[IRGen] Insts with packs in ops/results may alloc.

Instead of assuming that the list of instructions known to allocate pack
metadata is exhaustive and returning false from mayRequirePackMetadata
for all others, consider the types of the results and operands of other
instructions and look for packs.

Author: nate-chandler

lib/IRGen/PackMetadataMarkerInserter.cpp

@@ -91,7 +91,7 @@ Inserter::shouldInsertMarkersForInstruction(SILInstruction *inst) {
             BuiltinValueKind::StartAsyncLetWithLocalBuffer ||
         bi->getBuiltinKind() == BuiltinValueKind::StartAsyncLet)
       return Inserter::FindResult::Unhandleable;
-    return Inserter::FindResult::None;
+    LLVM_FALLTHROUGH;
   }
   default:
     return inst->mayRequirePackMetadata() ? FindResult::Some : FindResult::None;

lib/SIL/IR/SILInstruction.cpp

@@ -1336,6 +1336,27 @@ bool SILInstruction::mayRequirePackMetadata() const {
     return ty->hasAnyPack();
   }
   default:
+    // Instructions that deallocate stack must not result in pack metadata
+    // materialization.  If they did there would be no way to create the pack
+    // metadata on stack.
+    if (isDeallocatingStack())
+      return false;
+
+    // Check results and operands for packs.  If a pack appears, lowering the
+    // instruction might result in pack metadata emission.
+    for (auto result : getResults()) {
+      if (result->getType().hasAnyPack())
+        return true;
+    }
+    for (auto operandTy : getOperandTypes()) {
+      if (operandTy.hasAnyPack())
+        return true;
+    }
+    for (auto &tdo : getTypeDependentOperands()) {
+      if (tdo.get()->getType().hasAnyPack())
+        return true;
+    }
+
     return false;
   }
 }