Represent dylink section in IR, so we can update it. (#2715)

Update it from wasm-emscripten-finalize when we append
to the table.

1 files changed, 43 insertions, 13 deletions

diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 8d9696aa2..c36789828 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -38,7 +38,7 @@ void WasmBinaryWriter::prepare() {
 void WasmBinaryWriter::write() {
   writeHeader();
 
-  writeEarlyUserSections();
+  writeDylinkSection();
 
   initializeDebugInfo();
   if (sourceMap) {
@@ -632,16 +632,6 @@ void WasmBinaryWriter::writeSourceMapEpilog() {
   *sourceMap << "\"}";
 }
 
-void WasmBinaryWriter::writeEarlyUserSections() {
-  // The dylink section must be the first in the module, per
-  // the spec, to allow simple parsing by loaders.
-  for (auto& section : wasm->userSections) {
-    if (section.name == BinaryConsts::UserSections::Dylink) {
-      writeUserSection(section);
-    }
-  }
-}
-
 void WasmBinaryWriter::writeLateUserSections() {
   for (auto& section : wasm->userSections) {
     if (section.name != BinaryConsts::UserSections::Dylink) {
@@ -707,6 +697,24 @@ void WasmBinaryWriter::writeFeaturesSection() {
   finishSection(start);
 }
 
+void WasmBinaryWriter::writeDylinkSection() {
+  if (!wasm->dylinkSection) {
+    return;
+  }
+
+  auto start = startSection(BinaryConsts::User);
+  writeInlineString(BinaryConsts::UserSections::Dylink);
+  o << U32LEB(wasm->dylinkSection->memorySize);
+  o << U32LEB(wasm->dylinkSection->memoryAlignment);
+  o << U32LEB(wasm->dylinkSection->tableSize);
+  o << U32LEB(wasm->dylinkSection->tableAlignment);
+  o << U32LEB(wasm->dylinkSection->neededDynlibs.size());
+  for (auto& neededDynlib : wasm->dylinkSection->neededDynlibs) {
+    writeInlineString(neededDynlib.c_str());
+  }
+  finishSection(start);
+}
+
 void WasmBinaryWriter::writeDebugLocation(const Function::DebugLocation& loc) {
   if (loc == lastDebugLocation) {
     return;
@@ -963,6 +971,8 @@ void WasmBinaryBuilder::readUserSection(size_t payloadLen) {
     readNames(payloadLen);
   } else if (sectionName.equals(BinaryConsts::UserSections::TargetFeatures)) {
     readFeatures(payloadLen);
+  } else if (sectionName.equals(BinaryConsts::UserSections::Dylink)) {
+    readDylink(payloadLen);
   } else {
     // an unfamiliar custom section
     if (sectionName.equals(BinaryConsts::UserSections::Linking)) {
@@ -2122,8 +2132,8 @@ void WasmBinaryBuilder::readFeatures(size_t payloadLen) {
   wasm.features = FeatureSet::MVP;
 
   auto sectionPos = pos;
-  size_t num_feats = getU32LEB();
-  for (size_t i = 0; i < num_feats; ++i) {
+  size_t numFeatures = getU32LEB();
+  for (size_t i = 0; i < numFeatures; ++i) {
     uint8_t prefix = getInt8();
     if (prefix != BinaryConsts::FeatureUsed) {
       if (prefix == BinaryConsts::FeatureRequired) {
@@ -2171,6 +2181,26 @@ void WasmBinaryBuilder::readFeatures(size_t payloadLen) {
   }
 }
 
+void WasmBinaryBuilder::readDylink(size_t payloadLen) {
+  wasm.dylinkSection = make_unique<DylinkSection>();
+
+  auto sectionPos = pos;
+
+  wasm.dylinkSection->memorySize = getU32LEB();
+  wasm.dylinkSection->memoryAlignment = getU32LEB();
+  wasm.dylinkSection->tableSize = getU32LEB();
+  wasm.dylinkSection->tableAlignment = getU32LEB();
+
+  size_t numNeededDynlibs = getU32LEB();
+  for (size_t i = 0; i < numNeededDynlibs; ++i) {
+    wasm.dylinkSection->neededDynlibs.push_back(getInlineString());
+  }
+
+  if (pos != sectionPos + payloadLen) {
+    throwError("bad features section size");
+  }
+}
+
 BinaryConsts::ASTNodes WasmBinaryBuilder::readExpression(Expression*& curr) {
   if (pos == endOfFunction) {
     throwError("Reached function end without seeing End opcode");