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-rw-r--r--peephole.c559
1 files changed, 559 insertions, 0 deletions
diff --git a/peephole.c b/peephole.c
new file mode 100644
index 0000000..42e77ee
--- /dev/null
+++ b/peephole.c
@@ -0,0 +1,559 @@
+#include <stdarg.h>
+#include <assert.h>
+
+#include "peephole.h"
+#include "strio.h"
+
+extern int no_opt;
+
+static inline int node_op_communative(NodeType t) {
+ return NMASK(t) & (NM_OP_ADD | NM_OP_MUL | NM_OP_AND | NM_OP_XOR | NM_OP_OR | NM_CMP_EQL | NM_CMP_NEQ);
+ /*NodeType ops[] = { N_OP_ADD, N_OP_MUL, N_OP_AND, N_OP_XOR, N_OP_OR, N_CMP_EQL, N_CMP_NEQ };
+ for (unsigned i = 0; i < sizeof ops / sizeof *ops; i++) {
+ if (ops[i] == t) return 1;
+ }
+ return 0;*/
+}
+
+static inline int node_op_associative(NodeType t) {
+ /*NodeType ops[] = { N_OP_ADD, N_OP_MUL, N_OP_AND, N_OP_XOR, N_OP_OR };
+ for (unsigned i = 0; i < sizeof ops / sizeof *ops; i++) {
+ if (ops[i] == t) return 1;
+ }
+ return 0;*/
+ return NMASK(t) & (NM_OP_ADD | NM_OP_MUL | NM_OP_AND | NM_OP_XOR | NM_OP_OR);
+}
+
+static inline int node_op_comparison(NodeType t) {
+ /*NodeType ops[] = { N_CMP_EQL, N_CMP_NEQ, N_CMP_LES, N_CMP_GTR, N_CMP_LTE, N_CMP_GTE };
+ for (unsigned i = 0; i < sizeof ops / sizeof *ops; i++) {
+ if (ops[i] == t) return 1;
+ }
+ return 0;*/
+ return NMASK(t) & (NM_CMP_EQL | NM_CMP_NEQ | NM_CMP_LES | NM_CMP_GTR | NM_CMP_LTE | NM_CMP_GTE);
+}
+
+/* when applied to the same input, at least one must be true */
+static inline NodeType node_cmp_opposite(NodeType a) {
+ switch (a) {
+ case N_CMP_EQL: return N_CMP_NEQ;
+ case N_CMP_NEQ: return N_CMP_EQL;
+ case N_CMP_LES: return N_CMP_GTE;
+ case N_CMP_GTE: return N_CMP_LES;
+ case N_CMP_GTR: return N_CMP_LTE;
+ case N_CMP_LTE: return N_CMP_GTR;
+ default: return N_NONE;
+ }
+}
+
+static inline NodeType node_cmp_flip_sign(NodeType a) {
+ switch (a) {
+ case N_CMP_LES: return N_CMP_GTR;
+ case N_CMP_LTE: return N_CMP_GTE;
+ case N_CMP_GTR: return N_CMP_LES;
+ case N_CMP_GTE: return N_CMP_LTE;
+ default: return a;
+ }
+}
+
+/* when applied to the same input, at least one must be false */
+static inline int node_cmp_incompat(NodeType a, NodeType b) {
+ struct { NodeType l, r; } pairs[] = {
+ { N_CMP_EQL, N_CMP_NEQ },
+ { N_CMP_LES, N_CMP_GTE },
+ { N_CMP_GTR, N_CMP_LTE },
+ { N_CMP_LES, N_CMP_GTR },
+ };
+ for (unsigned i = 0; i < sizeof pairs / sizeof *pairs; i++) {
+ if ((pairs[i].l == a && pairs[i].r == b) || (pairs[i].l == b && pairs[i].r == a)) {
+ return 1;
+ }
+ }
+ return 0;
+}
+
+Value node_compute(Node *n, Lexer *l) {
+ Type lit_type = { .lvl = T_BOT };
