/* * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands. * See the copyright notice in the ACK home directory, in the file "Copyright". */ /* $Header$ */ /* CODE FOR THE INITIALISATION OF GLOBAL VARIABLES */ #include "nofloat.h" #include #include "debug.h" #include #include "nobitfield.h" #include "arith.h" #include "align.h" #include "label.h" #include "expr.h" #include "type.h" #include "struct.h" #include "field.h" #include "assert.h" #include "Lpars.h" #include "class.h" #include "sizes.h" #include "idf.h" #include "level.h" #include "def.h" #define con_nullbyte() C_con_ucon("0", (arith)1) char *symbol2str(); char *long2str(); char *strncpy(); struct expr *do_array(), *do_struct(), *IVAL(); extern char options[]; /* do_ival() performs the initialisation of a global variable of type tp with the initialisation expression expr by calling IVAL(). Guided by type tp, the expression is evaluated. */ do_ival(tpp, ex) struct type **tpp; struct expr *ex; { if (IVAL(tpp, ex) != 0) too_many_initialisers(ex); } /* IVAL() recursively guides the initialisation expression through the different routines for the different types of initialisation: - array initialisation - struct initialisation - fundamental type initialisation Upto now, the initialisation of a union is not allowed! An initialisation expression tree consists of normal expressions which can be joined together by ',' nodes, which operator acts like the lisp function "cons" to build lists. IVAL() returns a pointer to the remaining expression tree. */ struct expr * IVAL(tpp, ex) struct type **tpp; /* type of global variable */ register struct expr *ex; /* initialiser expression */ { register struct type *tp = *tpp; switch (tp->tp_fund) { case ARRAY: /* array initialisation */ if (valid_type(tp->tp_up, "array element") == 0) return 0; if (ISCOMMA(ex)) /* list of initialisation expressions */ return do_array(ex, tpp); if (tp->tp_up->tp_fund == CHAR && ex->ex_class == String) /* initialisation like char s[] = "I am a string" */ ch_array(tpp, ex); else /* " int i[24] = 12;" */ check_and_pad(ex, tpp); break; case STRUCT: /* struct initialisation */ if (valid_type(tp, "struct") == 0) return 0; if (ISCOMMA(ex)) /* list of initialisation expressions */ return do_struct(ex, tp); check_and_pad(ex, tpp); /* "struct foo f = 12;" */ break; case UNION: error("union initialisation not allowed"); break; case ERRONEOUS: break; default: /* fundamental type */ if (ISCOMMA(ex)) { /* " int i = {12};" */ if (IVAL(tpp, ex->OP_LEFT) != 0) too_many_initialisers(ex); /* return remainings of the list for the other members of the aggregate, if this item belongs to an aggregate. */ return ex->OP_RIGHT; } check_ival(ex, tp); /* "int i = 12;" */ break; } return 0; } /* do_array() initialises the members of an array described by type tp with the expressions in expr. Two important cases: - the number of members is known - the number of members is not known In the latter case, do_array() digests the whole expression tree it is given. In the former case, do_array() eats as many members from the expression tree as are needed for the array. If there are not sufficient members for the array, the remaining members are padded with zeroes */ struct expr * do_array(ex, tpp) register struct expr *ex; struct type **tpp; { register struct type *tp = *tpp; register arith elem_count; ASSERT(tp->tp_fund == ARRAY && ISCOMMA(ex)); /* the following test catches initialisations like char c[] = {"just a string"}; or char d[] = {{"just another string"}}; The use of the brackets causes this problem. Note: although the implementation of such initialisations is completely foolish, we did it!! (no applause, thank you) */ if (tp->tp_up->tp_fund == CHAR) { register struct expr *f = ex->OP_LEFT, *g = NILEXPR; while (ISCOMMA(f)) { /* eat the brackets!!! */ g = f; f = f->OP_LEFT; } if (f->ex_class == String) { /* hallelujah, it's a string! */ ch_array(tpp, f); return g ? g->OP_RIGHT : ex->OP_RIGHT; } /* else: just go on with the next part of this function */ if (g != 0) ex = g; } if (tp->tp_size == (arith)-1) { /* declared with unknown size: [] */ for (elem_count = 0; ex; elem_count++) { /* eat whole initialisation expression */ if (ISCOMMA(ex->OP_LEFT)) { /* embraced member */ if (IVAL(&(tp->tp_up), ex->OP_LEFT) != 0) too_many_initialisers(ex); ex = ex->OP_RIGHT; } else { if (aggregate_type(tp->tp_up)) ex = IVAL(&(tp->tp_up), ex); else { check_ival(ex->OP_LEFT, tp->tp_up); ex = ex->OP_RIGHT; } } } /* set the proper size */ *tpp = construct_type(ARRAY, tp->tp_up, elem_count); } else { /* the number of members is already known */ arith dim = tp->tp_size / tp->tp_up->tp_size; for (elem_count = 0; elem_count < dim && ex; elem_count++) { if (ISCOMMA(ex->OP_LEFT)) { /* embraced member */ if (IVAL(&(tp->tp_up), ex->OP_LEFT) != 0) too_many_initialisers(ex); ex = ex->OP_RIGHT; } else { if (aggregate_type(tp->tp_up)) ex = IVAL(&(tp->tp_up), ex); else { check_ival(ex->OP_LEFT, tp->tp_up); ex = ex->OP_RIGHT; } } } if (ex && elem_count == dim) /* all the members are initialised but there remains a part of the expression tree which is returned */ return ex; if ((ex == 0) && elem_count < dim) /* the expression tree is completely absorbed but there are still members which must be initialised with zeroes */ do pad(tp->tp_up); while (++elem_count < dim); } return 0; } /* do_struct() initialises a struct of type tp with the expression expr. The main loop is just controlled by the definition of the selectors during which alignment is taken care of. */ struct expr * do_struct(ex, tp) register struct expr *ex; register struct type *tp; { register struct sdef *sd = tp->tp_sdef; arith bytes_upto_here = (arith)0; arith last_offset = (arith)-1; ASSERT(tp->tp_fund == STRUCT && ISCOMMA(ex)); /* as long as there are selectors and there is an initialiser.. */ while (sd && ex) { if (ISCOMMA(ex->OP_LEFT)) { /* embraced expression */ if (IVAL(&(sd->sd_type), ex->OP_LEFT) != 0) too_many_initialisers(ex); ex = ex->OP_RIGHT; } else { if (aggregate_type(sd->sd_type)) /* selector is an aggregate itself */ ex = IVAL(&(sd->sd_type), ex); else { #ifdef NOBITFIELD /* fundamental type, not embraced */ check_ival(ex->OP_LEFT, sd->sd_type); ex = ex->OP_RIGHT; #else if (is_anon_idf(sd->sd_idf)) /* a hole in the struct due to the use of ";:n;" in a struct definition. */ put_bf(sd->sd_type, (arith)0); else { /* fundamental type, not embraced */ check_ival(ex->OP_LEFT, sd->sd_type); ex = ex->OP_RIGHT; } #endif NOBITFIELD } } if (sd->sd_sdef) /* align upto the next selector boundary */ bytes_upto_here += zero_bytes(sd); if (last_offset != sd->sd_offset) { /* don't take the field-width more than once */ bytes_upto_here += size_of_type(sd->sd_type, "selector"); last_offset = sd->sd_offset; } sd = sd->sd_sdef; } /* perfect fit if (ex && (sd == 0)) holds */ if ((ex == 0) && (sd != 0)) { /* there are selectors left which must be padded with zeroes */ do { pad(sd->sd_type); /* take care of the alignment restrictions */ if (sd->sd_sdef) bytes_upto_here += zero_bytes(sd); /* no field thrown-outs here */ bytes_upto_here += size_of_type(sd->sd_type, "selector"); } while (sd = sd->sd_sdef); } /* keep on aligning... */ while (bytes_upto_here++ < tp->tp_size) con_nullbyte(); return ex; } /* check_and_pad() is given a simple initialisation expression where the type can be either a simple or an