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/*
* Copyright 2022 WebAssembly Community Group participants
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//
// Handle the computation of global effects. The effects are stored on the
// PassOptions structure; see more details there.
//
#include "ir/module-utils.h"
#include "pass.h"
#include "wasm.h"
namespace wasm {
struct GenerateGlobalEffects : public Pass {
void run(Module* module) override {
// TODO: Full transitive closure of effects. For now, we just look at each
// function by itself.
auto& funcEffectsMap = getPassOptions().funcEffectsMap;
// First, clear any previous effects.
funcEffectsMap.reset();
// When we find useful effects, we'll save them. If we can't find anything,
// the final map we emit will not have an entry there at all.
using PossibleEffects = std::unique_ptr<EffectAnalyzer>;
ModuleUtils::ParallelFunctionAnalysis<PossibleEffects> analysis(
*module, [&](Function* func, PossibleEffects& storedEffects) {
if (func->imported()) {
// Imports can do anything, so we need to assume the worst anyhow,
// which is the same as not specifying any effects for them in the
// map.
return;
}
// Gather the effects.
auto effects =
std::make_unique<EffectAnalyzer>(getPassOptions(), *module, func);
// If the body has a call, give up - that means we can't infer a more
// specific set of effects than the pessimistic case of just assuming
// any call to here is an arbitrary call. (See the TODO above for
// improvements.)
if (effects->calls) {
return;
}
// Save the useful effects we found.
storedEffects = std::move(effects);
});
// Generate the final data structure.
for (auto& [func, possibleEffects] : analysis.map) {
if (possibleEffects) {
// Only allocate a new funcEffectsMap if we actually have data for it
// (which might make later effect computation slightly faster, to
// quickly skip the funcEffectsMap code path).
if (!funcEffectsMap) {
funcEffectsMap = std::make_shared<FuncEffectsMap>();
}
funcEffectsMap->emplace(func->name, *possibleEffects);
}
}
}
};
struct DiscardGlobalEffects : public Pass {
void run(Module* module) override { getPassOptions().funcEffectsMap.reset(); }
};
Pass* createGenerateGlobalEffectsPass() { return new GenerateGlobalEffects(); }
Pass* createDiscardGlobalEffectsPass() { return new DiscardGlobalEffects(); }
} // namespace wasm
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