+ for (int i = 1; i < n->in.len; i++) {
+ Node *p = IN(n, i);
+ if (p->type.lvl != T_CONST) {
+ lit_type.lvl = T_BOT;
+ break;
+ }
+ if (!type_eql(&p->type, &lit_type)) {
+ if (lit_type.lvl == T_BOT) {
+ lit_type = p->type;
+ } else {
+ lit_type.lvl = T_BOT;
+ break;
+ }
+ }
+ }
+
+ if (lit_type.lvl != T_CONST) return n->val;
+
+ Value v = { .type = lit_type };
+
+ if (lit_type.t == T_INT) {
+ switch (n->op) {
+ case N_OP_NEG: v.i = -CAR(n)->val.i; break;
+ case N_OP_NOT: v.i = ~CAR(n)->val.i; break;
+ case N_OP_ADD: v.i = CAR(n)->val.i + CDR(n)->val.i; break;
+ case N_OP_SUB: v.i = CAR(n)->val.i - CDR(n)->val.i; break;
+ case N_OP_MUL: v.i = CAR(n)->val.i * CDR(n)->val.i; break;
+ case N_OP_DIV:
+ if (CDR(n)->val.i == 0) {
+ lex_error_at(l, CDR(n)->src_pos, LE_ERROR, S("divisor always evaluates to zero"));
+ }
+ v.i = CAR(n)->val.i / CDR(n)->val.i;
+ break;
+ case N_OP_AND: v.i = CAR(n)->val.i & CDR(n)->val.i; break;
+ case N_OP_OR: v.i = CAR(n)->val.i | CDR(n)->val.i; break;
+ case N_OP_XOR: v.i = CAR(n)->val.i ^ CDR(n)->val.i; break;
+ case N_OP_SHL: v.i = CAR(n)->val.u << CDR(n)->val.u; break;
+ case N_OP_SHR: v.i = CAR(n)->val.u >> CDR(n)->val.u; break;
+ case N_CMP_EQL: v.type.t = T_BOOL; v.i = CAR(n)->val.i == CDR(n)->val.i; break;
+ case N_CMP_NEQ: v.type.t = T_BOOL; v.i = CAR(n)->val.i != CDR(n)->val.i; break;
+ case N_CMP_LES: v.type.t = T_BOOL; v.i = CAR(n)->val.i < CDR(n)->val.i; break;
+ case N_CMP_GTR: v.type.t = T_BOOL; v.i = CAR(n)->val.i > CDR(n)->val.i; break;
+ case N_CMP_LTE: v.type.t = T_BOOL; v.i = CAR(n)->val.i <= CDR(n)->val.i; break;
+ case N_CMP_GTE: v.type.t = T_BOOL; v.i = CAR(n)->val.i >= CDR(n)->val.i; break;
+ default: return n->val;
+ }
+ return v;
+ } else if (lit_type.t == T_BOOL) {
+ switch (n->op) {
+ case N_OP_NOT: v.i = !CAR(n)->val.i; break;
+ case N_CMP_EQL: v.i = CAR(n)->val.i == CDR(n)->val.i; break;
+ case N_CMP_NEQ: v.i = CAR(n)->val.i != CDR(n)->val.i; break;
+ case N_OP_AND: v.i = CAR(n)->val.i && CDR(n)->val.i; break;
+ case N_OP_OR: v.i = CAR(n)->val.i || CDR(n)->val.i; break;
+ case N_OP_XOR: v.i = CAR(n)->val.i ^ CDR(n)->val.i; break;
+ default: return n->val;
+ }
+ return v;
+ }
+
+ return n->val;
+}
+
+#include <stdio.h>
+
+#define NODE(t, ...) node_peephole(node_new(p, t, CTRL(n), __VA_ARGS__), p, l)
+#define OP(...) NODE(n->op, __VA_ARGS__)
+
+static inline int node_eql_i64(Node *n, int64_t i) {
+ return n->op == N_LIT && n->type.t == T_INT && n->val.i == i;
+}
+
+static inline int u64_power_of_2(uint64_t x) {
+ int ldz = 0, tlz = 0;
+ for (int i = 0; i < 64; i++) {
