For << and >> with C++, detect when all instances are shifting by the same amount.

In this case, we now emit calls to potentially-specialized functions for the
left/right shifts that take a single integer value for the shift amount.  These
in turn can be matched to the corresponding intrinsics for the SSE target.

Issue #145.

llvmutil.h

@@ -38,12 +38,23 @@
 #ifndef ISPC_LLVMUTIL_H
 #define ISPC_LLVMUTIL_H 1
 
-#include "ispc.h"
 #include <llvm/LLVMContext.h>
 #include <llvm/Type.h>
 #include <llvm/DerivedTypes.h>
 #include <llvm/Constants.h>
 
+namespace llvm {
+    class PHINode;
+    class InsertElementInst;
+}
+
+// llvm::Type *s are no longer const in llvm 3.0
+#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
+#define LLVM_TYPE_CONST
+#else
+#define LLVM_TYPE_CONST const
+#endif
+
 
 /** This structure holds pointers to a variety of LLVM types; code
     elsewhere can use them from here, ratherthan needing to make more
@@ -99,6 +110,7 @@ extern llvm::Constant *LLVMTrue, *LLVMFalse;
     of LLVMTypes and the LLVMTrue/LLVMFalse constants.  However, it can't
     be called until the compilation target is known.
  */
+struct Target;
 extern void InitLLVMUtil(llvm::LLVMContext *ctx, Target target);
 
 /** Returns an LLVM i8 constant of the given value */
@@ -205,4 +217,13 @@ extern llvm::Constant *LLVMMaskAllOn;
 /** LLVM constant value representing an 'all off' SIMD lane mask */
 extern llvm::Constant *LLVMMaskAllOff;
 
+/** Tests to see if all of the elements of the vector in the 'v' parameter
+    are equal.  Like lValuesAreEqual(), this is a conservative test and may
+    return false for arrays where the values are actually all equal.  */
+extern bool LLVMVectorValuesAllEqual(llvm::Value *v, int vectorLength,
+                                     std::vector<llvm::PHINode *> &seenPhis);
+
+void LLVMFlattenInsertChain(llvm::InsertElementInst *ie, int vectorWidth,
+                            llvm::Value **elements);
+
 #endif // ISPC_LLVMUTIL_H