Tuple globals (#2718)

Since it wasn't easy to support tuples in Asyncify's call support
using temporary functions, we decided to allow tuple-typed globals
after all. This PR adds support for parsing, printing, lowering, and
interpreting tuple globals and also adds validation ensuring that
imported and exported globals do not have tuple types.

1 files changed, 21 insertions, 2 deletions

diff --git a/src/ir/module-utils.h b/src/ir/module-utils.h
index be924f742..485bc4833 100644
--- a/src/ir/module-utils.h
+++ b/src/ir/module-utils.h
@@ -35,8 +35,8 @@ namespace ModuleUtils {
 // just use them directly).
 struct BinaryIndexes {
   std::unordered_map<Name, Index> functionIndexes;
-  std::unordered_map<Name, Index> globalIndexes;
   std::unordered_map<Name, Index> eventIndexes;
+  std::unordered_map<Name, Index> globalIndexes;
 
   BinaryIndexes(Module& wasm) {
     auto addIndexes = [&](auto& source, auto& indexes) {
@@ -56,8 +56,27 @@ struct BinaryIndexes {
       }
     };
     addIndexes(wasm.functions, functionIndexes);
-    addIndexes(wasm.globals, globalIndexes);
     addIndexes(wasm.events, eventIndexes);
+
+    // Globals may have tuple types in the IR, in which case they lower to
+    // multiple globals, one for each tuple element, in the binary. Tuple
+    // globals therefore occupy multiple binary indices, and we have to take
+    // that into account when calculating indices.
+    Index globalCount = 0;
+    auto addGlobal = [&](auto* curr) {
+      globalIndexes[curr->name] = globalCount;
+      globalCount += curr->type.size();
+    };
+    for (auto& curr : wasm.globals) {
+      if (curr->imported()) {
+        addGlobal(curr.get());
+      }
+    }
+    for (auto& curr : wasm.globals) {
+      if (!curr->imported()) {
+        addGlobal(curr.get());
+      }
+    }
   }
 };