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Precalculate some expressions

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git-svn-id: svn://svn.cc65.org/cc65/trunk@2651 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
cuz 2003-11-12 16:40:26 +00:00
parent 7c5a400e01
commit 980f5b598f
1 changed files with 153 additions and 28 deletions
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181
src/ca65/expr.c
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@ -189,6 +189,35 @@ int IsWordRange (long Val)
static int IsEasyConst (const ExprNode* E, long* Val)
/* Do some light checking if the given node is a constant. Don't care if E is
* a complex expression. If E is a constant, return true and place its value
* into Val, provided that Val is not NULL.
*/
{
/* Resolve symbols, follow symbol chains */
while (E->Op == EXPR_SYMBOL) {
E = SymResolve (E->V.Sym);
if (E == 0) {
/* Could not resolve */
return 0;
}
}
/* Symbols resolved, check for a literal */
if (E->Op == EXPR_LITERAL) {
if (Val) {
*Val = E->V.Val;
}
return 1;
}
/* Not found to be a const according to our tests */
return 0;
}
static int FuncBlank (void)
/* Handle the .BLANK builtin function */
{
@ -503,8 +532,10 @@ static ExprNode* Function (int (*F) (void))
static ExprNode* Factor (void)
{
ExprNode* L;
ExprNode* N;
SymEntry* S;
long Val;
switch (Tok) {
@ -540,14 +571,26 @@ static ExprNode* Factor (void)
case TOK_MINUS:
NextTok ();
N = NewExprNode (EXPR_UNARY_MINUS);
N->Left = Factor ();
L = Factor ();
if (IsEasyConst (L, &Val)) {
FreeExpr (L);
N = GenLiteralExpr (-Val);
} else {
N = NewExprNode (EXPR_UNARY_MINUS);
N->Left = L;
}
break;
case TOK_NOT:
NextTok ();
N = NewExprNode (EXPR_NOT);
N->Left = Factor ();
L = Factor ();
if (IsEasyConst (L, &Val)) {
FreeExpr (L);
N = GenLiteralExpr (~Val);
} else {
N = NewExprNode (EXPR_NOT);
N->Left = L;
}
break;
case TOK_STAR:
@ -558,20 +601,38 @@ static ExprNode* Factor (void)
case TOK_LT:
NextTok ();
N = NewExprNode (EXPR_BYTE0);
N->Left = Factor ();
L = Factor ();
if (IsEasyConst (L, &Val)) {
FreeExpr (L);
N = GenLiteralExpr (Val & 0xFF);
} else {
N = NewExprNode (EXPR_BYTE0);
N->Left = L;
}
break;
case TOK_GT:
NextTok ();
N = NewExprNode (EXPR_BYTE1);
N->Left = Factor ();
L = Factor ();
if (IsEasyConst (L, &Val)) {
FreeExpr (L);
N = GenLiteralExpr ((Val >> 8) & 0xFF);
} else {
N = NewExprNode (EXPR_BYTE1);
N->Left = L;
}
break;
case TOK_BANK:
NextTok ();
N = NewExprNode (EXPR_BYTE2);
N->Left = Factor ();
L = Factor ();
if (IsEasyConst (L, &Val)) {
FreeExpr (L);
N = GenLiteralExpr ((Val >> 16) & 0xFF);
} else {
N = NewExprNode (EXPR_BYTE2);
N->Left = L;
}
break;
case TOK_LPAREN:
@ -627,7 +688,6 @@ static ExprNode* Factor (void)
NextTok ();
break;
case TOK_XMATCH:
N = Function (FuncXMatch);
break;
@ -658,25 +718,90 @@ static ExprNode* Term (void)
Tok == TOK_AND || Tok == TOK_XOR || Tok == TOK_SHL ||
Tok == TOK_SHR) {
/* Create the new node */
ExprNode* Left = Root;
switch (Tok) {
case TOK_MUL: Root = NewExprNode (EXPR_MUL); break;
case TOK_DIV: Root = NewExprNode (EXPR_DIV); break;
case TOK_MOD: Root = NewExprNode (EXPR_MOD); break;
case TOK_AND: Root = NewExprNode (EXPR_AND); break;
case TOK_XOR: Root = NewExprNode (EXPR_XOR); break;
case TOK_SHL: Root = NewExprNode (EXPR_SHL); break;
case TOK_SHR: Root = NewExprNode (EXPR_SHR); break;
default: Internal ("Invalid token");
}
Root->Left = Left;
long LVal, RVal, Val;
ExprNode* Left;
ExprNode* Right;
/* Skip the operator token */
NextTok ();
/* Remember the token and skip it */
enum Token T = Tok;
NextTok ();
/* Parse the right hand side */
Root->Right = Factor ();
/* Move root to left side and read the right side */
Left = Root;
Right = Factor ();
/* If both expressions are constant, we can evaluate the term */
if (IsEasyConst (Left, &LVal) && IsEasyConst (Right, &RVal)) {
switch (T) {
case TOK_MUL:
Val = LVal * RVal;
break;
case TOK_DIV:
if (RVal == 0) {
Error ("Division by zero");
Val = 1;
} else {
Val = LVal / RVal;
}
break;
case TOK_MOD:
if (RVal == 0) {
Error ("Modulo operation with zero");
Val = 1;
} else {
Val = LVal % RVal;
}
break;
case TOK_AND:
Val = LVal & RVal;
break;
case TOK_XOR:
Val = LVal ^ RVal;
break;
case TOK_SHL:
Val = shl_l (LVal, RVal);
break;
case TOK_SHR:
Val = shr_l (LVal, RVal);
break;
default:
Internal ("Invalid token");
}
/* Generate a literal expression and delete the old left and
* right sides.
*/
FreeExpr (Left);
FreeExpr (Right);
Root = GenLiteralExpr (Val);
} else {
/* Generate an expression tree */
unsigned char Op;
switch (T) {
case TOK_MUL: Op = EXPR_MUL; break;
case TOK_DIV: Op = EXPR_DIV; break;
case TOK_MOD: Op = EXPR_MOD; break;
case TOK_AND: Op = EXPR_AND; break;
case TOK_XOR: Op = EXPR_XOR; break;
case TOK_SHL: Op = EXPR_SHL; break;
case TOK_SHR: Op = EXPR_SHR; break;
default: Internal ("Invalid token");
}
Root = NewExprNode (Op);
Root->Left = Left;
Root->Right = Right;
}
}