+ if ((x >> i) & 1) break;
+ else tlz++;
+ }
+ for (int i = 0; i < 64; i++) {
+ if ((x << i) & (1UL << 63)) break;
+ else ldz++;
+ }
+ if (ldz + tlz != 63) return 0;
+ return tlz;
+}
+
+/* functions to query the compile-time equivalence of nodes */
+/* fairly conservative of necessity */
+
+static int node_equiv(Node *a, Node *b);
+static int node_known_neg_of(Node *a, Node *b) {
+ if (T(b, N_OP_NEG) && node_equiv(a, CAR(b))) return 1;
+ if (T(a, N_OP_NEG) && node_equiv(CAR(a), b)) return 1;
+ if (T(a, N_LIT) && T(b, N_LIT) && (a->type.t == b->type.t) && b->val.i == -a->val.i) return 1;
+ return 0;
+}
+
+static inline int node_sub_add_equiv(Node *a, Node *b) {
+ if (node_equiv(CAR(a), CAR(b)) && !node_known_neg_of(CDR(a), CDR(b))) return 1;
+ if (node_equiv(CAR(a), CDR(b)) && !node_known_neg_of(CDR(a), CAR(b))) return 1;
+ return 0;
+}
+
+static int node_equiv_input(Node *a, Node *b);
+
+static int node_equiv(Node *a, Node *b) {
+ /* will doing this recursively be too slow? */
+ if (a == b) return 1;
+ if (a->op != b->op) return 0;
+ if (a->in.len != b->in.len) return 0;
+ if (!value_eql(&a->val, &b->val)) return 0;
+ if (!node_equiv_input(a, b)) return 0;
+ return 1;
+}
+
+/* TODO: figure out a more thorough way of comparing node graphs */
+
+static inline int node_known_not_equiv_ord(Node *a, Node *b) {
+ if ((b->op & (NM_OP_ADD | NM_OP_SUB)) && node_equiv(a, CAR(b))
+ && T(CDR(b), N_LIT) && !node_eql_i64(CDR(b), 0)) return 1;
+ if ((a->op & (NM_OP_ADD | NM_OP_SUB)) && node_sub_add_equiv(a, b)) return 1;
+ return 0;
+}
+static inline int node_known_not_equiv(Node *a, Node *b) {
+ return node_known_not_equiv_ord(a, b) || node_known_not_equiv_ord(b, a);
+}
+
+static int node_equiv_input(Node *a, Node *b) {
+ if (a->in.len != b->in.len) return 0;
+ if (CTRL(a) != CTRL(b)) return 0;
+ /* note that this means the order of inputs isn't guaranteed, so be
+ * careful what you use this procedure for */
+ if ((node_op_communative(a->op) || node_op_communative(b->op))
+ && node_equiv(CDR(a), CAR(b))
+ && node_equiv(CAR(a), CDR(b))) {
+ /* assuming input count is 2 */
+ return 1;
+ }
+ for (int i = 1; i < a->in.len; i++) {
+ if (!node_equiv(IN(a, i), IN(b, i))) return 0;
+ }
+ return 1;
+}
+
+Node *node_new_zero(Proc *p, Node *n) {
+ Value v = {
+ .type = {
+ .lvl = T_CONST,
+ .t = n->type.t,
+ },
+ .i = 0
+ };
+ Node *r = node_new_lit(p, v);
+ return r;
+}
+
+static inline int is_zero(Node *n) {
+ return n->type.lvl == T_CONST && (n->type.t == T_INT || n->type.t == T_BOOL) && !n->val.i;
+}
+
+/* needs lexer for error reporting */
