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jumps are relative to next instruction

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This commit is contained in:
Roberto Ierusalimschy
1997-10-06 12:51:11 -02:00
parent 28d47a0aaa
commit f6a9cc9a67
3 changed files with 132 additions and 125 deletions
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68
lua.stx
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@@ -1,6 +1,6 @@
%{
/*
** $Id: lua.stx,v 1.6 1997/09/26 15:02:26 roberto Exp roberto $
** $Id: lua.stx,v 1.7 1997/10/01 20:05:34 roberto Exp roberto $
** Syntax analizer and code generator
** See Copyright Notice in lua.h
*/
@@ -135,31 +135,6 @@ static void code_word (int n)
}
static int fix_opcode (int pc, OpCode op, int n)
{
if (n <= 255) {
currState->f->code[pc] = op;
currState->f->code[pc+1] = n;
return 0;
}
else {
check_pc(1); /* open space */
movecode_up(pc+1, pc, currState->pc-pc);
currState->pc++;
currState->f->code[pc] = op+1; /* opcode must be word variant */
code_word_at(pc+1, n);
return 1;
}
}
static int fix_jump (int pc, OpCode op, int n)
{
n -= pc+1; /* jump is relative to position following jump opcode */
if (n > 255) n++; /* jump must be 1 bigger */
return fix_opcode(pc, op, n);
}
static void deltastack (int delta)
{
currState->stacksize += delta;
@@ -501,6 +476,39 @@ static int lua_codestore (int i, int left)
}
static int fix_opcode (int pc, OpCode op, int n)
{
if (n <= 255) {
currState->f->code[pc] = op;
currState->f->code[pc+1] = n;
return 0;
}
else {
check_pc(1); /* open space */
movecode_up(pc+1, pc, currState->pc-pc);
currState->pc++;
currState->f->code[pc] = op+1; /* opcode must be word variant */
code_word_at(pc+1, n);
return 1;
}
}
static int fix_jump (int pc, OpCode op, int n)
{
/* jump is relative to position following jump instruction */
return fix_opcode(pc, op, n-(pc+JMPSIZE));
}
static void fix_upjmp (OpCode op, int pos)
{
int delta = currState->pc+JMPSIZE - pos; /* jump is relative */
if (delta > 255) delta++;
code_opborw(op, delta, 0);
}
static void codeIf (int thenAdd, int elseAdd)
{
int elseinit = elseAdd+JMPSIZE;
@@ -516,7 +524,7 @@ static void codeIf (int thenAdd, int elseAdd)
static void code_shortcircuit (OpCode op, int pos)
{
int dist = currState->pc - (pos+1);
int dist = currState->pc - (pos+JMPSIZE);
if (dist > 255)
luaY_error("and/or expression too long");
currState->f->code[pos] = op;
@@ -578,7 +586,6 @@ static void init_func (void)
}
static TProtoFunc *close_func (void)
{
TProtoFunc *f = currState->f;
@@ -681,12 +688,13 @@ stat : IF cond THEN block SaveWord elsepart END
&currState->f->code[$2], expsize);
movecode_down($2, $3, currState->pc-$2);
newpos += fix_jump($2, JMPB, currState->pc-expsize);
code_opborw(IFTUPJMPB, currState->pc+1 - newpos, 0);
fix_upjmp(IFTUPJMPB, newpos);
}}
| REPEAT GetPC block UNTIL expr1
{
code_opborw(IFFUPJMPB, currState->pc+1 - $2, -1);
fix_upjmp(IFFUPJMPB, $2);
deltastack(-1); /* pops condition */
}
| varlist1 '=' exprlist1