aggregate type. In the latter case, only the first member is initialised and the rest is zeroed. */ check_and_pad(ex, tpp) register struct expr *ex; struct type **tpp; { /* ex is of a fundamental type */ register struct type *tp = *tpp; if (tp->tp_fund == ARRAY) { if (valid_type(tp->tp_up, "array element") == 0) return; check_and_pad(ex, &(tp->tp_up)); /* first member */ if (tp->tp_size == (arith)-1) /* no size specified upto here: just set it to the size of one member. */ tp = *tpp = construct_type(ARRAY, tp->tp_up, (arith)1); else { register int dim = tp->tp_size / tp->tp_up->tp_size; /* pad remaining members with zeroes */ while (--dim > 0) pad(tp->tp_up); } } else if (tp->tp_fund == STRUCT) { register struct sdef *sd = tp->tp_sdef; if (valid_type(tp, "struct") == 0) return; check_and_pad(ex, &(sd->sd_type)); /* next selector is aligned by adding extra zeroes */ if (sd->sd_sdef) zero_bytes(sd); while (sd = sd->sd_sdef) { /* pad remaining selectors */ pad(sd->sd_type); if (sd->sd_sdef) zero_bytes(sd); } } else /* simple type */ check_ival(ex, tp); } /* pad() fills an element of type tp with zeroes. If the element is an aggregate, pad() is called recursively. */ pad(tp) register struct type *tp; { register arith sz = tp->tp_size; switch (tp->tp_fund) { case ARRAY: if (valid_type(tp->tp_up, "array element") == 0) return; break; case STRUCT: if (valid_type(tp, "struct") == 0) return; break; case UNION: if (valid_type(tp, "union") == 0) return; if (options['R']) { warning("initialisation of unions not allowed"); } break; #ifndef NOBITFIELD case FIELD: put_bf(tp, (arith)0); return; #endif NOBITFIELD case ERRONEOUS: return; } while (sz >= word_size) { C_con_cst((arith) 0); sz -= word_size; } while (sz) { C_con_icon("0", (arith) 1); sz--; } } /* check_ival() checks whether the initialisation of an element of a fundamental type is legal and, if so, performs the initialisation by directly generating the necessary code. No further comment is needed to explain the internal structure of this straightforward function. */ check_ival(expr, tp) register struct expr *expr; register struct type *tp; { /* The philosophy here is that ch7cast puts an explicit conversion node in front of the expression if the types are not compatible. In this case, the initialisation expression is no longer a constant. */ struct expr *ex = expr; switch (tp->tp_fund) { case CHAR: case SHORT: case INT: case LONG: case ENUM: case POINTER: ch7cast(&ex, '=', tp); expr = ex; #ifdef DEBUG print_expr("init-expr after cast", expr); #endif DEBUG if (!is_ld_cst(expr)) illegal_init_cst(expr); else if (expr->VL_CLASS == Const) con_int(expr); else if (expr->VL_CLASS == Name) { register struct idf *idf = expr->VL_IDF; if (idf->id_def->df_level >= L_LOCAL) illegal_init_cst(expr); else /* e.g., int f(); int p = f; */ if (idf->id_def->df_type->tp_fund == FUNCTION) C_con_pnam(idf->id_text); else /* e.g., int a; int *p = &a; */ C_con_dnam(idf->id_text, expr->VL_VALUE); } else { ASSERT(expr->VL_CLASS == Label); C_con_dlb(expr->VL_LBL, expr->VL_VALUE); } break; #ifndef NOFLOAT case FLOAT: case DOUBLE: ch7cast(&ex, '=', tp); expr = ex; #ifdef DEBUG print_expr("init-expr after cast", expr); #endif DEBUG if (expr->ex_class == Float) C_con_fcon(expr->FL_VALUE, expr->ex_type->tp_size); else if (expr->ex_class == Oper && expr->OP_OPER == INT2FLOAT) { /* float f = 1; */ expr = expr->OP_RIGHT; if (is_cp_cst(expr)) C_con_fcon(long2str((long)expr->VL_VALUE, 10), tp->tp_size); else illegal_init_cst(expr); } else illegal_init_cst(expr); break; #endif NOFLOAT #ifndef NOBITFIELD case FIELD: ch7cast(&ex, '=', tp->tp_up); expr = ex; #ifdef DEBUG print_expr("init-expr after cast", expr); #endif