Update Clang to emit the new form of llvm.cttz and llvm.ctlz intrinsics,
setting the is_zero_undef flag appropriately to true as that matches the
semantics of these GCC builtins.

This is the Clang side of r146357 in LLVM.

llvm-svn: 146358
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 419dddd..ce86cc4 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -237,7 +237,7 @@
     Value *F = CGM.getIntrinsic(Intrinsic::cttz, ArgType);
 
     llvm::Type *ResultType = ConvertType(E->getType());
-    Value *Result = Builder.CreateCall(F, ArgValue);
+    Value *Result = Builder.CreateCall2(F, ArgValue, Builder.getTrue());
     if (Result->getType() != ResultType)
       Result = Builder.CreateIntCast(Result, ResultType, /*isSigned*/true,
                                      "cast");
@@ -252,7 +252,7 @@
     Value *F = CGM.getIntrinsic(Intrinsic::ctlz, ArgType);
 
     llvm::Type *ResultType = ConvertType(E->getType());
-    Value *Result = Builder.CreateCall(F, ArgValue);
+    Value *Result = Builder.CreateCall2(F, ArgValue, Builder.getTrue());
     if (Result->getType() != ResultType)
       Result = Builder.CreateIntCast(Result, ResultType, /*isSigned*/true,
                                      "cast");
@@ -268,7 +268,8 @@
     Value *F = CGM.getIntrinsic(Intrinsic::cttz, ArgType);
 
     llvm::Type *ResultType = ConvertType(E->getType());
-    Value *Tmp = Builder.CreateAdd(Builder.CreateCall(F, ArgValue),
+    Value *Tmp = Builder.CreateAdd(Builder.CreateCall2(F, ArgValue,
+                                                       Builder.getTrue()),
                                    llvm::ConstantInt::get(ArgType, 1));
     Value *Zero = llvm::Constant::getNullValue(ArgType);
     Value *IsZero = Builder.CreateICmpEQ(ArgValue, Zero, "iszero");