+Node *node_idealize(Node *n, Proc *p, Lexer *l) {
+ if (!type_check(n)) {
+ type_err(n, l);
+ }
+
+ if (no_opt) return NULL;
+
+ /* try to compute a literal value */
+
+ if (n->op != N_LIT) {
+ Value v = node_compute(n, l);
+ if (v.type.lvl == T_CONST) {
+ Node *t = node_dedup_lit(p, v);
+ if (t) return t;
+ Node *r = node_new(p, N_LIT, NULL, p->start);
+ r->val = v;
+ r->src_pos = n->src_pos;
+ return r;
+ }
+ }
+
+ /* try to trim duplicate inputs from the graph */
+
+ int same = 1, same_ptr = 1;
+ for (int i = 1; i < n->in.len; i++) {
+ if (IN(n, i) == CAR(n)) continue;
+ same_ptr = 0;
+ if (!node_equiv(IN(n, i), CAR(n))) {
+ same = 0;
+ break;
+ }
+ }
+
+ if (n->in.len > 2 && same && !same_ptr) {
+ Node *r = node_new(p, n->op, NULL);
+ for (int i = 0; i < n->in.len; i++) {
+ node_add(p, CAR(n), r);
+ }
+ return node_peephole(r, p, l);
+ }
+
+ /* transformations to help encourage constant folding */
+ /* the overall trend is to move them rightwards */
+
+ /* need to check for type compatibility */
+ #define C(a, b) type_base_eql(&(a)->type, &(b)->type)
+ if (node_op_communative(n->op)) {
+ /* op(lit, X) -> op(X, lit) */
+ if (T(CAR(n), N_LIT) && !T(CDR(n), N_LIT)) return OP(CDR(n), CAR(n));
+
+ /* op(X, not(Y)) -> op(not(Y), X) */
+ /* shuffle not left to avoid conflict w/ literals */
+ if (T(CDR(n), N_OP_NOT) && !T(CAR(n), N_OP_NOT)) {
+ return NODE(n->op, CDR(n), CAR(n));
+ }
+
+ if (T(CAR(n), N_PHI) && T(CDR(n), N_PHI) && CTRL(CAR(n)) == CTRL(CDR(n))
+ && ((node_equiv(CAAR(n), CDAR(n)) && node_equiv(CADR(n), CDDR(n)))
+ || (node_equiv(CADR(n), CDAR(n)) && node_equiv(CAAR(n), CDDR(n))))) {
+ return OP(CAAR(n), CDAR(n));
+ }
+ }
+
+ if (node_op_associative(n->op)) {
+ /* op(X, op(Y,Z)) -> op(op(Y,Z), X) */
+ if (!T(CAR(n), n->op) && T(CDR(n), n->op)
+ && C(CAR(n), CDAR(n))) return OP(CDR(n), CAR(n));
+
+ /* op(op(X,Y), op(Z, lit)) -> op(op(X, op(Y, Z)), lit) */
+ if (T2(CAR(n), CDR(n), n->op) && T(CDDR(n), N_LIT)
+ && C(CAAR(n), CDAR(n)) && C(CAR(n), CDR(n))) {
+ return OP(OP(CAAR(n), OP(CADR(n), CDAR(n))), CDDR(n));
+ }
+
+ /* op(op(X, lit), lit) -> op(X, op(lit, lit)) */
+ if (T(CDR(n), N_LIT) && T(CAR(n), n->op)
+ && !T(CAAR(n), N_LIT) && T(CADR(n), N_LIT)
+ && C(CADR(n), CDR(n))) {
+ return OP(CAAR(n), OP(CADR(n), CDR(n)));
+ }
+
+ /* op(op(X, lit), Y) -> op(op(X, Y), lit) */
+ if (T(CAR(n), n->op) && !T(CAAR(n), N_LIT)
+ && T(CADR(n), N_LIT) && !T(CDR(n), N_LIT)
+ && C(CADR(n), CDR(n))) {
+ return OP(OP(CAAR(n), CDR(n)), CADR(n));
+ }
+ }
+
+ /* optimize based on situations where the input is partly known (e.g.
