Skip to content

Binaryen-related micro optimizations #8257

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
stevenwdv wants to merge 6 commits into
base: main
Choose a base branch
from
Open

Binaryen-related micro optimizations #8257

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
6 commits
Select commit Hold shift + click to select a range
04cc0b8
Binaryen-related micro optimizations
stevenwdv Jan 31, 2026
3d9b47c
Revert section Name optimizations
stevenwdv Feb 2, 2026
be94a34
dwarf2yaml.cpp: Add clarified comment from upstream PR
stevenwdv Feb 2, 2026
e756dd1
wasm-debug.cpp: Dot-terminate comment.
stevenwdv Feb 2, 2026
afc8900
wasm-debug.cpp: Code style
stevenwdv Feb 4, 2026
2be3660
Remove now-unused LocationUpdater::hasOld*
stevenwdv Feb 6, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
160 changes: 79 additions & 81 deletions src/wasm/wasm-debug.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -290,36 +290,36 @@ struct LineState {
// FIXME: look at AddrSize on the Unit.
auto item = makeItem(llvm::dwarf::DW_LNE_set_address, 5);
item.Data = addr;
newOpcodes.push_back(item);
newOpcodes.push_back(std::move(item));
}
if (line != old.line && !useSpecial) {
auto item = makeItem(llvm::dwarf::DW_LNS_advance_line);
// In wasm32 we have 32-bit addresses, and the delta here might be
// negative (note that SData is 64-bit, as LLVM supports 64-bit
// addresses too).
item.SData = int32_t(line - old.line);
newOpcodes.push_back(item);
newOpcodes.push_back(std::move(item));
}
if (col != old.col) {
auto item = makeItem(llvm::dwarf::DW_LNS_set_column);
item.Data = col;
newOpcodes.push_back(item);
newOpcodes.push_back(std::move(item));
}
if (file != old.file) {
auto item = makeItem(llvm::dwarf::DW_LNS_set_file);
item.Data = file;
newOpcodes.push_back(item);
newOpcodes.push_back(std::move(item));
}
if (isa != old.isa) {
auto item = makeItem(llvm::dwarf::DW_LNS_set_isa);
item.Data = isa;
newOpcodes.push_back(item);
newOpcodes.push_back(std::move(item));
}
if (discriminator != old.discriminator) {
// len = 1 (subopcode) + 4 (wasm32 address)
auto item = makeItem(llvm::dwarf::DW_LNE_set_discriminator, 5);
item.Data = discriminator;
newOpcodes.push_back(item);
newOpcodes.push_back(std::move(item));
}
if (isStmt != old.isStmt) {
newOpcodes.push_back(makeItem(llvm::dwarf::DW_LNS_negate_stmt));
Expand Down Expand Up @@ -391,6 +391,19 @@ struct AddrExprMap {

// Construct the map from the binaryLocations loaded from the wasm.
AddrExprMap(const Module& wasm) {
size_t numExprs = 0, numDelims = 0;
for (const auto& func : wasm.functions) {
numExprs += func->expressionLocations.size();

for (const auto& [_, delim] : func->delimiterLocations) {
// May be a little large if 0-delimiters exist.
numDelims += delim.size();
}
}
startMap.reserve(numExprs);
endMap.reserve(numExprs);
delimiterMap.reserve(numDelims);

for (auto& func : wasm.functions) {
for (auto& [expr, span] : func->expressionLocations) {
add(expr, span);
Expand Down Expand Up @@ -427,18 +440,22 @@ struct AddrExprMap {

private:
void add(Expression* expr, const BinaryLocations::Span span) {
assert(startMap.count(span.start) == 0);
startMap[span.start] = expr;
assert(endMap.count(span.end) == 0);
endMap[span.end] = expr;
{
[[maybe_unused]] auto [_, inserted] = startMap.emplace(span.start, expr);
assert(inserted);
}
{
[[maybe_unused]] auto [_, inserted] = endMap.emplace(span.end, expr);
assert(inserted);
}
}

