Subzero: Add a random number generator.

src/IceGlobalContext.h

 //===- subzero/src/IceGlobalContext.h - Global context defs -----*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares aspects of the compilation that persist across
 // multiple functions.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef SUBZERO_SRC_ICEGLOBALCONTEXT_H
 #define SUBZERO_SRC_ICEGLOBALCONTEXT_H
 
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/raw_ostream.h"
 
 #include "IceDefs.h"
 #include "IceIntrinsics.h"
 #include "IceTypes.h"
+#include "IceRNG.h"

[Jim Stichnoth, 2014/08/08 05:05:38]

alphabetize includes

[wala, 2014/08/08 16:36:13]

Done.

 
 namespace Ice {
 
 // TODO: Accesses to all non-const fields of GlobalContext need to
 // be synchronized, especially the constant pool, the allocator, and
 // the output streams.
 class GlobalContext {
 public:
   GlobalContext(llvm::raw_ostream *OsDump, llvm::raw_ostream *OsEmit,
                 VerboseMask Mask, TargetArch Arch, OptLevel Opt,
@@ skipping 49 matching lines @@
   Constant *getConstantZero(Type Ty);
   // getConstantPool() returns a copy of the constant pool for
   // constants of a given type.
   ConstantList getConstantPool(Type Ty) const;
 
   // Allocate data of type T using the global allocator.
   template <typename T> T *allocate() { return Allocator.Allocate<T>(); }
 
   const Intrinsics &getIntrinsicsInfo() const { return IntrinsicsInfo; }
 
+  RandomNumberGenerator &getRNG() { return RNG; }

[Jim Stichnoth, 2014/08/08 05:05:38]

Please add TODOs in appropriate places:

1. Switch to RNG implementation from LLVM or C++11.

2. Make the RNG play nicely with multithreaded translation.

3. Make it possible to replay the RNG sequence in a subsequent run, for
reproducing a bug.  Print the seed/whatever in a comment in the asm output. 
Embed the seed in the binary via metadata that an attacker can't introspect.

[wala, 2014/08/08 16:36:13]

Done.

+
 private:
   Ostream *StrDump; // Stream for dumping / diagnostics
   Ostream *StrEmit; // Stream for code emission
 
   llvm::BumpPtrAllocator Allocator;
   VerboseMask VMask;
   llvm::OwningPtr<class ConstantPool> ConstPool;
   Intrinsics IntrinsicsInfo;
   const TargetArch Arch;
   const OptLevel Opt;
   const IceString TestPrefix;
   bool HasEmittedFirstMethod;
+  RandomNumberGenerator RNG;
   GlobalContext(const GlobalContext &) LLVM_DELETED_FUNCTION;
   GlobalContext &operator=(const GlobalContext &) LLVM_DELETED_FUNCTION;
 
   // Private helpers for mangleName()
   typedef llvm::SmallVector<char, 32> ManglerVector;
   void incrementSubstitutions(ManglerVector &OldName) const;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEGLOBALCONTEXT_H