bool asCParser::IsDataType(int tokenType)
{
if( tokenType == ttIdentifier ||
IsRealType(tokenType) )
return true;
return false;
}
asCScriptNode *asCParser::ParseRealType()
{
asCScriptNode *node = new asCScriptNode(snDataType);
sToken t1;
GetToken(&t1);
if( !IsRealType(t1.type) )
{
Error(TXT_EXPECTED_DATA_TYPE, &t1);
return node;
}
node->SetToken(&t1);
node->UpdateSourcePos(t1.pos, t1.length);
return node;
}
bool asCParser::IsFunctionCall()
{
sToken t1, t2;
GetToken(&t1);
if( t1.type != ttIdentifier && !IsRealType(t1.type) )
{
RewindTo(&t1);
return false;
}
// The name can be followed by handle and closed array brackets
GetToken(&t2);
while( t2.type == ttHandle || t2.type == ttOpenBracket )
{
if( t2.type == ttOpenBracket )
{
GetToken(&t2);
if( t2.type != ttCloseBracket )
{
RewindTo(&t1);
return false;
}
}
GetToken(&t2);
}
if( t2.type == ttOpenParanthesis )
{
RewindTo(&t1);
return true;
}
RewindTo(&t1);
return false;
}
asCScriptNode *asCParser::ParseExprValue()
{
asCScriptNode *node = new asCScriptNode(snExprValue);
sToken t1;
GetToken(&t1);
RewindTo(&t1);
if( t1.type == ttIdentifier || IsRealType(t1.type) )
{
if( IsFunctionCall() )
node->AddChildLast(ParseFunctionCall());
else
node->AddChildLast(ParseIdentifier());
}
else if( t1.type == ttCast )
node->AddChildLast(ParseCast());
else if( IsConstant(t1.type) )
node->AddChildLast(ParseConstant());
else if( t1.type == ttOpenParanthesis )
{
GetToken(&t1);
node->UpdateSourcePos(t1.pos, t1.length);
node->AddChildLast(ParseAssignment());
if( isSyntaxError ) return node;
GetToken(&t1);
if( t1.type != ttCloseParanthesis )
Error(ExpectedToken(")").AddressOf(), &t1);
node->UpdateSourcePos(t1.pos, t1.length);
}
else
Error(TXT_EXPECTED_EXPRESSION_VALUE, &t1);
return node;
}
/**
* Perform algebraic simplification and strenth reduction
*/
Symbol Simplify(Type ty, int opcode, Symbol src1, Symbol src2)
{
VariableSymbol t;
Symbol p1, p2;
int c1, c2;
if (IsRealType(ty))
goto add_value;
if (src2 == NULL || (src2->kind != SK_Constant && opcode != SUB))
goto add_value;
switch (opcode)
{
case ADD:
// a + 0 = a
if (src2->val.i[0] == 0)
return src1;
// a + c1 + c2 = a + (c1 + c2)
// a - c1 + c2 = a + (-c1 + c2)
p1 = src1; c1 = 0;
if (src1->kind == SK_Temp)
{
t = AsVar(src1);
if (t->def->src2 && t->def->src2->kind == SK_Constant &&
(t->def->op == ADD || t->def->op == SUB))
{
p1 = t->def->src1;
c1 = (t->def->op == ADD ? 1 : -1) * t->def->src2->val.i[0];
}
}
if (c1 != 0)
{
src1 = p1;
src2 = IntConstant(c1 + src2->val.i[0]);
}
break;
case SUB:
// a - 0 = a
if (src2->kind == SK_Constant && src2->val.i[0] == 0)
return src1;
// put source operand into v + c format (v maybe NULL, c maybe 0)
p1 = src1; c1 = 0;
if (src1->kind == SK_Temp)
{
t = AsVar(src1);
if (t->def->src2 && t->def->src2->kind == SK_Constant &&
(t->def->op == ADD || t->def->op == SUB))
{
p1 = t->def->src1;
c1 = (t->def->op == ADD ? 1 : -1) * t->def->src2->val.i[0];
}
}
else if (src1->kind == SK_Constant)
{
p1 = NULL;
c1 = src1->val.i[0];
}
p2 = src2; c2 = 0;
if (src2->kind == SK_Temp)
{
t = AsVar(src2);
if (t->def->src2 && t->def->src2->kind == SK_Constant &&
(t->def->op == ADD || t->def->op == SUB))
{
p2 = t->def->src1;
c2 = (t->def->op == ADD ? 1 : -1) * t->def->src2->val.i[0];
}
}
else if (src2->kind == SK_Constant)
{
p2 = NULL;
c2 = src2->val.i[0];
}
if (p1 == p2)
{
// (a + c1) - (a + c2) = c1 - c2
return IntConstant(c1 - c2);
}
else if (p1 == NULL)
{
// c1 - (a + c2) = (c1 - c2) - a
src1 = IntConstant(c1 - c2);
src2 = p2;
}
else if (p2 == NULL)
{
// (a + c1) - c2 = a + (c1 - c2)
src1 = p1;
opcode = ADD;
src2 = IntConstant(c1 - c2);
}
break;
case MUL:
case DIV:
// a * 1 = a; a / 1 = a;
if (src2->val.i[0] == 1)
return src1;
// a * 2 power of n = a >> n
