3 files changed, 65 insertions, 13 deletions

diff --git a/src/ir/ExpressionAnalyzer.cpp b/src/ir/ExpressionAnalyzer.cpp
index 04ef52026..0b0adae9e 100644
--- a/src/ir/ExpressionAnalyzer.cpp
+++ b/src/ir/ExpressionAnalyzer.cpp
@@ -17,6 +17,7 @@
 #include "ir/iteration.h"
 #include "ir/load-utils.h"
 #include "ir/utils.h"
+#include "shared-constants.h"
 #include "support/hash.h"
 #include "support/small_vector.h"
 #include "wasm-traversal.h"
@@ -261,6 +262,9 @@ size_t ExpressionAnalyzer::hash(Expression* curr) {
 
     Hasher(Expression* curr) {
       stack.push_back(curr);
+      // DELEGATE_CALLER_TARGET is a fake target used to denote delegating to
+      // the caller. Add it here to prevent the unknown name error.
+      noteScopeName(DELEGATE_CALLER_TARGET);
 
       while (stack.size() > 0) {
         curr = stack.back();
@@ -327,13 +331,15 @@ size_t ExpressionAnalyzer::hash(Expression* curr) {
       }
     }
     void visitScopeName(Name curr) {
-      // Names are relative, we give the same hash for
-      // (block $x (br $x))
-      // (block $y (br $y))
-      static_assert(sizeof(Index) == sizeof(int32_t),
-                    "wasm64 will need changes here");
-      assert(internalNames.find(curr) != internalNames.end());
-      rehash(digest, internalNames[curr]);
+      if (curr.is()) { // try's delegate target can be null
+        // Names are relative, we give the same hash for
+        // (block $x (br $x))
+        // (block $y (br $y))
+        static_assert(sizeof(Index) == sizeof(int32_t),
+                      "wasm64 will need changes here");
+        assert(internalNames.find(curr) != internalNames.end());
+        rehash(digest, internalNames[curr]);
+      }
     }
     void visitNonScopeName(Name curr) { rehash(digest, uint64_t(curr.str)); }
     void visitType(Type curr) { rehash(digest, curr.getID()); }
diff --git a/src/ir/branch-utils.h b/src/ir/branch-utils.h
index a9561ef07..8a4f02a58 100644
--- a/src/ir/branch-utils.h
+++ b/src/ir/branch-utils.h
@@ -40,9 +40,9 @@ inline bool isBranchReachable(Expression* expr) {
   return true;
 }
 
-// Perform a generic operation on uses of scope names (branch targets) in an
-// expression. The provided function receives a Name& which it can modify if it
-// needs to.
+// Perform a generic operation on uses of scope names (branch + delegate
+// targets) in an expression. The provided function receives a Name& which it
+// can modify if it needs to.
 template<typename T> void operateOnScopeNameUses(Expression* expr, T func) {
 #define DELEGATE_ID expr->_id
 
@@ -83,7 +83,7 @@ void operateOnScopeNameUsesAndSentTypes(Expression* expr, T func) {
     } else if (auto* br = expr->dynCast<BrOn>()) {
       func(name, br->getCastType());
     } else {
-      WASM_UNREACHABLE("bad br type");
+      assert(expr->is<Try>()); // delegate
     }
   });
 }
@@ -135,6 +135,46 @@ inline bool replacePossibleTarget(Expression* branch, Name from, Name to) {
   return worked;
 }
 
+// Replace all delegate targets within the given AST.
+inline void replaceDelegateTargets(Expression* ast, Name from, Name to) {
+  struct Replacer
+    : public PostWalker<Replacer, UnifiedExpressionVisitor<Replacer>> {
+    Name from, to;
+    Replacer(Name from, Name to) : from(from), to(to) {}
+    void visitExpression(Expression* curr) {
+      if (curr->is<Try>()) {
+        operateOnScopeNameUses(curr, [&](Name& name) {
+          if (name == from) {
+            name = to;
+          }
+        });
+      }
+    }
+  };
+  Replacer replacer(from, to);
+  replacer.walk(ast);
+}
+
+// Replace all branch targets within the given AST.
+inline void replaceBranchTargets(Expression* ast, Name from, Name to) {
+  struct Replacer
+    : public PostWalker<Replacer, UnifiedExpressionVisitor<Replacer>> {
+    Name from, to;
+    Replacer(Name from, Name to) : from(from), to(to) {}
+    void visitExpression(Expression* curr) {
+      if (Properties::isBranch(curr)) {
+        operateOnScopeNameUses(curr, [&](Name& name) {
+          if (name == from) {
+            name = to;
+          }
+        });
+      }
+    }
+  };
+  Replacer replacer(from, to);
+  replacer.walk(ast);
+}
+
 // Returns the set of targets to which we branch that are
 // outside of an expression.
 inline NameSet getExitingBranches(Expression* ast) {
diff --git a/src/ir/properties.h b/src/ir/properties.h
index b60c74d98..8ae7befba 100644
--- a/src/ir/properties.h
+++ b/src/ir/properties.h
@@ -69,13 +69,15 @@ inline bool isControlFlowStructure(Expression* curr) {
          curr->is<Try>();
 }
 
-// Check if an expression is a control flow construct with a name,
-// which implies it may have breaks to it.
+// Check if an expression is a control flow construct with a name, which implies
+// it may have breaks or delegates to it.
 inline bool isNamedControlFlow(Expression* curr) {
   if (auto* block = curr->dynCast<Block>()) {
     return block->name.is();
   } else if (auto* loop = curr->dynCast<Loop>()) {
     return loop->name.is();
+  } else if (auto* try_ = curr->dynCast<Try>()) {
+    return try_->name.is();
   }
   return false;
 }
@@ -104,6 +106,10 @@ inline bool isConstantExpression(const Expression* curr) {
   return false;
 }
 
+inline bool isBranch(const Expression* curr) {
+  return curr->is<Break>() || curr->is<Switch>() || curr->is<BrOn>();
+}
+
 inline Literal getLiteral(const Expression* curr) {
   if (auto* c = curr->dynCast<Const>()) {
     return c->value;