[opaque pointer types] Remove some calls to generic Type subtype accessors.

That is, remove many of the calls to Type::getNumContainedTypes(),
Type::subtypes(), and Type::getContainedType(N).

I'm not intending to remove these accessors -- they are
useful/necessary in some cases. However, removing the pointee type
from pointers would potentially break some uses, and reducing the
number of calls makes it easier to audit.

llvm-svn: 350835
diff --git a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
index cf2ce03..42d7ed5 100644
--- a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -347,7 +347,7 @@
   if (ArrayType *AT = dyn_cast<ArrayType>(Ty))
     return containsGCPtrType(AT->getElementType());
   if (StructType *ST = dyn_cast<StructType>(Ty))
-    return llvm::any_of(ST->subtypes(), containsGCPtrType);
+    return llvm::any_of(ST->elements(), containsGCPtrType);
   return false;
 }