Make shader generation more deterministic by removing a sort of pointers.
authorSteinar H. Gunderson <sgunderson@bigfoot.com>
Thu, 24 Dec 2015 15:43:23 +0000 (16:43 +0100)
committerSteinar H. Gunderson <sgunderson@bigfoot.com>
Thu, 24 Dec 2015 15:43:23 +0000 (16:43 +0100)
effect_chain.cpp

index c2402da..30dc3e4 100644 (file)
@@ -589,9 +589,17 @@ Phase *EffectChain::construct_phase(Node *output, map<Node *, Phase *> *complete
        // and create a GLSL program for it.
        assert(!phase->effects.empty());
 
-       // Deduplicate the inputs.
-       sort(phase->inputs.begin(), phase->inputs.end());
-       phase->inputs.erase(unique(phase->inputs.begin(), phase->inputs.end()), phase->inputs.end());
+       // Deduplicate the inputs, but don't change the ordering e.g. by sorting;
+       // that would be nondeterministic and thus reduce cacheability.
+       // TODO: Make this even more deterministic.
+       vector<Phase *> dedup_inputs;
+       set<Phase *> seen_inputs;
+       for (size_t i = 0; i < phase->inputs.size(); ++i) {
+               if (seen_inputs.insert(phase->inputs[i]).second) {
+                       dedup_inputs.push_back(phase->inputs[i]);
+               }
+       }
+       swap(phase->inputs, dedup_inputs);
 
        // Allocate samplers for each input.
        phase->input_samplers.resize(phase->inputs.size());