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| // combined SimpleConstProp + Identity + GVN solver. | |
| // returns NULL if it made no progress | |
| Node* peephole_node(Optimizer* opt, Node* n) { | |
| Node* k; | |
| // tries to deduce the value of an op based on the | |
| // types of the inputs, if both inputs were deduced | |
| // constant we'd be constants and if both inputs were | |
| // ranges we might infer extra data if not a constant. | |
| Type* t = value(opt, n); | |
| k = try_as_const(opt, n, t); | |
| if (k) { return k; } | |
| // this is ops which replace the node with a direct | |
| // input (x + 0 => x), because of this we don't need | |
| // to rerun const prop since they don't change nodes | |
| // just referenced existing ones. | |
| // | |
| // identity(opt, n) will always return a node, either n | |
| // or a direct replacement | |
| k = identity(opt, n); | |
| if (k != n) { return k; } | |
| // GVN, we literally just place nodes into a hash table. | |
| // no need to rerun it's ruleset if it's just referencing | |
| // an existing node. | |
| k = hashset_get(opt->gvn_nodes, n); | |
| if (k) { | |
| hashset_put(opt->gvn_nodes, k); | |
| return k; | |
| } | |
| // it's already in it's normal form (no progress) | |
| return NULL; | |
| } | |
| void peephole(Optimizer* opt, Worklist* ws) { | |
| Node* n; | |
| while (n = worklist_pop(ws), n) { | |
| Node* k = peephole_node(ws, n); | |
| if (k != NULL) { | |
| subsume_node(opt, n, k); | |
| worklist_push_users(ws, k); | |
| } | |
| } | |
| } |
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