// SPDX-License-Identifier: GPL-2.0/* * Copyright (C) 2002 Roman Zippel <zippel@linux-m68k.org> */ #include <ctype.h>#include <errno.h>#include <stdio.h>#include <stdlib.h>#include <string.h> #include "lkc.h" #define DEBUG_EXPR 0 static struct expr *expr_eliminate_yn(struct expr *e); struct expr *expr_alloc_symbol(struct symbol *sym){ struct expr *e = xcalloc(1, sizeof(*e)); e->type = E_SYMBOL; e->left.sym = sym; return e;} struct expr *expr_alloc_one(enum expr_type type, struct expr *ce){ struct expr *e = xcalloc(1, sizeof(*e)); e->type = type; e->left.expr = ce; return e;} struct expr *expr_alloc_two(enum expr_type type, struct expr *e1, struct expr *e2){ struct expr *e = xcalloc(1, sizeof(*e)); e->type = type; e->left.expr = e1; e->right.expr = e2; return e;} struct expr *expr_alloc_comp(enum expr_type type, struct symbol *s1, struct symbol *s2){ struct expr *e = xcalloc(1, sizeof(*e)); e->type = type; e->left.sym = s1; e->right.sym = s2; return e;} struct expr *expr_alloc_and(struct expr *e1, struct expr *e2){ if (!e1) return e2; return e2 ? expr_alloc_two(E_AND, e1, e2) : e1;} struct expr *expr_alloc_or(struct expr *e1, struct expr *e2){ if (!e1) return e2; return e2 ? expr_alloc_two(E_OR, e1, e2) : e1;} struct expr *expr_copy(const struct expr *org){ struct expr *e; if (!org) return NULL; e = xmalloc(sizeof(*org)); memcpy(e, org, sizeof(*org)); switch (org->type) { case E_SYMBOL: e->left = org->left; break; case E_NOT: e->left.expr = expr_copy(org->left.expr); break; case E_EQUAL: case E_GEQ: case E_GTH: case E_LEQ: case E_LTH: case E_UNEQUAL: e->left.sym = org->left.sym; e->right.sym = org->right.sym; break; case E_AND: case E_OR: case E_LIST: e->left.expr = expr_copy(org->left.expr); e->right.expr = expr_copy(org->right.expr); break; default: fprintf(stderr, "can't copy type %d\n", e->type); free(e); e = NULL; break; } return e;} void expr_free(struct expr *e){ if (!e) return; switch (e->type) { case E_SYMBOL: break; case E_NOT: expr_free(e->left.expr); break; case E_EQUAL: case E_GEQ: case E_GTH: case E_LEQ: case E_LTH: case E_UNEQUAL: break; case E_OR: case E_AND: expr_free(e->left.expr); expr_free(e->right.expr); break; default: fprintf(stderr, "how to free type %d?\n", e->type); break; } free(e);} static int trans_count; #define e1 (*ep1)#define e2 (*ep2) /* * expr_eliminate_eq() helper. * * Walks the two expression trees given in 'ep1' and 'ep2'. Any node that does * not have type 'type' (E_OR/E_AND) is considered a leaf, and is compared * against all other leaves. Two equal leaves are both replaced with either 'y' * or 'n' as appropriate for 'type', to be eliminated later. */static void __expr_eliminate_eq(enum expr_type type, struct expr **ep1, struct expr **ep2){ /* Recurse down to leaves */ if (e1->type == type) { __expr_eliminate_eq(type, &e1->left.expr, &e2); __expr_eliminate_eq(type, &e1->right.expr, &e2); return; } if (e2->type == type) { __expr_eliminate_eq(type, &e1, &e2->left.expr); __expr_eliminate_eq(type, &e1, &e2->right.expr); return; } /* e1 and e2 are leaves. Compare them. */ if (e1->type == E_SYMBOL && e2->type == E_SYMBOL && e1->left.sym == e2->left.sym && (e1->left.sym == &symbol_yes || e1->left.sym == &symbol_no)) return; if (!expr_eq(e1, e2)) return; /* e1 and e2 are equal leaves. Prepare them for elimination. */ trans_count++; expr_free(e1); expr_free(e2); switch (type) { case E_OR: e1 = expr_alloc_symbol(&symbol_no); e2 = expr_alloc_symbol(&symbol_no); break; case E_AND: e1 = expr_alloc_symbol(&symbol_yes); e2 = expr_alloc_symbol(&symbol_yes); break; default: ; }} /* * Rewrites