
+    if (o1 > o2) {  /* free registers in proper order */
       freeexp(fs, e1);
       freeexp(fs, e2);
     }
       freeexp(fs, e2);
       freeexp(fs, e1);
     }
-    e1->u.info = luaK_codeABC(fs, op, 0, o1, o2);
+    e1->u.info = luaK_codeABC(fs, op, 0, o1, o2);  /* generate opcode */
-    e1->k = VRELOCABLE;
+    e1->k = VRELOCABLE;  /* all those operations are relocable */
     luaK_fixline(fs, line);
   }
 }
   freeexp(fs, e2);
   freeexp(fs, e1);
   if (cond == 0 && op != OP_EQ) {
-    int temp;  /* exchange args to replace by `<' or `<=' */
+    int temp;  /* exchange args to replace by '<' or '<=' */
     temp = o1; o1 = o2; o2 = temp;  /* o1 <==> o2 */
     cond = 1;
   }
   e2.t = e2.f = NO_JUMP; e2.k = VKINT; e2.u.ival = 0;
   switch (op) {
     case OPR_MINUS: case OPR_BNOT: case OPR_LEN: {
-      codearith(fs, cast(OpCode, (op - OPR_MINUS) + OP_UNM), e, &e2, line);
+      codeexpval(fs, cast(OpCode, (op - OPR_MINUS) + OP_UNM), e, &e2, line);
       break;
     }
     case OPR_NOT: codenot(fs, e); break;
       break;
     }
     case OPR_CONCAT: {
-      luaK_exp2nextreg(fs, v);  /* operand must be on the `stack' */
+      luaK_exp2nextreg(fs, v);  /* operand must be on the 'stack' */
       break;
     }
     case OPR_ADD: case OPR_SUB:
       }
       else {
         luaK_exp2nextreg(fs, e2);  /* operand must be on the 'stack' */
-        codearith(fs, OP_CONCAT, e1, e2, line);
+        codeexpval(fs, OP_CONCAT, e1, e2, line);
       }
       break;
     }
     case OPR_IDIV: case OPR_MOD: case OPR_POW:
     case OPR_BAND: case OPR_BOR: case OPR_BXOR:
     case OPR_SHL: case OPR_SHR: {
-      codearith(fs, cast(OpCode, (op - OPR_ADD) + OP_ADD), e1, e2, line);
+      codeexpval(fs, cast(OpCode, (op - OPR_ADD) + OP_ADD), e1, e2, line);
       break;
     }
     case OPR_EQ: case OPR_LT: case OPR_LE: {

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