Add constant blinding/pooling option for X8632 code translation

src/IceGlobalContext.h

Index: src/IceGlobalContext.h
diff --git a/src/IceGlobalContext.h b/src/IceGlobalContext.h
index 763a75b487ced3554f3bf53127106f792eabdf31..a632253f801fb70e7eee71349b8a093f4be91d1f 100644
--- a/src/IceGlobalContext.h
+++ b/src/IceGlobalContext.h
@@ -72,7 +72,8 @@ class GlobalContext {
   X("Regs Saved  ", RegsSaved)                                                 \
   X("Frame Bytes ", FrameByte)                                                 \
   X("Spills      ", NumSpills)                                                 \
-  X("Fills       ", NumFills)
+  X("Fills       ", NumFills)                                                  \
+  X("R/P Imms    ", NumRPImms)
     //#define X(str, tag)
 
   public:
@@ -263,6 +264,15 @@ public:
     Tls->StatsCumulative.update(CodeStats::CS_NumFills);
   }
 
+  // Number of Randomized or Pooled Immediates
+  void statsUpdateRPImms() {
+    if (!getFlags().getDumpStats())
+      return;
+    ThreadContext *Tls = ICE_TLS_GET_FIELD(TLS);
+    Tls->StatsFunction.update(CodeStats::CS_NumRPImms);
+    Tls->StatsCumulative.update(CodeStats::CS_NumRPImms);
+  }
+
   // These are predefined TimerStackIdT values.
   enum TimerStackKind { TSK_Default = 0, TSK_Funcs, TSK_Num };
 
@@ -391,6 +401,21 @@ public:
     return Match.empty() || Match == SymbolName;
   }
 
+  // Return the randomization cookie for diversification.
+  // Initialize the cookie if necessary
+  uint32_t getRandomizationCookie() {
+    if (RandomizationCookie != 0)
+      return RandomizationCookie;
+    RandomizationCookieLock.lock();

[Jim Stichnoth, 2015/06/19 16:51:02]

You should use the std::unique_lock<> pattern (see other uses in Subzero) when
possible, rather than explicit lock()/unlock().

But to echo JF's point, you need to lock reads as well, which means moving the
lock(), or the unique_lock<>, to the beginning of the method.  But means tons of
extra lock operations, which you were clearly trying to avoid.

For now, I think you can just make RandomizationCookie a const field and pass it
into the ctor.  I.e., make the RNG.next() calls before GlobalContext is created.

In the future, we will probably want to hold this in the Cfg or TargetLowering
object.

+    while (RandomizationCookie == 0) {
+      RandomNumberGenerator &RNG = getRNG();
+      RandomizationCookie = (uint32_t)RNG.next(
+          (uint64_t)std::numeric_limits<uint32_t>::max() + 1);
+    }
+    RandomizationCookieLock.unlock();
+    return RandomizationCookie;
+  }
+
 private:
   // Try to ensure mutexes are allocated on separate cache lines.
 
@@ -460,6 +485,11 @@ private:
   typedef llvm::SmallVector<char, 32> ManglerVector;
   void incrementSubstitutions(ManglerVector &OldName) const;
 
+  // Randomization Cookie
+  // Managed by getRandomizationCookie()
+  GlobalLockType RandomizationCookieLock;
+  uint32_t RandomizationCookie;
+
 public:
   static void TlsInit() { ICE_TLS_INIT_FIELD(TLS); }
 };