Parse and emit `array.len` without a type annotation (#5151)

Test that we can still parse the old annotated form as well.

5 files changed, 15 insertions, 17 deletions

diff --git a/src/passes/Print.cpp b/src/passes/Print.cpp
index 0f4a314ae..d0f19f78e 100644
--- a/src/passes/Print.cpp
+++ b/src/passes/Print.cpp
@@ -2236,14 +2236,7 @@ struct PrintExpressionContents
     printMedium(o, "array.set ");
     TypeNamePrinter(o, wasm).print(curr->ref->type.getHeapType());
   }
-  void visitArrayLen(ArrayLen* curr) {
-    printMedium(o, "array.len ");
-    if (curr->ref->type == Type::unreachable) {
-      TypeNamePrinter(o, wasm).print(HeapType::array);
-    } else {
-      TypeNamePrinter(o, wasm).print(curr->ref->type.getHeapType());
-    }
-  }
+  void visitArrayLen(ArrayLen* curr) { printMedium(o, "array.len"); }
   void visitArrayCopy(ArrayCopy* curr) {
     if (printUnreachableOrNullReplacement(curr->srcRef) ||
         printUnreachableOrNullReplacement(curr->destRef)) {
diff --git a/src/wasm-binary.h b/src/wasm-binary.h
index 709c0c9f9..db123515a 100644
--- a/src/wasm-binary.h
+++ b/src/wasm-binary.h
@@ -1111,8 +1111,9 @@ enum ASTNodes {
   ArrayGetS = 0x14,
   ArrayGetU = 0x15,
   ArraySet = 0x16,
-  ArrayLen = 0x17,
+  ArrayLenAnnotated = 0x17,
   ArrayCopy = 0x18,
+  ArrayLen = 0x19,
   ArrayInitStatic = 0x1a,
   ArrayNew = 0x1b,
   ArrayNewDefault = 0x1c,
diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 13c28f151..54c904459 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -7111,11 +7111,12 @@ bool WasmBinaryBuilder::maybeVisitArraySet(Expression*& out, uint32_t code) {
 }
 
 bool WasmBinaryBuilder::maybeVisitArrayLen(Expression*& out, uint32_t code) {
-  if (code != BinaryConsts::ArrayLen) {
+  if (code == BinaryConsts::ArrayLenAnnotated) {
+    // Ignore the type annotation and don't bother validating it.
+    getU32LEB();
+  } else if (code != BinaryConsts::ArrayLen) {
     return false;
   }
-  // Ignore the type annotation and don't bother validating it.
-  getU32LEB();
   auto* ref = popNonVoidExpression();
   out = Builder(wasm).makeArrayLen(ref);
   return true;
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 41a0619f9..78ac84f42 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -3027,9 +3027,14 @@ Expression* SExpressionWasmBuilder::makeArraySet(Element& s) {
 }
 
 Expression* SExpressionWasmBuilder::makeArrayLen(Element& s) {
-  // Ignore the type annotation and don't bother validating it.
-  parseHeapType(*s[1]);
-  auto ref = parseExpression(*s[2]);
+  // There may or may not be a type annotation.
+  Index i = 1;
+  try {
+    parseHeapType(*s[i]);
+    ++i;
+  } catch (...) {
+  }
+  auto ref = parseExpression(*s[i]);
   return Builder(wasm).makeArrayLen(ref);
 }
 
diff --git a/src/wasm/wasm-stack.cpp b/src/wasm/wasm-stack.cpp
index 7c1c121d5..f30e4be82 100644
--- a/src/wasm/wasm-stack.cpp
+++ b/src/wasm/wasm-stack.cpp
@@ -2169,8 +2169,6 @@ void BinaryInstWriter::visitArraySet(ArraySet* curr) {
 
 void BinaryInstWriter::visitArrayLen(ArrayLen* curr) {
   o << int8_t(BinaryConsts::GCPrefix) << U32LEB(BinaryConsts::ArrayLen);
-  // Unused type index.
-  o << U32LEB(0);
 }
 
 void BinaryInstWriter::visitArrayCopy(ArrayCopy* curr) {