the expressions 'ep1' and 'ep2' to remove operands common to both. * Example reductions: * * ep1: A && B -> ep1: y * ep2: A && B && C -> ep2: C * * ep1: A || B -> ep1: n * ep2: A || B || C -> ep2: C * * ep1: A && (B && FOO) -> ep1: FOO * ep2: (BAR && B) && A -> ep2: BAR * * ep1: A && (B || C) -> ep1: y * ep2: (C || B) && A -> ep2: y * * Comparisons are done between all operands at the same "level" of && or ||. * For example, in the expression 'e1 && (e2 || e3) && (e4 || e5)', the * following operands will be compared: * * - 'e1', 'e2 || e3', and 'e4 || e5', against each other * - e2 against e3 * - e4 against e5 * * Parentheses are irrelevant within a single level. 'e1 && (e2 && e3)' and * '(e1 && e2) && e3' are both a single level. * * See __expr_eliminate_eq() as well. */void expr_eliminate_eq(struct expr **ep1, struct expr **ep2){ if (!e1 || !e2) return; switch (e1->type) { case E_OR: case E_AND: __expr_eliminate_eq(e1->type, ep1, ep2); default: ; } if (e1->type != e2->type) switch (e2->type) { case E_OR: case E_AND: __expr_eliminate_eq(e2->type, ep1, ep2); default: ; } e1 = expr_eliminate_yn(e1); e2 = expr_eliminate_yn(e2);} #undef e1#undef e2 /* * Returns true if 'e1' and 'e2' are equal, after minor simplification. Two * &&/|| expressions are considered equal if every operand in one expression * equals some operand in the other (operands do not need to appear in the same * order), recursively. */int expr_eq(struct expr *e1, struct expr *e2){ int res, old_count; /* * A NULL expr is taken to be yes, but there's also a different way to * represent yes. expr_is_yes() checks for either representation. */ if (!e1 || !e2) return expr_is_yes(e1) && expr_is_yes(e2); if (e1->type != e2->type) return 0; switch (e1->type) { case E_EQUAL: case E_GEQ: case E_GTH: case E_LEQ: case E_LTH: case E_UNEQUAL: return e1->left.sym == e2->left.sym && e1->right.sym == e2->right.sym; case E_SYMBOL: return e1->left.sym == e2->left.sym; case E_NOT: return expr_eq(e1->left.expr, e2->left.expr); case E_AND: case E_OR: e1 = expr_copy(e1); e2 = expr_copy(e2); old_count = trans_count; expr_eliminate_eq(&e1, &e2); res = (e1->type == E_SYMBOL && e2->type == E_SYMBOL && e1->left.sym == e2->left.sym); expr_free(e1); expr_free(e2); trans_count = old_count; return res; case E_LIST: case E_RANGE: case E_NONE: /* panic */; } if (DEBUG_EXPR) { expr_fprint(e1, stdout); printf(" = "); expr_fprint(e2, stdout); printf(" ?\n"); } return 0;} /* * Recursively performs the following simplifications in-place (as well as the * corresponding simplifications with swapped operands): * * expr && n -> n * expr && y -> expr * expr || n -> expr * expr || y -> y * * Returns the optimized expression. */static struct expr *expr_eliminate_yn(struct expr *e){ struct expr *tmp; if (e) switch (e->type) { case E_AND: e->left.expr = expr_eliminate_yn(e->left.expr); e->right.expr = expr_eliminate_yn(e->right.expr); if (e->left.expr->type == E_SYMBOL) { if (e->left.expr->left.sym == &symbol_no) { expr_free(e->left.expr); expr_free(e->right.expr); e->type = E_SYMBOL; e->left.sym = &symbol_no; e->right.expr = NULL; return e; } else if (e->left.expr->left.sym == &symbol_yes) { free(e->left.expr); tmp = e->right.expr; *e = *(e->right.expr); free(tmp); return e; } } if (e->right.expr->type == E_SYMBOL) { if (e->right.expr->left.sym == &symbol_no) { expr_free(e->left.expr); expr_free(e->right.expr); e->type = E_SYMBOL; e->left.sym = &symbol_no; e->right.expr = NULL; return e; } else if (e->right.expr->left.sym == &symbol_yes) { free(e->right.expr); tmp = e->left.expr; *e = *(e->left.expr); free(tmp); return e; } } break; case E_OR: e->left.expr = expr_eliminate_yn(e->left.expr); e->right.expr = expr_eliminate_yn(e->right.expr); if (e->left.expr->type == E_SYMBOL) { if (e->left.expr->left.sym == &symbol_no) { free(e->left.expr); tmp = e->right.expr; *e = *(e->right.expr); free(tmp); return e; } else if (e->left.expr->left.sym == &symbol_yes) { expr_free(e->left.expr); expr_free(e->right.expr); e->type = E_SYMBOL; e->left.sym = &symbol_yes; e->right.expr = NULL; return e; } } if (e->right.expr->type == E_SYMBOL) { if (e->right.expr->left.sym == &symbol_no) { free(e->right.expr); tmp = e->left.expr; *e = *(e->left.expr); free(tmp); return e; } else if (e->right.expr->left.sym == &symbol_yes) { expr_free(e->left.expr); expr_free(e->right.expr); e->type = E_SYMBOL; e->left.sym = &symbol_yes; e->right.expr = NULL; return e; } } break; default: ; } return e;} /* * bool FOO!=n => FOO */struct expr *expr_trans_bool(struct expr *e){ if (!e) return NULL; switch (e->type) { case E_AND: case E_OR: case E_NOT: e->left.expr = expr_trans_bool(e->left.expr); e->right.expr = expr_trans_bool(e->right.expr); break; case E_UNEQUAL: // FOO!=n -> FOO if (e->left.sym->type == S_TRISTATE) { if (e->right.sym == &symbol_no) { e->type = E_SYMBOL; e->right.sym = NULL; } } break; default: ; } return e;} /* * e1 || e2 -> ? */static struct expr *expr_join_or(struct expr *e1, struct expr *e2){ struct expr *tmp; struct symbol *sym1, *sym2; if (expr_eq(e1, e2)) return expr_copy(e1); if (e1->type != E_EQUAL && e1->type != E_UNEQUAL && e1->type != E_SYMBOL && e1->type != E_NOT) return NULL; if (e2->type != E_EQUAL && e2->type != E_UNEQUAL && e2->type != E_SYMBOL && e2->type != E_NOT) return NULL; if (e1->type == E_NOT) { tmp = e1->left.expr; if (tmp->type != E_EQUAL && tmp->type != E_UNEQUAL && tmp->type != E_SYMBOL) return NULL; sym1 = tmp->left.sym; } else sym1 = e1->left.sym; if (e2->type == E_NOT) { if (e2->left.expr->type != E_SYMBOL) return NULL; sym2 = e2->left.expr->left.sym; } else sym2 = e2->left.sym; if (sym1 != sym2) return NULL; if (sym1->type != S_BOOLEAN && sym1->type != S_TRISTATE) return NULL; if (sym1->type == S_TRISTATE) { if (e1->type == E_EQUAL && e2->type == E_EQUAL && ((e1->right.sym == &symbol_yes && e2->right.sym == &symbol_mod) || (e1->right.sym == &symbol_mod && e2->right.sym == &symbol_yes))) { // (a='y') || (a='m') -> (a!='n') return expr_alloc_comp(E_UNEQUAL, sym1, &symbol_no); } if (e1->type == E_EQUAL && e2->type == E_EQUAL && ((e1->right.sym == &symbol_yes && e2->right.sym == &symbol_no) || (e1->right.sym == &symbol_no && e2->right.sym == &symbol_yes))) { // (a='y') || (a='n') -> (a!='m') return expr_alloc_comp(E_UNEQUAL, sym1, &symbol_mod); } if (e1->type == E_EQUAL && e2->type == E_EQUAL && ((e1->right.sym == &symbol_mod && e2->right.sym == &symbol_no) || (e1->right.sym == &symbol_no && e2->right.sym == &symbol_mod))) { // (a='m') || (a='n') -> (a!='y') return expr_alloc_comp(E_UNEQUAL, sym1, &symbol_yes); } } if (sym1->type == S_BOOLEAN && sym1 == sym2) { if ((e1->type == E_NOT && e1->left.expr->type == E_SYMBOL && e2->type == E_SYMBOL) || (e2->type == E_NOT && e2->left.expr->type == E_SYMBOL && e1->type == E_SYMBOL)) return expr_alloc_symbol(&symbol_yes); } if (DEBUG_EXPR) { printf("optimize ("); expr_fprint(e1, stdout); printf(") || ("); expr_fprint(e2, stdout); printf(")?\n"); } return NULL;} static struct expr *expr_join_and(struct expr *e1, struct expr *e2){ struct expr *tmp; struct symbol *sym1, *sym2; if (expr_eq(e1, e2))Lines 1–500 of 1302. 