commit f8c1c1469aac2253f0787c0cb7cc228b1a57e738
parent 4b6928e7f524e2c2740fc1f9d16e130e0e2f4172
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Fri, 15 Dec 2017 16:53:21 -0200
some cleaning on signed opcode parameters
Diffstat:
3 files changed, 50 insertions(+), 27 deletions(-)
diff --git a/lcode.c b/lcode.c
@@ -1,5 +1,5 @@
/*
-** $Id: lcode.c,v 2.143 2017/12/13 18:32:09 roberto Exp roberto $
+** $Id: lcode.c,v 2.144 2017/12/14 14:24:02 roberto Exp roberto $
** Code generator for Lua
** See Copyright Notice in lua.h
*/
@@ -108,7 +108,7 @@ 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_sJ)
+ if (!(-OFFSET_sJ <= offset && offset <= MAXARG_sJ - OFFSET_sJ))
luaX_syntaxerror(fs->ls, "control structure too long");
lua_assert(GET_OPCODE(*jmp) == OP_JMP);
SETARG_sJ(*jmp, offset);
@@ -360,7 +360,7 @@ int luaK_codeABCk (FuncState *fs, OpCode o, int a, int b, int c, int k) {
}
-#define codeABsC(fs,o,a,b,c,k) luaK_codeABCk(fs,o,a,b,((c) + MAXARG_sC),k)
+#define codeABsC(fs,o,a,b,c,k) luaK_codeABCk(fs,o,a,b,((c) + OFFSET_sC),k)
@@ -378,7 +378,7 @@ int luaK_codeABx (FuncState *fs, OpCode o, int a, unsigned int bc) {
** Format and emit an 'iAsBx' instruction.
*/
int luaK_codeAsBx (FuncState *fs, OpCode o, int a, int bc) {
- unsigned int b = bc + MAXARG_sBx;
+ unsigned int b = bc + OFFSET_sBx;
lua_assert(getOpMode(o) == iAsBx);
lua_assert(a <= MAXARG_A && b <= MAXARG_Bx);
return luaK_code(fs, CREATE_ABx(o, a, b));
@@ -389,7 +389,7 @@ int luaK_codeAsBx (FuncState *fs, OpCode o, int a, int bc) {
** Format and emit an 'isJ' instruction.
*/
static int codesJ (FuncState *fs, OpCode o, int sj, int k) {
- unsigned int j = sj + MAXARG_sJ;
+ unsigned int j = sj + OFFSET_sJ;
lua_assert(getOpMode(o) == isJ);
lua_assert(j <= MAXARG_sJ && (k & ~1) == 0);
return luaK_code(fs, CREATE_sJ(o, j, k));
@@ -582,8 +582,26 @@ static int nilK (FuncState *fs) {
}
+/*
+** Check whether 'i' can be stored in an 'sC' operand.
+** Equivalent to (0 <= i + OFFSET_sC && i + OFFSET_sC <= MAXARG_C)
+** but without risk of overflows in the addition.
+*/
+static int fitsC (lua_Integer i) {
+ return (-OFFSET_sC <= i && i <= MAXARG_C - OFFSET_sC);
+}
+
+
+/*
+** Check whether 'i' can be stored in an 'sBx' operand.
+*/
+static int fitsBx (lua_Integer i) {
+ return (-OFFSET_sBx <= i && i <= MAXARG_Bx - OFFSET_sBx);
+}
+
+
void luaK_int (FuncState *fs, int reg, lua_Integer i) {
- if (l_castS2U(i) + MAXARG_sBx <= l_castS2U(MAXARG_Bx))
+ if (fitsBx(i))
luaK_codeAsBx(fs, OP_LOADI, reg, cast_int(i));
else
luaK_codek(fs, reg, luaK_intK(fs, i));
@@ -593,8 +611,7 @@ void luaK_int (FuncState *fs, int reg, lua_Integer i) {
static int floatI (lua_Number f, lua_Integer *fi) {
TValue v;
setfltvalue(&v, f);
- return (luaV_flttointeger(&v, fi, 0) &&
- l_castS2U(*fi) + MAXARG_sBx <= l_castS2U(MAXARG_Bx));
+ return (luaV_flttointeger(&v, fi, 0) && fitsBx(*fi));
}
@@ -1089,8 +1106,7 @@ static int isCint (expdesc *e) {
** proper range to fit in register sC
*/
static int isSCint (expdesc *e) {
- return (e->k == VKINT && !hasjumps(e) &&
- l_castS2U(e->u.ival + MAXARG_sC) <= l_castS2U(MAXARG_C));
+ return (e->k == VKINT && !hasjumps(e) && fitsC(e->u.ival));
}
@@ -1103,8 +1119,12 @@ static int isSCnumber (expdesc *e, lua_Integer *i) {
*i = e->u.ival;
else if (!(e->k == VKFLT && floatI(e->u.nval, i)))
return 0; /* not a number */
- *i += MAXARG_sC;
- return (!hasjumps(e) && l_castS2U(*i) <= l_castS2U(MAXARG_C));
+ if (!hasjumps(e) && fitsC(*i)) {
+ *i += OFFSET_sC;
+ return 1;
+ }
+ else
