scc

Simple C99 Compiler
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commit 5763a15c686c2197d369ccf742718eb4a9f02271
parent 839b28355e9bc831c2a05947925111af79a5bc0f
Author: Roberto E. Vargas Caballero <k0ga@shike2.com>
Date:   Tue, 22 Apr 2014 07:39:07 +0200

Rewrite unary()

unary() code was ugly, and the inner switch was the same of the
first, so the best solution for this kind of cases is to use a pointer
function.

Diffstat:
expr.c | 130++++++++++++++++++++++++++++++++++++++++----------------------------------------
1 file changed, 65 insertions(+), 65 deletions(-)

diff --git a/expr.c b/expr.c @@ -68,6 +68,14 @@ integerop(char op, Node *np1, Node *np2) } static Node * +integeruop(char op, Node *np) +{ + if (np->typeop != INT) + error("unary operator requires integer operand"); + return unarycode(op, np->type, np); +} + +static Node * addr2ptr(Node *np) { Type *tp; @@ -345,6 +353,52 @@ error: error(err); } +static Node * +address(char op, Node *np) +{ + char *err; + + if (!np->b.lvalue) + goto no_lvalue; + if (np->b.symbol && np->u.sym->s.isregister) + goto reg_address; + return unarycode(op, mktype(np->type, PTR, NULL, 0), np); + +no_lvalue: + err = "lvalue required in unary expression"; + goto error; +reg_address: + err = "address of register variable '%s' requested"; +error: + error(err); +} + +static Node * +content(char op, Node *np) +{ + switch (np->typeop) { + case ARY: case FTN: + np = addr2ptr(np); + case PTR: + return unarycode(op, np->utype->type, np); + default: + error("invalid argument of unary '*'"); + } +} + +static Node * +negation(char op, Node *np) +{ + switch (np->typeop) { + case FTN: case ARY: + np = addr2ptr(np); + case INT: case FLOAT: case PTR: + return exp2cond(np, 1); + default: + error("invalid argument of unary '!'"); + } +} + /************************************************************* * grammar functions * *************************************************************/ @@ -410,10 +464,10 @@ static Node *cast(void); static Node * unary(void) { - register Node *np; + register Node *(*fun)(char, Node *); + register char op; Type *tp; - char op, *err; - uint8_t t; + char *err; switch (yytoken) { case SIZEOF: @@ -431,71 +485,17 @@ unary(void) op = (yytoken == INC) ? OINC : ODEC; next(); return incdec(unary(), op); - case '!': case '&': case '*': case '+': case '~': case '-': - op = yytoken; - next(); - np = cast(); - tp = UNQUAL(np->type); - t = tp->op; - switch (op) { - case '*': - op = OPTR; - switch (t) { - case ARY: case FTN: - np = addr2ptr(np); - case PTR: - tp = tp->type; - break; - default: - goto bad_operand; - } - break; - case '&': - op = OADDR; - if (!np->b.lvalue) - goto no_lvalue; - if (np->b.symbol && np->u.sym->s.isregister) - goto reg_address; - tp = mktype(tp, PTR, NULL, 0); - break; - case '!': - switch (t) { - case FTN: case ARY: - np = addr2ptr(np); - case INT: case FLOAT: case PTR: - return exp2cond(np, 1); - break; - default: - goto bad_operand; - } - case '+': - if (t != INT) - goto bad_operand; - return np; - case '~': - op = OCPL; - if (t != INT) - goto bad_operand; - break; - case '-': - op = ONEG; - if (t != INT && t != FLOAT) - goto bad_operand; - } - return unarycode(op, tp, np); + case '!': op = 0; fun = negation; break; + case '+': op = OADD; fun = integeruop; break; + case '-': op = OSUB; fun = integeruop; break; + case '~': op = ONEG; fun = integeruop; break; + case '&': op = OADDR; fun = address; break; + case '*': op = OPTR; fun = content; break; default: return postfix(); } -no_lvalue: - err = "lvalue required in unary expression"; - goto error; -reg_address: - err = "address of register variable '%s' requested"; - goto error; -bad_operand: - err = "bad operand in unary expression"; -error: - error(err, yytext); + next(); + return (*fun)(op, cast()); } static Node *