Source maps: Allow specifying that an expression has no debug info in text (#6520)

;;@

with nothing else (no source:line) can be used to specify that the following
expression does not have any debug info associated to it. This can be used
to stop the automatic propagation of debug info in the text parsers.

The text printer has also been updated to output this comment when needed.

1 files changed, 40 insertions, 21 deletions

diff --git a/src/wasm/wasm-ir-builder.cpp b/src/wasm/wasm-ir-builder.cpp
index 91e990180..f816d4d1e 100644
--- a/src/wasm/wasm-ir-builder.cpp
+++ b/src/wasm/wasm-ir-builder.cpp
@@ -168,21 +168,37 @@ Result<Expression*> IRBuilder::build() {
   return expr;
 }
 
-void IRBuilder::setDebugLocation(const Function::DebugLocation& loc) {
-  DBG(std::cerr << "setting debugloc " << loc.fileIndex << ":" << loc.lineNumber
-                << ":" << loc.columnNumber << "\n";);
-  debugLoc = loc;
+void IRBuilder::setDebugLocation(
+  const std::optional<Function::DebugLocation>& loc) {
+  if (loc) {
+    DBG(std::cerr << "setting debugloc " << loc->fileIndex << ":"
+                  << loc->lineNumber << ":" << loc->columnNumber << "\n";);
+  } else {
+    DBG(std::cerr << "setting debugloc to none\n";);
+  }
+  if (loc) {
+    debugLoc = *loc;
+  } else {
+    debugLoc = NoDebug();
+  }
 }
 
 void IRBuilder::applyDebugLoc(Expression* expr) {
-  if (debugLoc) {
+  if (!std::get_if<CanReceiveDebug>(&debugLoc)) {
     if (func) {
-      DBG(std::cerr << "applying debugloc " << debugLoc->fileIndex << ":"
-                    << debugLoc->lineNumber << ":" << debugLoc->columnNumber
-                    << " to expression " << ShallowExpression{expr} << "\n");
-      func->debugLocations[expr] = *debugLoc;
+      if (auto* loc = std::get_if<Function::DebugLocation>(&debugLoc)) {
+        DBG(std::cerr << "applying debugloc " << loc->fileIndex << ":"
+                      << loc->lineNumber << ":" << loc->columnNumber
+                      << " to expression " << ShallowExpression{expr} << "\n");
+        func->debugLocations[expr] = *loc;
+      } else {
+        assert(std::get_if<NoDebug>(&debugLoc));
+        DBG(std::cerr << "applying debugloc to expression "
+                      << ShallowExpression{expr} << "\n");
+        func->debugLocations[expr] = std::nullopt;
+      }
     }
-    debugLoc.reset();
+    debugLoc = CanReceiveDebug();
   }
 }
 
@@ -677,10 +693,10 @@ Result<> IRBuilder::visitFunctionStart(Function* func) {
   if (!scopeStack.empty()) {
     return Err{"unexpected start of function"};
   }
-  if (debugLoc) {
-    func->prologLocation.insert(*debugLoc);
-    debugLoc.reset();
+  if (auto* loc = std::get_if<Function::DebugLocation>(&debugLoc)) {
+    func->prologLocation.insert(*loc);
   }
+  debugLoc = CanReceiveDebug();
   scopeStack.push_back(ScopeCtx::makeFunc(func));
   this->func = func;
   return Ok{};
@@ -718,12 +734,13 @@ Result<> IRBuilder::visitTryTableStart(TryTable* trytable, Name label) {
 }
 
 Result<Expression*> IRBuilder::finishScope(Block* block) {
-  if (debugLoc) {
-    DBG(std::cerr << "discarding debugloc " << debugLoc->fileIndex << ":"
-                  << debugLoc->lineNumber << ":" << debugLoc->columnNumber
-                  << "\n");
+#if IR_BUILDER_DEBUG
+  if (auto* loc = std::get_if<Function::DebugLocation>(&debugLoc)) {
+    std::cerr << "discarding debugloc " << loc->fileIndex << ":"
+              << loc->lineNumber << ":" << loc->columnNumber << "\n";
   }
-  debugLoc.reset();
+#endif
+  debugLoc = CanReceiveDebug();
 
   if (scopeStack.empty() || scopeStack.back().isNone()) {
     return Err{"unexpected end of scope"};
@@ -913,10 +930,12 @@ Result<> IRBuilder::visitEnd() {
   if (scope.isNone()) {
     return Err{"unexpected end"};
   }
-  if (auto* func = scope.getFunction(); func && debugLoc) {
-    func->epilogLocation.insert(*debugLoc);
-    debugLoc.reset();
+  if (auto* func = scope.getFunction(); func) {
+    if (auto* loc = std::get_if<Function::DebugLocation>(&debugLoc)) {
+      func->epilogLocation.insert(*loc);
+    }
   }
+  debugLoc = CanReceiveDebug();
   auto expr = finishScope(scope.getBlock());
   CHECK_ERR(expr);