Prevent JIT cache misses from nondeterministic typecast

We were casting a 2-bit bitfield to a char using a union, which
gave us a nondeterministic result.  This works fine since we
don't care about those other bits, but it causes cache misses.

src/codegen/compvars.cpp

@@ -675,17 +675,10 @@ CompilerVariable* UnknownType::callattr(IREmitter& emitter, const OpInfo& info,
     else
         func = g.funcs.callattrN;
 
-    union {
-        CallattrFlags flags;
-        char value;
-    } flags_to_int;
-    static_assert(sizeof(CallattrFlags) == sizeof(char), "");
-    flags_to_int.flags = flags;
-
     std::vector<llvm::Value*> other_args;
     other_args.push_back(var->getValue());
     other_args.push_back(embedRelocatablePtr(attr, g.llvm_str_type_ptr));
-    other_args.push_back(getConstantInt(flags_to_int.value, g.i8));
+    other_args.push_back(getConstantInt(flags.asInt(), g.i8));
 
     llvm::Value* llvm_argspec = llvm::ConstantInt::get(g.i32, argspec.asInt(), false);
     other_args.push_back(llvm_argspec);

src/codegen/entry.cpp

@@ -282,10 +282,12 @@ public:
             M->print(sstr, 0);
             sstr.flush();
 
+            llvm::sys::fs::create_directories(cache_dir.str());
             std::string filename = cache_dir.str().str() + "/" + module_identifier + "_first.ll";
             if (llvm::sys::fs::exists(filename))
                 filename = cache_dir.str().str() + "/" + module_identifier + "_second.ll";
             FILE* f = fopen(filename.c_str(), "wt");
+            ASSERT(f, "%s", strerror(errno));
             fwrite(llvm_ir.c_str(), 1, llvm_ir.size(), f);
             fclose(f);
 #endif

src/core/types.h

@@ -586,6 +586,8 @@ struct FrameInfo {
 struct CallattrFlags {
     bool cls_only : 1;
     bool null_on_nonexistent : 1;
+
+    char asInt() { return (cls_only << 0) + (null_on_nonexistent << 1); }
 };
 }