c1 = Power2(src2->val.i[0]);
if (c1 != 0)
{
src2 = IntConstant(c1);
opcode = opcode == MUL ? LSH : RSH;
}
break;
case MOD:
// a % 1 = 0
if (src2->val.i[0] == 1)
return IntConstant(0);
// a % 2 power of n = a & (2 power of n - 1)
c1 = Power2(src2->val.i[0]);
if (c1 != 0)
{
src2 = IntConstant(src2->val.i[0] - 1);
opcode = BAND;
}
break;
case LSH:
case RSH:
// a >> 0 = a << 0 = a
if (src2->val.i[0] == 0)
return src1;
break;
case BOR:
// a | 0 = a; a | -1 = -1
if (src2->val.i[0] == 0)
return src1;
if (src2->val.i[0] == -1)
return src2;
break;
case BXOR:
// a ^ 0 = a
if (src2->val.i[0] == 0)
return src1;
break;
case BAND:
// a & 0 = 0, a & -1 = a
if (src2->val.i[0] == 0)
return IntConstant(0);
if (src2->val.i[0] == -1)
return src1;
break;
default:
break;
}
add_value:
return TryAddValue(ty, opcode, src1, src2);
}
/* 算数优化 */
Symbol Simplify (Type ty, int opcode, Symbol src1, Symbol src2)
{
VariableSymbol t;
Symbol p1, p2;
int c1, c2;
/* 浮点 */
if (IsRealType (ty))
goto add_value;
if (src2 == NULL || (src2->kind != SK_Constant && opcode != SUB))
goto add_value;
/* 以下是 加, 减, 乘, 除, 取余, 左移, 右移, 按位操作的优化 */
switch (opcode) {
case ADD: {
/* a + 0 = a */
if (src2->val.i[0] == 0)
return src1;
/* a + c1 + c2 = a + (c1 + c2) */
/* a - c1 + c2 = a + (-c1 + c2) */
p1 = src1; c1 = 0;
if (src1->kind == SK_Temp) {
t = AsVar(src1);
if (t->def->src2 && t->def->src2->kind == SK_Constant &&
(t->def->op == ADD || t->def->op == SUB)) {
p1 = t->def->src1;
c1 = (t->def->op == ADD ? 1 : -1) * t->def->src2->val.i[0];
}
}
if (c1 != 0) {
src1 = p1;
/* 合并c1, c2 */
src2 = IntConstant (c1 + src2->val.i[0]);
}
}break;
case SUB: {
/* a - 0 = a */
if (src2->kind == SK_Constant && src2->val.i[0] == 0)
return src1;
// put source operand into v + c format (v maybe NULL, c maybe 0)
p1 = src1; c1 = 0;
if (src1->kind == SK_Temp) {
t = AsVar(src1);
if (t->def->src2 && t->def->src2->kind == SK_Constant &&
(t->def->op == ADD || t->def->op == SUB)) {
p1 = t->def->src1;
c1 = (t->def->op == ADD ? 1 : -1) * t->def->src2->val.i[0];
}
} else if (src1->kind == SK_Constant) {
p1 = NULL;
c1 = src1->val.i[0];
}
p2 = src2; c2 = 0;
if (src2->kind == SK_Temp) {
t = AsVar(src2);
if (t->def->src2 && t->def->src2->kind == SK_Constant &&
(t->def->op == ADD || t->def->op == SUB)) {
p2 = t->def->src1;
c2 = (t->def->op == ADD ? 1 : -1) * t->def->src2->val.i[0];
}
} else if (src2->kind == SK_Constant) {
p2 = NULL;
c2 = src2->val.i[0];
}
if (p1 == p2) {
/* (a + c1) - (a + c2) = c1 - c2 */
return IntConstant (c1 - c2);
} else if (p1 == NULL) {
/* c1 - (a + c2) = (c1 - c2) - a */
src1 = IntConstant (c1 - c2);
src2 = p2;
} else if (p2 == NULL) {
/* (a + c1) - c2 = a + (c1 - c2) */
src1 = p1;
opcode = ADD;
src2 = IntConstant(c1 - c2);
}
}break;
case MUL: case DIV: {
/* a * 1 = a; a / 1 = a; */
if (src2->val.i[0] == 1)
return src1;
/* a * 2 power of n = a >> n */
c1 = Power2 (src2->val.i[0]);
if (c1 != 0) {
/* 转换乘除为位移操作 */
src2 = IntConstant (c1);
opcode = opcode == MUL ? LSH : RSH;
}
}break;
case MOD: {
/* a % 1 = 0 */
if (src2->val.i[0] == 1)
return IntConstant (0);
/* a % 2 power of n = a & (2 power of n - 1) */
c1 = Power2 (src2->val.i[0]);
if (c1 != 0) {
src2 = IntConstant (src2->val.i[0] - 1);
opcode = BAND;
}
}break;
case LSH: case RSH: {
/* a >> 0 = a << 0 = a */
if (src2->val.i[0] == 0)
return src1;
}break;
case BOR: {
/* a | 0 = a; a | -1 = -1 */
if (src2->val.i[0] == 0)
return src1;
if (src2->val.i[0] == -1)
return src2;
}break;
case BXOR: {
/* a ^ 0 = a */
if (src2->val.i[0] == 0)
return src1;
}break;
case BAND: {
/* a & 0 = 0, a & -1 = a */
if (src2->val.i[0] == 0)
return IntConstant(0);
if (src2->val.i[0] == -1)
return src1;
}break;
default: break;
}
add_value:
/* 构造值添加到符号表中,并返回 */
return TryAddValue (ty, opcode, src1, src2);
}