void add(Expression* expr,
const BinaryLocations::DelimiterLocations& delimiter) {
for (Index i = 0; i < delimiter.size(); i++) {
if (delimiter[i] != 0) {
assert(delimiterMap.count(delimiter[i]) == 0);
delimiterMap[delimiter[i]] = DelimiterInfo{expr, i};
[[maybe_unused]] auto [_, inserted] = delimiterMap.emplace(delimiter[i], DelimiterInfo{expr, i});
assert(inserted);
}
}
}
Expand Down Expand Up @@ -530,10 +547,6 @@ struct LocationUpdater {
return 0;
}

bool hasOldExprStart(BinaryLocation oldAddr) const {
return oldExprAddrMap.getStart(oldAddr);
}

BinaryLocation getNewExprEnd(BinaryLocation oldAddr) const {
if (auto* expr = oldExprAddrMap.getEnd(oldAddr)) {
auto iter = newLocations.expressions.find(expr);
Expand All @@ -544,10 +557,6 @@ struct LocationUpdater {
return 0;
}

bool hasOldExprEnd(BinaryLocation oldAddr) const {
return oldExprAddrMap.getEnd(oldAddr);
}

BinaryLocation getNewFuncStart(BinaryLocation oldAddr) const {
if (auto* func = oldFuncAddrMap.getStart(oldAddr)) {
// The function might have been optimized away, check.
Expand All @@ -567,10 +576,6 @@ struct LocationUpdater {
return 0;
}

bool hasOldFuncStart(BinaryLocation oldAddr) const {
return oldFuncAddrMap.getStart(oldAddr);
}

BinaryLocation getNewFuncEnd(BinaryLocation oldAddr) const {
if (auto* func = oldFuncAddrMap.getEnd(oldAddr)) {
// The function might have been optimized away, check.
Expand All @@ -590,19 +595,6 @@ struct LocationUpdater {
return 0;
}

// Check for either the end opcode, or one past the end.
bool hasOldFuncEnd(BinaryLocation oldAddr) const {
return oldFuncAddrMap.getEnd(oldAddr);
}

// Check specifically for the end opcode.
bool hasOldFuncEndOpcode(BinaryLocation oldAddr) const {
if (auto* func = oldFuncAddrMap.getEnd(oldAddr)) {
return oldAddr == func->funcLocation.end - 1;
}
return false;
}

BinaryLocation getNewDelimiter(BinaryLocation oldAddr) const {
auto info = oldExprAddrMap.getDelimiter(oldAddr);
if (info.expr) {
Expand All @@ -614,31 +606,31 @@ struct LocationUpdater {
return 0;
}

bool hasOldDelimiter(BinaryLocation oldAddr) const {
return oldExprAddrMap.getDelimiter(oldAddr).expr;
}

// getNewStart|EndAddr utilities.
// TODO: should we track the start and end of delimiters, even though they
// are just one byte?
BinaryLocation getNewStart(BinaryLocation oldStart) const {
if (hasOldExprStart(oldStart)) {
return getNewExprStart(oldStart);
} else if (hasOldFuncStart(oldStart)) {
return getNewFuncStart(oldStart);
} else if (hasOldDelimiter(oldStart)) {
return getNewDelimiter(oldStart);
if (auto loc = getNewExprStart(oldStart)) {
return loc;
}
if (auto loc = getNewFuncStart(oldStart)) {
return loc;
}
if (auto loc = getNewDelimiter(oldStart)) {
return loc;
}
return 0;
}