DEBUG if (is_cp_cst(expr)) put_bf(tp, expr->VL_VALUE); else illegal_init_cst(expr); break; #endif NOBITFIELD case ERRONEOUS: break; default: crash("check_ival"); } } /* ch_array() initialises an array of characters when given a string constant. Alignment is taken care of. */ ch_array(tpp, ex) struct type **tpp; /* type tp = array of characters */ struct expr *ex; { register struct type *tp = *tpp; register arith length = ex->SG_LEN; char *s; arith ntopad; ASSERT(ex->ex_class == String); if (tp->tp_size == (arith)-1) { /* set the dimension */ tp = *tpp = construct_type(ARRAY, tp->tp_up, length); ntopad = align(tp->tp_size, word_size) - tp->tp_size; } else { arith dim = tp->tp_size / tp->tp_up->tp_size; extern char options[]; if (length > dim) { if (options['R']) too_many_initialisers(ex); else { /* don't take the null byte into account */ if (length > dim + 1) expr_warning(ex, "too many initialisers"); length = dim; } } ntopad = align(dim, word_size) - length; } /* throw out the characters of the already prepared string */ s = Malloc((unsigned) (length + ntopad)); clear(s, (int) (length + ntopad)); strncpy(s, ex->SG_VALUE, (int) length); free(ex->SG_VALUE); str_cst(s, (int) (length + ntopad)); free(s); } /* As long as some parts of the pipeline cannot handle very long string constants, string constants are written out in chunks */ str_cst(str, len) register char *str; register int len; { arith chunksize = ((127 + word_size) / word_size) * word_size; while (len > chunksize) { C_con_scon(str, chunksize); len -= chunksize; str += chunksize; } C_con_scon(str, (arith) len); } #ifndef NOBITFIELD /* put_bf() takes care of the initialisation of (bit-)field selectors of a struct: each time such an initialisation takes place, put_bf() is called instead of the normal code generating routines. Put_bf() stores the given integral value into "field" and "throws" the result of "field" out if the current selector is the last of this number of fields stored at the same address. */ put_bf(tp, val) struct type *tp; arith val; { static long field = (arith)0; static arith offset = (arith)-1; register struct field *fd = tp->tp_field; register struct sdef *sd = fd->fd_sdef; static struct expr exp; ASSERT(sd); if (offset == (arith)-1) { /* first bitfield in this field */ offset = sd->sd_offset; exp.ex_type = tp->tp_up; exp.ex_class = Value; exp.VL_CLASS = Const; } if (val != 0) /* insert the value into "field" */ field |= (val & fd->fd_mask) << fd->fd_shift; if (sd->sd_sdef == 0 || sd->sd_sdef->sd_offset != offset) { /* the selector was the last stored at this address */ exp.VL_VALUE = field; con_int(&exp); field = (arith)0; offset = (arith)-1; } } #endif NOBITFIELD int zero_bytes(sd) register struct sdef *sd; { /* fills the space between a selector of a struct and the next selector of that struct with zero-bytes. */ register int n = sd->sd_sdef->sd_offset - sd->sd_offset - size_of_type(sd->sd_type, "struct member"); register int count = n; while (n-- > 0) con_nullbyte(); return count; } int valid_type(tp, str) struct type *tp; char *str; { if (tp->tp_size < 0) { error("size of %s unknown", str); return 0; } return 1; } con_int(ex) register struct expr *ex; { register struct type *tp = ex->ex_type; ASSERT(is_cp_cst(ex)); if (tp->tp_unsigned) C_con_ucon(long2str((long)ex->VL_VALUE, -10), tp->tp_size); else C_con_icon(long2str((long)ex->VL_VALUE, 10), tp->tp_size); } illegal_init_cst(ex) struct expr *ex; { expr_error(ex, "illegal initialisation constant"); } too_many_initialisers(ex) struct expr *ex; { expr_error(ex, "too many initialisers"); } aggregate_type(tp) register struct type *tp; { return tp->tp_fund == ARRAY || tp->tp_fund == STRUCT; }