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Generalize EM_JS parsing code. #2233

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Merged
merged 1 commit into from
Jul 18, 2019
Merged

Generalize EM_JS parsing code. #2233

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33 changes: 6 additions & 27 deletions src/wasm/wasm-emscripten.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -741,35 +741,14 @@ struct EmJsWalker : public PostWalker<EmJsWalker> {
return;
}
auto funcName = std::string(curr->name.stripPrefix(EM_JS_PREFIX.str));
auto addrConst = curr->body->dynCast<Const>();
if (addrConst == nullptr) {
auto block = curr->body->dynCast<Block>();
Expression* value = nullptr;
if (block && block->list.size() > 0) {
value = block->list[0];
// first item may be a set of a local that we get later
auto* set = value->dynCast<LocalSet>();
if (set) {
value = block->list[1];
}
// look into a return value
if (auto* ret = value->dynCast<Return>()) {
value = ret->value;
}
// if it's a get of that set, use that value
if (auto* get = value->dynCast<LocalGet>()) {
if (set && get->index == set->index) {
value = set->value;
}
}
}
if (value) {
addrConst = value->dynCast<Const>();
}
}
if (addrConst == nullptr) {
// An EM_JS has a single const in the body. Typically it is just returned,
// but in unoptimized code it might be stored to a local and loaded from
// there, and in relocatable code it might get added to __memory_base etc.
FindAll<Const> consts(curr->body);
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@jgravelle-google jgravelle-google Jul 18, 2019

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Oh man a Const-finder? That's way nicer :D

if (consts.list.size() != 1) {
Fatal() << "Unexpected generated __em_js__ function body: " << curr->name;
}
auto* addrConst = consts.list[0];
auto code = codeForConstAddr(wasm, segmentOffsets, addrConst);
codeByName[funcName] = code;
}
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