[IRGen] alloc_stack may allocate pack metadata.

When it's a tuple containing a pack.

Author: nate-chandler

lib/SIL/IR/SILInstruction.cpp

@@ -1322,6 +1322,10 @@ bool SILInstruction::mayRequirePackMetadata() const {
   {
     return getOperand(0)->getType().hasPack();
   }
+  case SILInstructionKind::AllocStackInst: {
+    auto *asi = cast<AllocStackInst>(this);
+    return asi->getType().hasPack();
+  }
   case SILInstructionKind::MetatypeInst: {
     auto *mi = cast<MetatypeInst>(this);
     return mi->getType().hasPack();

test/IRGen/pack_marker_insertion.swift

@@ -0,0 +1,6 @@
+// RUN: %target-swift-frontend -emit-ir %s
+
+// Verify that we don't hit the `Instruction missing on-stack pack metadata cleanups!` assertion.
+
+// For alloc_stacks of tuples featuring a pack.
+public func tupleExpansionWithMemberType<each T: Sequence>(seqs: (repeat each T), elts: (repeat (each T).Element)) {}