+ * one constant input and one not, or identical inputs) */
+
+#define INT_EQ(n, v) ((n)->type.lvl == T_CONST && (n)->type.t == T_INT && (n)->val.i == v)
+#define BOOL_EQ(n, v) ((n)->type.lvl == T_CONST && (n)->type.t == T_BOOL && (n)->val.i == v)
+
+ switch (n->op) {
+ case N_OP_NOT:
+ {
+ NodeType op = node_cmp_opposite(CAR(n)->op);
+ if (op != N_NONE) return NODE(op, CAAR(n), CADR(n));
+ }
+ /* fallthrough */
+ case N_OP_NEG:
+ if (T(CAR(n), n->op)) return CAAR(n);
+ break;
+ case N_OP_ADD:
+ if (same) return NODE(N_OP_MUL, CAR(n), node_new_lit_i64(p, 2));
+ if (CAR(n)->type.t == T_INT) {
+ /* a + ~a = -1 */
+ if (T(CAR(n), N_OP_NOT) && node_equiv(CAAR(n), CDR(n))) return node_new_lit_i64(p, -1);
+ if (T(CDR(n), N_LIT) && CDR(n)->val.i < 0) return NODE(N_OP_SUB, CAR(n), node_new_lit_i64(p, -CDR(n)->val.i));
+ }
+ if (T(CAR(n), N_OP_NEG)) return NODE(N_OP_SUB, CDR(n), CAAR(n));
+ if (T(CDR(n), N_OP_NEG)) return NODE(N_OP_SUB, CAR(n), CDAR(n));
+ if (T(CAR(n), N_OP_SUB) && T(CDR(n), N_OP_SUB)
+ && node_equiv(CAAR(n), CDDR(n)) && node_equiv(CADR(n), CDAR(n))) {
+ return node_new_lit_i64(p, 0);
+ }
+ goto zero_no_effect;
+ case N_OP_SUB:
+ if (same) return node_new_lit_i64(p, 0);
+ if (node_eql_i64(CAR(n), 0)) return NODE(N_OP_NEG, CDR(n));
+ if (node_eql_i64(CDR(n), 0)) return CAR(n);
+ break;
+ case N_OP_MUL:
+ if (node_eql_i64(CDR(n), 0)) return CDR(n);
+ if (node_eql_i64(CDR(n), 1)) return CAR(n);
+ {
+ int po2;
+ if (T(CDR(n), N_LIT) && CDR(n)->type.t == T_INT && (po2 = u64_power_of_2(CDR(n)->val.u))) {;
+ return NODE(N_OP_SHL, CAR(n), node_new_lit_i64(p, po2));
+ }
+ }
+ break;
+ case N_OP_DIV:
+ if (node_eql_i64(CDR(n), 0)) {
+ lex_error_at(l, CDR(n)->src_pos, LE_ERROR, S("divisor always evaluates to zero"));
+ }
+ {
+ int po2;
+ if (T(CDR(n), N_LIT) && CDR(n)->type.t == T_INT && (po2 = u64_power_of_2(CDR(n)->val.u))) {;
+ return NODE(N_OP_SHR, CAR(n), node_new_lit_i64(p, po2));
+ }
+ }
+ break;
+ case N_OP_OR:
+ if (same) return CAR(n);
+ if (is_zero(CDR(n))) return CAR(n);
+ if (BOOL_EQ(CDR(n), 1)) return CDR(n);
+ if (CDR(n)->op == node_cmp_opposite(CAR(n)->op) && node_equiv_input(CAR(n), CDR(n))) {
+ return node_new_lit_bool(p, 1);
+ }
+ if (T(CAR(n), N_CMP_LES) && T(CDR(n), N_CMP_EQL) && node_equiv_input(CAR(n), CDR(n))) {
+ return NODE(N_CMP_LTE, CAAR(n), CADR(n));
+ }
+ if (T(CAR(n), N_CMP_EQL) && T(CDR(n), N_CMP_LES) && node_equiv_input(CAR(n), CDR(n))) {
+ return NODE(N_CMP_LTE, CDAR(n), CDDR(n));
+ }
+ if (T(CAR(n), N_CMP_GTR) && T(CDR(n), N_CMP_EQL) && node_equiv_input(CAR(n), CDR(n))) {
+ return NODE(N_CMP_GTE, CAAR(n), CADR(n));
