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/*
* Copyright 2024 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.
*/
//
// DebugLocationPropagation aim to pass debug location from parents or
// previous siblings to expression which has no debug location. This is
// useful for compilers that use Binaryen API to generate WebAssembly modules.
//
#include "pass.h"
#include "wasm-traversal.h"
#include "wasm.h"
#include <cassert>
#include <unordered_map>
namespace wasm {
struct DebugLocationPropagation
: WalkerPass<PostWalker<DebugLocationPropagation>> {
// The top element of this stack is the previous sibling or parent of the
// current expression in `doPrevisit`. To maintain this invariant, expressions
// are only popped once we are done visiting their parents.
ExpressionStack expressionStack;
using Super = WalkerPass<PostWalker<DebugLocationPropagation>>;
bool isFunctionParallel() override { return true; }
bool modifiesBinaryenIR() override { return false; }
bool requiresNonNullableLocalFixups() override { return false; }
void runOnFunction(Module* module, Function* func) override {
if (!func->debugLocations.empty()) {
Super::runOnFunction(module, func);
}
}
Expression* getPrevious() {
if (expressionStack.empty()) {
return nullptr;
}
assert(expressionStack.size() >= 1);
return expressionStack[expressionStack.size() - 1];
}
static void doPreVisit(DebugLocationPropagation* self, Expression** currp) {
auto* curr = *currp;
auto& locs = self->getFunction()->debugLocations;
auto& expressionStack = self->expressionStack;
if (locs.find(curr) == locs.end()) {
// No debug location, see if we should inherit one.
if (auto* previous = self->getPrevious()) {
if (auto it = locs.find(previous); it != locs.end()) {
locs[curr] = it->second;
}
} else if (self->getFunction()->prologLocation.size()) {
// Instructions may inherit their locations from the function
// prolog.
locs[curr] = *self->getFunction()->prologLocation.begin();
}
}
expressionStack.push_back(curr);
}
static void doPostVisit(DebugLocationPropagation* self, Expression** currp) {
auto& exprStack = self->expressionStack;
while (exprStack.back() != *currp) {
// pop all the child expressions and keep current expression in stack.
exprStack.pop_back();
}
// the stack should never be empty
assert(!exprStack.empty());
}
static void scan(DebugLocationPropagation* self, Expression** currp) {
self->pushTask(DebugLocationPropagation::doPostVisit, currp);
PostWalker<DebugLocationPropagation>::scan(self, currp);
self->pushTask(DebugLocationPropagation::doPreVisit, currp);
}
std::unique_ptr<Pass> create() override {
return std::make_unique<DebugLocationPropagation>();
}
};
Pass* createDebugLocationPropagationPass() {
return new DebugLocationPropagation();
}
} // namespace wasm
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