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-rw-r--r--src/emscripten-optimizer/simple_ast.cpp61
-rw-r--r--src/emscripten-optimizer/simple_ast.h9
-rw-r--r--src/tools/wasm2js.cpp125
3 files changed, 125 insertions, 70 deletions
diff --git a/src/emscripten-optimizer/simple_ast.cpp b/src/emscripten-optimizer/simple_ast.cpp
index d6dc5e51a..7575cc6f7 100644
--- a/src/emscripten-optimizer/simple_ast.cpp
+++ b/src/emscripten-optimizer/simple_ast.cpp
@@ -183,65 +183,4 @@ void dump(const char *str, Ref node, bool pretty) {
std::cerr << std::endl;
}
-// Traversals
-
-struct TraverseInfo {
- TraverseInfo() = default;
- TraverseInfo(Ref node) : node(node) {
- assert(node.get());
- if (node->isArray()) {
- for (size_t i = 0; i < node->size(); i++) {
- maybeAdd(node[i]);
- }
- } else if (node->isAssign()) {
- auto assign = node->asAssign();
- maybeAdd(assign->target());
- maybeAdd(assign->value());
- } else if (node->isAssignName()) {
- auto assign = node->asAssignName();
- maybeAdd(assign->value());
- } else {
- // no children
- }
- }
- Ref node;
- size_t index = -1;
- std::vector<Ref> children;
-
-private:
- void maybeAdd(Ref child) {
- if (child.get()) {
- children.push_back(child);
- }
- }
-};
-
-// Traverse, calling visit after the children
-void traversePost(Ref node, std::function<void (Ref)> visit) {
- std::vector<TraverseInfo> stack;
- stack.push_back(TraverseInfo(node));
- while (!stack.empty()) {
- TraverseInfo& back = stack.back();
- if (back.index == size_t(-1)) {
- // This is the first time we see this. Push its children.
- back.index = 0;
- for (auto child : back.children) {
- stack.emplace_back(child);
- }
- continue;
- }
- if (back.index < back.children.size()) {
- // Visit this child.
- back.index++;
- visit(back.children[back.index - 1]);
- continue;
- }
- assert(back.index == back.children.size());
- // Time to visit the node itself
- auto node = back.node;
- stack.pop_back();
- visit(node);
- }
-}
-
} // namespace cashew
diff --git a/src/emscripten-optimizer/simple_ast.h b/src/emscripten-optimizer/simple_ast.h
index 30ef42711..81d20e612 100644
--- a/src/emscripten-optimizer/simple_ast.h
+++ b/src/emscripten-optimizer/simple_ast.h
@@ -394,6 +394,10 @@ struct Value {
return arr->size();
}
+ bool empty() {
+ return size() == 0;
+ }
+
void setSize(size_t size) {
assert(isArray());
auto old = arr->size();
@@ -525,11 +529,6 @@ struct AssignName : public Value {
}
};
-// AST traversals
-
-// Traverse, calling visit after the children
-void traversePost(Ref node, std::function<void (Ref)> visit);
-
// JS printing support
struct JSPrinter {
diff --git a/src/tools/wasm2js.cpp b/src/tools/wasm2js.cpp
index 34ed2d9cb..84aa9f024 100644
--- a/src/tools/wasm2js.cpp
+++ b/src/tools/wasm2js.cpp
@@ -67,19 +67,79 @@ static void printJS(Ref ast, T& output) {
output << jser.buffer << std::endl;
}
+
+// Traversals
+
+struct TraverseInfo {
+ TraverseInfo() = default;
+ TraverseInfo(Ref node) : node(node) {
+ assert(node.get());
+ if (node->isArray()) {
+ for (size_t i = 0; i < node->size(); i++) {
+ maybeAdd(node[i]);
+ }
+ } else if (node->isAssign()) {
+ auto assign = node->asAssign();
+ maybeAdd(assign->target());
+ maybeAdd(assign->value());
+ } else if (node->isAssignName()) {
+ auto assign = node->asAssignName();
+ maybeAdd(assign->value());
+ } else {
+ // no children
+ }
+ }
+ Ref node;
+ bool scanned = false;
+ std::vector<Ref> children;
+
+private:
+ void maybeAdd(Ref child) {
+ if (child.get()) {
+ children.push_back(child);
+ }
+ }
+};
+
+// Traverse, calling visit after the children
+static void traversePrePost(Ref node, std::function<void (Ref)> visitPre, std::function<void (Ref)> visitPost) {
+ std::vector<TraverseInfo> stack;
+ stack.push_back(TraverseInfo(node));
+ while (!stack.empty()) {
+ TraverseInfo& back = stack.back();
+ if (!back.scanned) {
+ back.scanned = true;
+ // This is the first time we see this.