BinaryLocation getNewEnd(BinaryLocation oldEnd) const {
if (hasOldExprEnd(oldEnd)) {
return getNewExprEnd(oldEnd);
} else if (hasOldFuncEnd(oldEnd)) {
return getNewFuncEnd(oldEnd);
} else if (hasOldDelimiter(oldEnd)) {
return getNewDelimiter(oldEnd);
if (auto loc = getNewExprEnd(oldEnd)) {
return loc;
}
if (auto loc = getNewFuncEnd(oldEnd)) {
return loc;
}
if (auto loc = getNewDelimiter(oldEnd)) {
return loc;
}
return 0;
}
Expand Down Expand Up @@ -706,21 +698,21 @@ static void updateDebugLines(llvm::DWARFYAML::Data& data,
// it away.
BinaryLocation oldAddr = state.addr;
BinaryLocation newAddr = 0;
if (locationUpdater.hasOldExprStart(oldAddr)) {
newAddr = locationUpdater.getNewExprStart(oldAddr);
if (auto loc = locationUpdater.getNewExprStart(oldAddr)) {
newAddr = loc;
}
// Test for a function's end address first, as LLVM output appears to
// use 1-past-the-end-of-the-function as a location in that function,
// and not the next (but the first byte of the next function, which is
// ambiguously identical to that value, is used at least in low_pc).
else if (locationUpdater.hasOldFuncEnd(oldAddr)) {
newAddr = locationUpdater.getNewFuncEnd(oldAddr);
} else if (locationUpdater.hasOldFuncStart(oldAddr)) {
newAddr = locationUpdater.getNewFuncStart(oldAddr);
} else if (locationUpdater.hasOldDelimiter(oldAddr)) {
newAddr = locationUpdater.getNewDelimiter(oldAddr);
} else if (locationUpdater.hasOldExprEnd(oldAddr)) {
newAddr = locationUpdater.getNewExprEnd(oldAddr);
else if ((loc = locationUpdater.getNewFuncEnd(oldAddr))) {
newAddr = loc;
} else if ((loc = locationUpdater.getNewFuncStart(oldAddr))) {
newAddr = loc;
} else if ((loc = locationUpdater.getNewDelimiter(oldAddr))) {
newAddr = loc;
} else if ((loc = locationUpdater.getNewExprEnd(oldAddr))) {
newAddr = loc;
}
if (newAddr && state.needToEmit()) {
// LLVM sometimes emits the same address more than once. We should
Expand Down Expand Up @@ -1075,36 +1067,42 @@ static void updateLoc(llvm::DWARFYAML::Data& yaml,
}

void writeDWARFSections(Module& wasm, const BinaryLocations& newLocations) {
BinaryenDWARFInfo info(wasm);

// Convert to Data representation, which YAML can use to write.
llvm::DWARFYAML::Data data;
if (dwarf2yaml(*info.context, data)) {
Fatal() << "Failed to parse DWARF to YAML";
}
llvm::StringMap<std::unique_ptr<llvm::MemoryBuffer>> newSections;
{
BinaryenDWARFInfo info(wasm);

// Convert to Data representation, which YAML can use to write.
llvm::DWARFYAML::Data data;
if (dwarf2yaml(*info.context, data)) {
Fatal() << "Failed to parse DWARF to YAML";
}

LocationUpdater locationUpdater(wasm, newLocations);
{
LocationUpdater locationUpdater(wasm, newLocations);

updateDebugLines(data, locationUpdater);
updateDebugLines(data, locationUpdater);

bool is64 = wasm.memories.size() > 0 ? wasm.memories[0]->is64() : false;
updateCompileUnits(info, data, locationUpdater, is64);
bool is64 = wasm.memories.size() > 0 ? wasm.memories[0]->is64() : false;
updateCompileUnits(info, data, locationUpdater, is64);

updateRanges(data, locationUpdater);
updateRanges(data, locationUpdater);

updateLoc(data, locationUpdater);
updateLoc(data, locationUpdater);
}

// Convert to binary sections.
auto newSections =
EmitDebugSections(data, false /* EmitFixups for debug_info */);
// Convert to binary sections.
newSections =
EmitDebugSections(data, false /* EmitFixups for debug_info */);
}

// Update the custom sections in the wasm.
// TODO: efficiency
for (auto& section : wasm.customSections) {
if (Name(section.name).startsWith(".debug_")) {
auto llvmName = section.name.substr(1);
if (newSections.count(llvmName)) {
auto llvmData = newSections[llvmName]->getBuffer();
auto it = newSections.find(llvmName);
if (it != newSections.end()) {
auto llvmData = it->second->getBuffer();
section.data.resize(llvmData.size());
std::copy(llvmData.begin(), llvmData.end(), section.data.data());
}
Expand Down
Loading