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[qfcc] Propagate double-negative through addition
And convert addition to subtraction when extend expressions are not involved. This has taken my little test down to 56 instructions total (21 for `l p ~l`), down from 74 (39).
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1 changed files with 35 additions and 2 deletions
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@ -74,6 +74,14 @@ ext_expr (expr_t *src, type_t *type, int extend, bool reverse)
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return new_extend_expr (src, type, extend, reverse);
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}
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static bool __attribute__((const))
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anti_com (const expr_t *e)
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{
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return (e->type == ex_expr
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&& (e->e.expr.op == CROSS || e->e.expr.op == WEDGE
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|| e->e.expr.op == '-'));
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}
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static expr_t *
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neg_expr (expr_t *e)
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{
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@ -85,7 +93,11 @@ neg_expr (expr_t *e)
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return e->e.expr.e1;
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}
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auto type = get_type (e);
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e = new_unary_expr ('-', e);
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if (anti_com (e)) {
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e = new_binary_expr (e->e.expr.op, e->e.expr.e2, e->e.expr.e1);
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} else {
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e = new_unary_expr ('-', e);
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}
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e->e.expr.type = type;
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return fold_constants (e);
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}
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@ -361,8 +373,29 @@ sum_expr (type_t *type, expr_t *a, expr_t *b)
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}
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}
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}
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auto sum = new_binary_expr ('+', a, b);
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bool neg = false;
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if ((is_neg (a) && (is_neg (b) || anti_com (b)))
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|| (anti_com (a) && is_neg (b))) {
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neg = true;
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a = neg_expr (a);
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b = neg_expr (b);
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}
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int op = '+';
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if (is_neg (a) && b->type != ex_extend) {
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auto t = a;
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a = b;
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b = t;
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op = '-';
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b = neg_expr (b);
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} else if (a->type != ex_extend && is_neg (b)) {
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op = '-';
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b = neg_expr (b);
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}
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auto sum = new_binary_expr (op, a, b);
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sum->e.expr.type = type;
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if (neg) {
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sum = neg_expr (sum);
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}
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return sum;
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}
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