+ }
+ if (T(CAR(n), N_CMP_EQL) && T(CDR(n), N_CMP_GTR) && node_equiv_input(CAR(n), CDR(n))) {
+ return NODE(N_CMP_GTE, CDAR(n), CDDR(n));
+ }
+ goto zero_no_effect;
+ case N_OP_AND:
+ if (same) return CAR(n);
+ if (BOOL_EQ(CDR(n), 1)) return CAR(n);
+ if (is_zero(CDR(n))) return node_new_zero(p, CDR(n));
+ if (T(CAR(n), N_OP_NOT) && node_equiv(CAAR(n), CDR(n))) return node_new_zero(p, CDR(n));
+ if (node_cmp_incompat(CAR(n)->op, CDR(n)->op) && node_equiv_input(CAR(n), CDR(n))) {
+ return node_new_lit_bool(p, 0);
+ }
+ break;
+ case N_OP_XOR:
+ if (same) return node_new_zero(p, CAR(n));
+ if (CDR(n)->op == node_cmp_opposite(CAR(n)->op) && node_equiv_input(CAR(n), CDR(n))) {
+ return node_new_lit_bool(p, 1);
+ }
+ /* ~bool ^ bool = 1 */
+ /* ~i64 ^ i64 = -1 */
+ if (T(CAR(n), N_OP_NOT) && node_equiv(CAAR(n), CDR(n))) {
+ if (CDR(n)->type.t == T_INT) return node_new_lit_i64(p, -1);
+ if (CDR(n)->type.t == T_BOOL) return node_new_lit_bool(p, 1);
+ }
+zero_no_effect: if (node_eql_i64(CAR(n), 0)) return CDR(n);
+ if (node_eql_i64(CDR(n), 0)) return CAR(n);
+ break;
+ case N_CMP_EQL:
+ if (same) return node_new_lit_bool(p, 1);
+ if (node_known_not_equiv(CAR(n), CDR(n))) return node_new_lit_bool(p, 0);
+ if (BOOL_EQ(CDR(n), 1)) return CAR(n);
+ if (BOOL_EQ(CDR(n), 0)) return NODE(N_OP_NOT, CAR(n));
+ if (T(CAR(n), N_OP_NOT) && node_equiv(CDR(n), CAAR(n))) return node_new_lit_bool(p, 0);
+ break;
+ case N_CMP_NEQ:
+ if (same) return node_new_lit_bool(p, 0);
+ if (node_known_not_equiv(CAR(n), CDR(n))) return node_new_lit_bool(p, 1);
+ if (BOOL_EQ(CDR(n), 0)) return CAR(n);
+ if (BOOL_EQ(CDR(n), 1)) return NODE(N_OP_NOT, CAR(n));
+ break;
+ case N_CMP_LES:
+ if (same) return node_new_lit_bool(p, 0);
+ break;
+ case N_CMP_GTR:
+ if (same) return node_new_lit_bool(p, 0);
+ break;
+ case N_CMP_LTE:
+ if (same) return node_new_lit_bool(p, 1);
+ break;
+ case N_CMP_GTE:
+ if (same) return node_new_lit_bool(p, 1);
+ break;
+
+ case N_IF_ELSE:
+ if (T(CAR(n), N_LIT)) {
+ if (CAR(n)->val.i) {
+ n->val.tuple.data[1].type.lvl = T_XCTRL;
+ } else {
+ n->val.tuple.data[0].type.lvl = T_XCTRL;
+ }
+ }
+ break;
+
+ case N_RETURN:
+ if (CTRL(n)->type.lvl == T_XCTRL) return CTRL(n);
+ break;
+
+ case N_PROJ:
+ if (T(CTRL(n), N_IF_ELSE) && CTRL(n)->type.t == T_TUPLE) {
+ /*if (CTRL(n)->val.tuple.data[n->val.i].type.lvl == T_XCTRL) {
+ return node_new_lit(p, (Value) {
+ .type = { .lvl = T_XCTRL, .t = T_NONE }
+ });
+ }*/
+ if (CTRL(n)->val.tuple.data[(n->val.i + 1) % CTRL(n)->val.tuple.len].type.lvl == T_XCTRL) {
+ return CTRL(CTRL(n));
+ }
+ }
+ break;
+
+ case N_PHI:
+ if (same) return CAR(n);
+ if (CTRL(n)->in.len == 2) {
+ fprintf(stderr, "ctrl: %s\n", node_type_name(CTRL(n)->op));
+ fprintf(stderr, "left: %p\n", (void*)IN(CTRL(n), 0));
+ fprintf(stderr, "right: %p\n", (void*)IN(CTRL(n), 1));
+ if (IN(CTRL(n), 1)->type.lvl == T_XCTRL) return CAR(n);
+ if (IN(CTRL(n), 0)->type.lvl == T_XCTRL) return CDR(n);
+ }
+ break;
+
+ case N_REGION: if (0) {
+ int live_in = 0;
+ for (int i = 0; i < n->in.len; i++) {
+ if (IN(n, i)->type.lvl != T_XCTRL) live_in++;
+ }
+ if (live_in == 1) {
+ for (int i = 0; i < n->in.len; i++) {
+ if (IN(n, i)->type.lvl != T_XCTRL) {
+ return IN(n, i);
+ }
+ }
+ }
+ if (live_in == 0) {
+ return node_new_lit(p, (Value) {
+ .type = { .lvl = T_XCTRL, .t = T_NONE }
+ });
+ }
+ } break;
+
+ default:
+ break;
+ }
+
+ if (node_op_comparison(n->op)) {
+ /* cmp(2a, a + b) -> cmp(a, b) */
+ if (T(CAR(n), N_OP_SHL) && T(CDR(n), N_OP_ADD) && node_eql_i64(CADR(n), 1)) {
+ if (node_equiv(CAAR(n), CDAR(n))) return NODE(n->op, CAAR(n), CDDR(n));
+ if (node_equiv(CAAR(n), CDDR(n))) return NODE(n->op, CAAR(n), CDAR(n));
+ }
+ if (T(CDR(n), N_OP_SHL) && T(CAR(n), N_OP_ADD) && node_eql_i64(CDDR(n), 1)) {
+ if (node_equiv(CDAR(n), CAAR(n))) return NODE(n->op, CDAR(n), CADR(n));
+ if (node_equiv(CDAR(n), CADR(n))) return NODE(n->op, CDAR(n), CAAR(n));
+ }
+ /* cmp(a + b, a + c) -> cmp(b, c) */
+ if (node_op_associative(CAR(n)->op) && T(CAR(n), CDR(n)->op)) {
+ if (node_equiv(CAAR(n), CDAR(n))) return NODE(n->op, CADR(n), CDDR(n));
+ if (node_equiv(CADR(n), CDAR(n))) return NODE(n->op, CAAR(n), CDDR(n));
+ if (node_equiv(CAAR(n), CDDR(n))) return NODE(n->op, CADR(n), CDAR(n));
+ if (node_equiv(CADR(n), CDDR(n))) return NODE(n->op, CAAR(n), CDAR(n));
+ }
+ if (T2(CAR(n), CDR(n), N_OP_SUB)) {
+ /* cmp(a - b, b - a) -> cmp(a, b) */
+ if (node_equiv(CAAR(n), CDDR(n)) && node_equiv(CADR(n), CDAR(n))) {
+ return NODE(n->op, CAAR(n), CDAR(n));
+ }
+ /* cmp(a - b, c - b) -> flipcmp(a, c) */
+ if (node_equiv(CAAR(n), CDAR(n))) {
+ return NODE(node_cmp_flip_sign(n->op), CADR(n), CDDR(n));
+ }
+ }
+ /* cmp(-a, -b) -> flipcmp(a, b) */
+ if (T2(CAR(n), CDR(n), N_OP_NEG)) {
+ return NODE(node_cmp_flip_sign(n->op), CAAR(n), CDAR(n));
+ }
+ }
+
+ return NULL;
+}
+
+Node *node_peephole(Node *n, Proc *p, Lexer *l) {
+ assert(n->refs > 0);
+ Node *r = node_idealize(n, p, l);
+ if (r) {
+ r->src_pos = n->src_pos;
+ NODE_KEEP(p, r, node_kill(n, p));
+ return r;
+ }
+ /* FIXME: figure out why this shows the wrong position when in an assignment */
+ return n;
+}
generated by cgit v1.2.3 (git 2.46.0) at 2025-11-15 10:01:34 +0000