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// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2002 Roman Zippel <zippel@linux-m68k.org> */ #include <ctype.h> #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include "lkc.h" #define DEBUG_EXPR 0 static struct expr *expr_eliminate_yn(struct expr *e); struct expr *expr_alloc_symbol(struct symbol *sym) { struct expr *e = xcalloc(1, sizeof(*e)); e->type = E_SYMBOL; e->left.sym = sym; return e; } struct expr *expr_alloc_one(enum expr_type type, struct expr *ce) { struct expr *e = xcalloc(1, sizeof(*e)); e->type = type; e->left.expr = ce; return e; } struct expr *expr_alloc_two(enum expr_type type, struct expr *e1, struct expr *e2) { struct expr *e = xcalloc(1, sizeof(*e)); e->type = type; e->left.expr = e1; e->right.expr = e2; return e; } struct expr *expr_alloc_comp(enum expr_type type, struct symbol *s1, struct symbol *s2) { struct expr *e = xcalloc(1, sizeof(*e)); e->type = type; e->left.sym = s1; e->right.sym = s2; return e; } struct expr *expr_alloc_and(struct expr *e1, struct expr *e2) { if (!e1) return e2; return e2 ? expr_alloc_two(E_AND, e1, e2) : e1; } struct expr *expr_alloc_or(struct expr *e1, struct expr *e2) { if (!e1) return e2; return e2 ? expr_alloc_two(E_OR, e1, e2) : e1; } struct expr *expr_copy(const struct expr *org) { struct expr *e; if (!org) return NULL; e = xmalloc(sizeof(*org)); memcpy(e, org, sizeof(*org)); switch (org->type) { case E_SYMBOL: e->left = org->left; break; case E_NOT: e->left.expr = expr_copy(org->left.expr); break; case E_EQUAL: case E_GEQ: case E_GTH: case E_LEQ: case E_LTH: case E_UNEQUAL: e->left.sym = org->left.sym; e->right.sym = org->right.sym; break; case E_AND: case E_OR: case E_LIST: e->left.expr = expr_copy(org->left.expr); e->right.expr = expr_copy(org->right.expr); break; default: fprintf(stderr, "can't copy type %d\n", e->type); free(e); e = NULL; break; } return e; } void expr_free(struct expr *e) { if (!e) return; switch (e->type) { case E_SYMBOL: break; case E_NOT: expr_free(e->left.expr); break; case E_EQUAL: case E_GEQ: case E_GTH: case E_LEQ: case E_LTH: case E_UNEQUAL: break; case E_OR: case E_AND: expr_free(e->left.expr); expr_free(e->right.expr); break; default: fprintf(stderr, "how to free type %d?\n", e->type); break; } free(e); } static int trans_count; #define e1 (*ep1) #define e2 (*ep2) /* * expr_eliminate_eq() helper. * * Walks the two expression trees given in 'ep1' and 'ep2'. Any node that does * not have type 'type' (E_OR/E_AND) is considered a leaf, and is compared * against all other leaves. Two equal leaves are both replaced with either 'y' * or 'n' as appropriate for 'type', to be eliminated later. */ static void __expr_eliminate_eq(enum expr_type type, struct expr **ep1, struct expr **ep2) { /* Recurse down to leaves */ if (e1->type == type) { __expr_eliminate_eq(type, &e1->left.expr, &e2); __expr_eliminate_eq(type, &e1->right.expr, &e2); return; } if (e2->type == type) { __expr_eliminate_eq(type, &e1, &e2->left.expr); __expr_eliminate_eq(type, &e1, &e2->right.expr); return; } /* e1 and e2 are leaves. Compare them. */ if (e1->type == E_SYMBOL && e2->type == E_SYMBOL && e1->left.sym == e2->left.sym && (e1->left.sym == &symbol_yes || e1->left.sym == &symbol_no)) return; if (!expr_eq(e1, e2)) return; /* e1 and e2 are equal leaves. Prepare them for elimination. */ trans_count++; expr_free(e1); expr_free(e2); switch (type) { case E_OR: e1 = expr_alloc_symbol(&symbol_no); e2 = expr_alloc_symbol(&symbol_no); break; case E_AND: e1 = expr_alloc_symbol(&symbol_yes); e2 = expr_alloc_symbol(&symbol_yes); break; default: ; } } /* * Rewrites the expressions 'ep1' and 'ep2' to remove operands common to both. * Example reductions: * * ep1: A && B -> ep1: y * ep2: A && B && C -> ep2: C * * ep1: A || B -> ep1: n * ep2: A || B || C -> ep2: C * * ep1: A && (B && FOO) -> ep1: FOO * ep2: (BAR && B) && A -> ep2: BAR * * ep1: A && (B || C) -> ep1: y * ep2: (C || B) && A -> ep2: y * * Comparisons are done between all operands at the same "level" of && or ||. * For example, in the expression 'e1 && (e2 || e3) && (e4 || e5)', the * following operands will be compared: * * - 'e1', 'e2 || e3', and 'e4 || e5', against each other * - e2 against e3 * - e4 against e5 * * Parentheses are irrelevant within a single level. 'e1 && (e2 && e3)' and * '(e1 && e2) && e3' are both a single level. * * See __expr_eliminate_eq() as well. */ void expr_eliminate_eq(struct expr **ep1, struct expr **ep2) { if (!e1 || !e2) return; switch (e1->type) { case E_OR: case E_AND: __expr_eliminate_eq(e1->type, ep1, ep2); default: ; } if (e1->type != e2->type) switch (e2->type) { case E_OR: case E_AND: __expr_eliminate_eq(e2->type, ep1, ep2); default: ; } e1 = expr_eliminate_yn(e1); e2 = expr_eliminate_yn(e2); } #undef e1 #undef e2 /* * Returns true if 'e1' and 'e2' are equal, after minor simplification. Two * &&/|| expressions are considered equal if every operand in one expression * equals some operand in the other (operands do not need to appear in the same * order), recursively. */ int expr_eq(struct expr *e1, struct expr *e2) { int res, old_count; /* * A NULL expr is taken to be yes, but there's also a different way to * represent yes. expr_is_yes() checks for either representation. */ if (!e1 || !e2) return expr_is_yes(e1) && expr_is_yes(e2); if (e1->type != e2->type) return 0; switch (e1->type) { case E_EQUAL: case E_GEQ: case E_GTH: case E_LEQ: case E_LTH: case E_UNEQUAL: return e1->left.sym == e2->left.sym && e1->right.sym == e2->right.sym; case E_SYMBOL: return e1->left.sym == e2->left.sym; case E_NOT: return expr_eq(e1->left.expr, e2->left.expr); case E_AND: case E_OR: e1 = expr_copy(e1); e2 = expr_copy(e2); old_count = trans_count; expr_eliminate_eq(&e1, &e2); res = (e1->type == E_SYMBOL && e2->type == E_SYMBOL && e1->left.sym == e2->left.sym); expr_free(e1); expr_free(e2); trans_count = old_count; return res; case E_LIST: case E_RANGE: case E_NONE: /* panic */; } if (DEBUG_EXPR) { expr_fprint(e1, stdout); printf(" = "); expr_fprint(e2, stdout); printf(" ?\n"); } return 0; } /* * Recursively performs the following simplifications in-place (as well as the * corresponding simplifications with swapped operands): * * expr && n -> n * expr && y -> expr * expr || n -> expr * expr || y -> y * * Returns the optimized expression. */ static struct expr *expr_eliminate_yn(struct expr *e) { struct expr *tmp; if (e) switch (e->type) { case E_AND: e->left.expr = expr_eliminate_yn(e->left.expr); e->right.expr = expr_eliminate_yn(e->right.expr); if (e->left.expr->type == E_SYMBOL) { if (e->left.expr->left.sym == &symbol_no) { expr_free(e->left.expr); expr_free(e->right.expr); e->type = E_SYMBOL; e->left.sym = &symbol_no; e->right.expr = NULL; return e; } else if (e->left.expr->left.sym == &symbol_yes) { free(e->left.expr); tmp = e->right.expr; *e = *(e->right.expr); free(tmp); return e; } } if (e->right.expr->type == E_SYMBOL) { if (e->right.expr->left.sym == &symbol_no) { expr_free(e->left.expr); expr_free(e->right.expr); e->type = E_SYMBOL; e->left.sym = &symbol_no; e->right.expr = NULL; return e; } else if (e->right.expr->left.sym == &symbol_yes) { free(e->right.expr); tmp = e->left.expr; *e = *(e->left.expr); free(tmp); return e; } } break; case E_OR: e->left.expr = expr_eliminate_yn(e->left.expr); e->right.expr = expr_eliminate_yn(e->right.expr); if (e->left.expr->type == E_SYMBOL) { if (e->left.expr->left.sym == &symbol_no) { free(e->left.expr); tmp = e->right.expr; *e = *(e->right.expr); free(tmp); return e; } else if (e->left.expr->left.sym == &symbol_yes) { expr_free(e->left.expr); expr_free(e->right.expr); e->type = E_SYMBOL; e->left.sym = &symbol_yes; e->right.expr = NULL; return e; } } if (e->right.expr->type == E_SYMBOL) { if (e->right.expr->left.sym == &symbol_no) { free(e->right.expr); tmp = e->left.expr; *e = *(e->left.expr); free(tmp); return e; } else if (e->right.expr->left.sym == &symbol_yes) { expr_free(e->left.expr); expr_free(e->right.expr); e->type = E_SYMBOL; e->left.sym = &symbol_yes; e->right.expr = NULL; return e; } } break; default: ; } return e; } /* * bool FOO!=n => FOO */ struct expr *expr_trans_bool(struct expr *e) { if (!e) return NULL; switch (e->type) { case E_AND: case E_OR: case E_NOT: e->left.expr = expr_trans_bool(e->left.expr); e->right.expr = expr_trans_bool(e->right.expr); break; case E_UNEQUAL: // FOO!=n -> FOO if (e->left.sym->type == S_TRISTATE) { if (e->right.sym == &symbol_no) { e->type = E_SYMBOL; e->right.sym = NULL; } } break; default: ; } return e; } /* * e1 || e2 -> ? */ static struct expr *expr_join_or(struct expr *e1, struct expr *e2) { struct expr *tmp; struct symbol *sym1, *sym2; if (expr_eq(e1, e2)) return expr_copy(e1); if (e1->type != E_EQUAL && e1->type != E_UNEQUAL && e1->type != E_SYMBOL && e1->type != E_NOT) return NULL; if (e2->type != E_EQUAL && e2->type != E_UNEQUAL && e2->type != E_SYMBOL && e2->type != E_NOT) return NULL; if (e1->type == E_NOT) { tmp = e1->left.expr; if (tmp->type != E_EQUAL && tmp->type != E_UNEQUAL && tmp->type != E_SYMBOL) return NULL; sym1 = tmp->left.sym; } else sym1 = e1->left.sym; if (e2->type == E_NOT) { if (e2->left.expr->type != E_SYMBOL) return NULL; sym2 = e2->left.expr->left.sym; } else sym2 = e2->left.sym; if (sym1 != sym2) return NULL; if (sym1->type != S_BOOLEAN && sym1->type != S_TRISTATE) return NULL; if (sym1->type == S_TRISTATE) { if (e1->type == E_EQUAL && e2->type == E_EQUAL && ((e1->right.sym == &symbol_yes && e2->right.sym == &symbol_mod) || (e1->right.sym == &symbol_mod && e2->right.sym == &symbol_yes))) { // (a='y') || (a='m') -> (a!='n') return expr_alloc_comp(E_UNEQUAL, sym1, &symbol_no); } if (e1->type == E_EQUAL && e2->type == E_EQUAL && ((e1->right.sym == &symbol_yes && e2->right.sym == &symbol_no) || (e1->right.sym == &symbol_no && e2->right.sym == &symbol_yes))) { // (a='y') || (a='n') -> (a!='m') return expr_alloc_comp(E_UNEQUAL, sym1, &symbol_mod); } if (e1->type == E_EQUAL && e2->type == E_EQUAL && ((e1->right.sym == &symbol_mod && e2->right.sym == &symbol_no) || (e1->right.sym == &symbol_no && e2->right.sym == &symbol_mod))) { // (a='m') || (a='n') -> (a!='y') return expr_alloc_comp(E_UNEQUAL, sym1, &symbol_yes); } } if (sym1->type == S_BOOLEAN && sym1 == sym2) { if ((e1->type == E_NOT && e1->left.expr->type == E_SYMBOL && e2->type == E_SYMBOL) || (e2->type == E_NOT && e2->left.expr->type == E_SYMBOL && e1->type == E_SYMBOL)) return expr_alloc_symbol(&symbol_yes); } if (DEBUG_EXPR) { printf("optimize ("); expr_fprint(e1, stdout); printf(") || ("); expr_fprint(e2, stdout); printf(")?\n"); } return NULL; } static struct expr *expr_join_and(struct expr *e1, struct expr *e2) { struct expr *tmp; struct symbol *sym1, *sym2; if (expr_eq(e1, e2))