[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/SIL/IR/SILInstruction.cpp

@@ -1318,6 +1318,18 @@ bool SILInstruction::mayRequirePackMetadata() const {
     return ty->hasPack();
   }
   default:
+    for (auto result : getResults()) {
+      if (result->getType().hasPack())
+        return true;
+    }
+    for (auto operandTy : getOperandTypes()) {
+      if (operandTy.hasPack())
+        return true;
+    }
+    for (auto &tdo : getTypeDependentOperands()) {
+      if (tdo.get()->getType().hasPack())
+        return true;
+    }
     return false;
   }
 }