+ visitPre(back.node);
+ for (auto child : back.children) {
+ stack.emplace_back(child);
+ }
+ continue;
+ }
+ // Time to post-visit the node itself
+ auto node = back.node;
+ stack.pop_back();
+ visitPost(node);
+ }
+}
+
+static void traversePost(Ref node, std::function<void (Ref)> visit) {
+ traversePrePost(node, [](Ref node) {}, visit);
+}
+
static void optimizeJS(Ref ast) {
// helpers
auto isOrZero = [](Ref node) {
- return node->isArray() && node->size() > 0 && node[0] == BINARY && node[1] == OR && node[3]->isNumber() && node[3]->getNumber() == 0;
+ return node->isArray() && !node->empty() && node[0] == BINARY && node[1] == OR && node[3]->isNumber() && node[3]->getNumber() == 0;
};
auto isPlus = [](Ref node) {
- return node->isArray() && node->size() > 0 && node[0] == UNARY_PREFIX && node[1] == PLUS;
+ return node->isArray() && !node->empty() && node[0] == UNARY_PREFIX && node[1] == PLUS;
};
auto isBitwise = [](Ref node) {
- if (node->isArray() && node->size() > 0 && node[0] == BINARY) {
+ if (node->isArray() && !node->empty() && node[0] == BINARY) {
auto op = node[1];
return op == OR || op == AND || op == XOR || op == RSHIFT || op == TRSHIFT || op == LSHIFT;
}
@@ -88,7 +148,7 @@ static void optimizeJS(Ref ast) {
// x >> 0 => x | 0
traversePost(ast, [](Ref node) {
- if (node->isArray() && node->size() > 0 && node[0] == BINARY && node[1] == RSHIFT && node[3]->isNumber()) {
+ if (node->isArray() && !node->empty() && node[0] == BINARY && node[1] == RSHIFT && node[3]->isNumber()) {
if (node[3]->getNumber() == 0) {
node[1]->setString(OR);
}
@@ -124,6 +184,63 @@ static void optimizeJS(Ref ast) {
}
}
});
+
+ // Remove unnecessary break/continue labels, when referring to the top level.
+
+ // XXX IString invalid("__wasm2js$INVALID_LABEL__");
+ std::vector<Ref> breakCapturers;
+ std::vector<Ref> continueCapturers;
+ std::unordered_map<IString, Ref> labelToValue; // maps the label to the loop/etc.
+ std::unordered_set<Value*> labelled; // all things with a label on them.
+ Value INVALID;
+ traversePrePost(ast, [&](Ref node) {
+ if (node->isArray() && !node->empty()) {
+ if (node[0] == LABEL) {
+ auto label = node[1]->getIString();
+ labelToValue[label] = node[2];
+ labelled.insert(node[2].get());
+ } else if (node[0] == WHILE || node[0] == DO || node[0] == FOR) {
+ breakCapturers.push_back(node);
+ continueCapturers.push_back(node);
+ } else if (node[0] == cashew::BLOCK) {
+ if (labelled.count(node.get())) {
+ // Cannot break to a block without the label.
+ breakCapturers.push_back(Ref(&INVALID));
+ }
+ } else if (node[0] == SWITCH) {
+ breakCapturers.push_back(node);
+ }
+ }
+ }, [&](Ref node) {
+ if (node->isArray() && !node->empty()) {
+ if (node[0] == LABEL) {
+ auto label = node[1]->getIString();
+ labelToValue.erase(label);
+ labelled.erase(node[2].get());
+ } else if (node[0] == WHILE || node[0] == DO || node[0] == FOR) {
+ breakCapturers.pop_back();
+ continueCapturers.pop_back();
+ } else if (node[0] == cashew::BLOCK) {
+ if (labelled.count(node.get())) {
+ breakCapturers.pop_back();
+ }
+ } else if (node[0] == SWITCH) {
+ breakCapturers.pop_back();
+ } else if (node[0] == BREAK || node[0] == CONTINUE) {
+ if (!node[1]->isNull()) {
+ auto label = node[1]->getIString();
+ assert(labelToValue.count(label));
+ auto& capturers = node[0] == BREAK ? breakCapturers : continueCapturers;
+ assert(!capturers.empty());
+ if (capturers.back() == labelToValue[label]) {
+ // Success, the break/continue goes exactly where we would if we
+ // didn't have the label!
+ node[1]->setNull();
+ }
+ }
+ }
+ }
+ });
}
static void emitWasm(Module& wasm, Output& output, Wasm2JSBuilder::Flags flags, PassOptions options, Name name) {
generated by cgit v1.2.3 (git 2.39.1) at 2025-04-08 11:13:38 +0000