[clang][wip] Implement conditional freeze_bit metadata emission

This work-in-progress commit enhances Clang to conditionally emit freeze_bit
metadata for load instructions. The emission is based on the nondeterministic
initialization status of the Address class.

Author: jmciver

clang/lib/CodeGen/CGBuilder.h

@@ -106,22 +106,23 @@ class CGBuilderTy : public CGBuilderBaseTy {
   // Note that we intentionally hide the CreateLoad APIs that don't
   // take an alignment.
   llvm::LoadInst *CreateLoad(Address Addr, const llvm::Twine &Name = "") {
-    return CreateAlignedLoad(Addr.getElementType(),
-                             emitRawPointerFromAddress(Addr),
-                             Addr.getAlignment().getAsAlign(), Name);
+    return CreateAlignedLoad(
+        Addr.getElementType(), emitRawPointerFromAddress(Addr),
+        Addr.getAlignment().getAsAlign(), Name, !Addr.isNondeterministicInit());
   }
   llvm::LoadInst *CreateLoad(Address Addr, const char *Name) {
     // This overload is required to prevent string literals from
     // ending up in the IsVolatile overload.
-    return CreateAlignedLoad(Addr.getElementType(),
-                             emitRawPointerFromAddress(Addr),
-                             Addr.getAlignment().getAsAlign(), Name);
+    return CreateAlignedLoad(
+        Addr.getElementType(), emitRawPointerFromAddress(Addr),
+        Addr.getAlignment().getAsAlign(), Name, !Addr.isNondeterministicInit());
   }
   llvm::LoadInst *CreateLoad(Address Addr, bool IsVolatile,
                              const llvm::Twine &Name = "") {
-    return CreateAlignedLoad(
-        Addr.getElementType(), emitRawPointerFromAddress(Addr),
-        Addr.getAlignment().getAsAlign(), IsVolatile, Name);
+    return CreateAlignedLoad(Addr.getElementType(),
+                             emitRawPointerFromAddress(Addr),
+                             Addr.getAlignment().getAsAlign(), IsVolatile, Name,
+                             !Addr.isNondeterministicInit());
   }
 
   using CGBuilderBaseTy::CreateAlignedLoad;