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// combined "Peeps + ConstProp + GVN" solver (extended version of the one in Combining Analyses, Combining Optimizations 7.3.2) | |
// | |
// returns isomorphic node (might be the same node). | |
Node* peephole_node(Optimizer* opt, Node* n) { | |
Node* k; | |
bool progress = false; | |
// potential mutations from ideal() means we need to get rehash. | |
hashset_remove(opt->gvn_nodes, n); | |
// iterative convergence (rewrite peepholes): | |
// we'll settle on a fixpoint and be happy. | |
while (k = ideal(n), k) { n = k; } | |
// tries to deduce the value of an op based on the | |
// types of the inputs, if both inputs were deduced | |
// constant we might be constant 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 (which are either in | |
// normal form or waiting on the worklist). | |
// | |
// 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; | |
} | |
return n; | |
} |
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