Refactor Host expression to MemorySize and MemoryGrow (#3137)

Aligns the internal representations of `memory.size` and `memory.grow` with other more recent memory instructions by removing the legacy `Host` expression class and adding separate expression classes for `MemorySize` and `MemoryGrow`. Simplifies related APIs, but is also a breaking API change.

1 files changed, 20 insertions, 24 deletions

diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 2910bb383..e958dca6e 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -2452,6 +2452,14 @@ BinaryConsts::ASTNodes WasmBinaryBuilder::readExpression(Expression*& curr) {
     case BinaryConsts::BrOnExn:
       visitBrOnExn((curr = allocator.alloc<BrOnExn>())->cast<BrOnExn>());
       break;
+    case BinaryConsts::MemorySize:
+      visitMemorySize(
+        (curr = allocator.alloc<MemorySize>())->cast<MemorySize>());
+      break;
+    case BinaryConsts::MemoryGrow:
+      visitMemoryGrow(
+        (curr = allocator.alloc<MemoryGrow>())->cast<MemoryGrow>());
+      break;
     case BinaryConsts::AtomicPrefix: {
       code = static_cast<uint8_t>(getU32LEB());
       if (maybeVisitLoad(curr, code, /*isAtomic=*/true)) {
@@ -2551,9 +2559,6 @@ BinaryConsts::ASTNodes WasmBinaryBuilder::readExpression(Expression*& curr) {
       if (maybeVisitStore(curr, code, /*isAtomic=*/false)) {
         break;
       }
-      if (maybeVisitHost(curr, code)) {
-        break;
-      }
       throwError("bad node code " + std::to_string(code));
       break;
     }
@@ -4763,32 +4768,23 @@ void WasmBinaryBuilder::visitReturn(Return* curr) {
   curr->finalize();
 }
 
-bool WasmBinaryBuilder::maybeVisitHost(Expression*& out, uint8_t code) {
-  Host* curr;
-  switch (code) {
-    case BinaryConsts::MemorySize: {
-      curr = allocator.alloc<Host>();
-      curr->op = MemorySize;
-      break;
-    }
-    case BinaryConsts::MemoryGrow: {
-      curr = allocator.alloc<Host>();
-      curr->op = MemoryGrow;
-      curr->operands.resize(1);
-      curr->operands[0] = popNonVoidExpression();
-      break;
-    }
-    default:
-      return false;
+void WasmBinaryBuilder::visitMemorySize(MemorySize* curr) {
+  BYN_TRACE("zz node: MemorySize\n");
+  auto reserved = getU32LEB();
+  if (reserved != 0) {
+    throwError("Invalid reserved field on memory.size");
   }
-  BYN_TRACE("zz node: Host\n");
+  curr->finalize();
+}
+
+void WasmBinaryBuilder::visitMemoryGrow(MemoryGrow* curr) {
+  BYN_TRACE("zz node: MemoryGrow\n");
+  curr->delta = popNonVoidExpression();
   auto reserved = getU32LEB();
   if (reserved != 0) {
-    throwError("Invalid reserved field on memory.grow/memory.size");
+    throwError("Invalid reserved field on memory.grow");
   }
   curr->finalize();
-  out = curr;
-  return true;
 }
 
 void WasmBinaryBuilder::visitNop(Nop* curr) { BYN_TRACE("zz node: Nop\n"); }