+ return 0;
}
diff --git a/lopcodes.h b/lopcodes.h
@@ -1,5 +1,5 @@
/*
-** $Id: lopcodes.h,v 1.177 2017/12/13 18:32:09 roberto Exp roberto $
+** $Id: lopcodes.h,v 1.178 2017/12/15 18:35:22 roberto Exp roberto $
** Opcodes for Lua virtual machine
** See Copyright Notice in lua.h
*/
@@ -62,13 +62,14 @@ enum OpMode {iABC, iABx, iAsBx, iAx, isJ}; /* basic instruction formats */
** so they must fit in LUAI_BITSINT-1 bits (-1 for sign)
*/
#if SIZE_Bx < LUAI_BITSINT-1
-#define MAXARG_Bx ((1<<SIZE_Bx)-1)
-#define MAXARG_sBx (MAXARG_Bx>>1) /* 'sBx' is signed */
+#define MAXARG_Bx ((1<<SIZE_Bx)-1)
#else
-#define MAXARG_Bx MAX_INT
-#define MAXARG_sBx MAX_INT
+#define MAXARG_Bx MAX_INT
#endif
+#define OFFSET_sBx (MAXARG_Bx>>1) /* 'sBx' is signed */
+
+
#if SIZE_Ax < LUAI_BITSINT-1
#define MAXARG_Ax ((1<<SIZE_Ax)-1)
#else
@@ -76,16 +77,18 @@ enum OpMode {iABC, iABx, iAsBx, iAx, isJ}; /* basic instruction formats */
#endif
#if SIZE_sJ < LUAI_BITSINT-1
-#define MAXARG_sJ ((1 << (SIZE_sJ - 1)) - 1)
+#define MAXARG_sJ ((1 << SIZE_sJ) - 1)
#else
#define MAXARG_sJ MAX_INT
#endif
+#define OFFSET_sJ (MAXARG_sJ >> 1)
+
#define MAXARG_A ((1<<SIZE_A)-1)
#define MAXARG_B ((1<<SIZE_B)-1)
#define MAXARG_C ((1<<SIZE_C)-1)
-#define MAXARG_sC (MAXARG_C >> 1)
+#define OFFSET_sC (MAXARG_C >> 1)
#define MAXARG_Cx ((1<<(SIZE_C + 1))-1)
@@ -114,11 +117,11 @@ enum OpMode {iABC, iABx, iAsBx, iAx, isJ}; /* basic instruction formats */
#define SETARG_A(i,v) setarg(i, v, POS_A, SIZE_A)
#define GETARG_B(i) check_exp(checkopm(i, iABC), getarg(i, POS_B, SIZE_B))
-#define GETARG_sB(i) (GETARG_B(i) - MAXARG_sC)
+#define GETARG_sB(i) (GETARG_B(i) - OFFSET_sC)
#define SETARG_B(i,v) setarg(i, v, POS_B, SIZE_B)
#define GETARG_C(i) check_exp(checkopm(i, iABC), getarg(i, POS_C, SIZE_C))
-#define GETARG_sC(i) (GETARG_C(i) - MAXARG_sC)
+#define GETARG_sC(i) (GETARG_C(i) - OFFSET_sC)
#define SETARG_C(i,v) setarg(i, v, POS_C, SIZE_C)
#define TESTARG_k(i) (cast(int, ((i) & (1u << POS_k))))
@@ -132,13 +135,13 @@ enum OpMode {iABC, iABx, iAsBx, iAx, isJ}; /* basic instruction formats */
#define SETARG_Ax(i,v) setarg(i, v, POS_Ax, SIZE_Ax)
#define GETARG_sBx(i) \
- check_exp(checkopm(i, iAsBx), getarg(i, POS_Bx, SIZE_Bx) - MAXARG_sBx)
-#define SETARG_sBx(i,b) SETARG_Bx((i),cast(unsigned int, (b)+MAXARG_sBx))
+ check_exp(checkopm(i, iAsBx), getarg(i, POS_Bx, SIZE_Bx) - OFFSET_sBx)
+#define SETARG_sBx(i,b) SETARG_Bx((i),cast(unsigned int, (b)+OFFSET_sBx))
#define GETARG_sJ(i) \
- check_exp(checkopm(i, isJ), getarg(i, POS_sJ, SIZE_sJ) - MAXARG_sJ)
+ check_exp(checkopm(i, isJ), getarg(i, POS_sJ, SIZE_sJ) - OFFSET_sJ)
#define SETARG_sJ(i,j) \
- setarg(i, cast(unsigned int, (j)+MAXARG_sJ), POS_sJ, SIZE_sJ)
+ setarg(i, cast(unsigned int, (j)+OFFSET_sJ), POS_sJ, SIZE_sJ)
#define CREATE_ABCk(o,a,b,c,k) ((cast(Instruction, o)<<POS_OP) \
diff --git a/ltests.c b/ltests.c
@@ -1,5 +1,5 @@
/*
-** $Id: ltests.c,v 2.235 2017/12/08 15:19:13 roberto Exp roberto $
+** $Id: ltests.c,v 2.236 2017/12/11 18:55:31 roberto Exp roberto $
** Internal Module for Debugging of the Lua Implementation
** See Copyright Notice in lua.h
*/
@@ -665,7 +665,7 @@ static int get_limits (lua_State *L) {
setnameval(L, "BITS_INT", LUAI_BITSINT);
setnameval(L, "MAXARG_Ax", MAXARG_Ax);
setnameval(L, "MAXARG_Bx", MAXARG_Bx);
- setnameval(L, "MAXARG_sBx", MAXARG_sBx);
+ setnameval(L, "OFFSET_sBx", OFFSET_sBx);
setnameval(L, "BITS_INT", LUAI_BITSINT);
setnameval(L, "LFPF", LFIELDS_PER_FLUSH);
setnameval(L, "NUM_OPCODES", NUM_OPCODES);
