4 files changed, 15 insertions, 26 deletions

diff --git a/src/wasm.h b/src/wasm.h
index 04e2faeb3..295088780 100644
--- a/src/wasm.h
+++ b/src/wasm.h
@@ -1413,10 +1413,10 @@ struct BinaryLocations {
   // control flow, have, like 'end' for loop and block. We keep these in a
   // separate map because they are rare and we optimize for the storage space
   // for the common type of instruction which just needs a Span. We implement
-  // this as a simple struct with two elements (as two extra elements is the
-  // maximum currently needed; due to 'catch' and 'end' for try-catch). The
-  // second value may be 0, indicating it is not used.
-  struct DelimiterLocations : public std::array<BinaryLocation, 2> {
+  // this as a simple array with one element at the moment (more elements may
+  // be necessary in the future).
+  // TODO: If we are sure we won't need more, make this a single value?
+  struct DelimiterLocations : public std::array<BinaryLocation, 1> {
     DelimiterLocations() {
       // Ensure zero-initialization.
       for (auto& item : *this) {
@@ -1425,14 +1425,7 @@ struct BinaryLocations {
     }
   };
 
-  enum DelimiterId {
-    // All control flow structures have an end, so use index 0 for that.
-    End = 0,
-    // Use index 1 for all other current things.
-    Else = 1,
-    Catch = 1,
-    Invalid = -1
-  };
+  enum DelimiterId { Else = 0, Catch = 0, Invalid = -1 };
   std::unordered_map<Expression*, DelimiterLocations> delimiters;
 
   // DWARF debug info can refer to multiple interesting positions in a function.
diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 5c25fd0d2..0c56af8e0 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -865,7 +865,6 @@ void WasmBinaryWriter::writeDebugLocation(Expression* curr, Function* func) {
 void WasmBinaryWriter::writeDebugLocationEnd(Expression* curr, Function* func) {
   if (func && !func->expressionLocations.empty()) {
     auto& span = binaryLocations.expressions.at(curr);
-    assert(span.end == 0);
     span.end = o.size();
   }
 }
@@ -2580,7 +2579,12 @@ BinaryConsts::ASTNodes WasmBinaryBuilder::readExpression(Expression*& curr) {
       break;
     case BinaryConsts::End:
       curr = nullptr;
-      continueControlFlow(BinaryLocations::End, startPos);
+      // Pop the current control flow structure off the stack. If there is none
+      // then this is the "end" of the function itself, which also emits an
+      // "end" byte.
+      if (!controlFlowStack.empty()) {
+        controlFlowStack.pop_back();
+      }
       break;
     case BinaryConsts::Else:
       curr = nullptr;
@@ -2808,22 +2812,12 @@ void WasmBinaryBuilder::startControlFlow(Expression* curr) {
 void WasmBinaryBuilder::continueControlFlow(BinaryLocations::DelimiterId id,
                                             BinaryLocation pos) {
   if (DWARF && currFunction) {
-    if (controlFlowStack.empty()) {
-      // We reached the end of the function, which is also marked with an
-      // "end", like a control flow structure.
-      assert(id == BinaryLocations::End);
-      assert(pos + 1 == endOfFunction);
-      return;
-    }
     assert(!controlFlowStack.empty());
     auto currControlFlow = controlFlowStack.back();
     // We are called after parsing the byte, so we need to subtract one to
     // get its position.
     currFunction->delimiterLocations[currControlFlow][id] =
       pos - codeSectionLocation;
-    if (id == BinaryLocations::End) {
-      controlFlowStack.pop_back();
-    }
   }
 }
 
diff --git a/src/wasm/wasm-debug.cpp b/src/wasm/wasm-debug.cpp
index 0f37374b5..448bcaaa9 100644
--- a/src/wasm/wasm-debug.cpp
+++ b/src/wasm/wasm-debug.cpp
@@ -680,6 +680,8 @@ static void updateDebugLines(llvm::DWARFYAML::Data& data,
           newAddr = locationUpdater.getNewFuncStart(oldAddr);
         } else if (locationUpdater.hasOldDelimiter(oldAddr)) {
           newAddr = locationUpdater.getNewDelimiter(oldAddr);
+        } else if (locationUpdater.hasOldExprEnd(oldAddr)) {
+          newAddr = locationUpdater.getNewExprEnd(oldAddr);
         }
         if (newAddr && state.needToEmit()) {
           // LLVM sometimes emits the same address more than once. We should
diff --git a/src/wasm/wasm-stack.cpp b/src/wasm/wasm-stack.cpp
index 2ec156eea..1d290f53c 100644
--- a/src/wasm/wasm-stack.cpp
+++ b/src/wasm/wasm-stack.cpp
@@ -1880,10 +1880,10 @@ void BinaryInstWriter::visitArrayLen(ArrayLen* curr) {
 void BinaryInstWriter::emitScopeEnd(Expression* curr) {
   assert(!breakStack.empty());
   breakStack.pop_back();
+  o << int8_t(BinaryConsts::End);
   if (func && !sourceMap) {
-    parent.writeExtraDebugLocation(curr, func, BinaryLocations::End);
+    parent.writeDebugLocationEnd(curr, func);
   }
-  o << int8_t(BinaryConsts::End);
 }
 
 void BinaryInstWriter::emitFunctionEnd() { o << int8_t(BinaryConsts::End); }