[llvm-exegesis][NFC] Add missing header guard + cosmetics.

Reviewers: gchatelet

Reviewed By: gchatelet

Subscribers: tschuett, llvm-commits

Differential Revision: https://reviews.llvm.org/D54252

llvm-svn: 346400
diff --git a/llvm/tools/llvm-exegesis/lib/RegisterValue.h b/llvm/tools/llvm-exegesis/lib/RegisterValue.h
index 51ea30a..689e354 100644
--- a/llvm/tools/llvm-exegesis/lib/RegisterValue.h
+++ b/llvm/tools/llvm-exegesis/lib/RegisterValue.h
@@ -14,6 +14,9 @@
 ///
 //===----------------------------------------------------------------------===//
 
+#ifndef LLVM_TOOLS_LLVM_EXEGESIS_REGISTERVALUE_H
+#define LLVM_TOOLS_LLVM_EXEGESIS_REGISTERVALUE_H
+
 #include <llvm/ADT/APFloat.h>
 #include <llvm/ADT/APInt.h>
 
@@ -22,6 +25,7 @@
 
 // A simple object storing the value for a particular register.
 struct RegisterValue {
+  static RegisterValue zero(unsigned Reg) { return {Reg, llvm::APInt()}; }
   unsigned Register;
   llvm::APInt Value;
 };
@@ -45,3 +49,5 @@
 
 } // namespace exegesis
 } // namespace llvm
+
+#endif // LLVM_TOOLS_LLVM_EXEGESIS_REGISTERVALUE_H
diff --git a/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp b/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp
index eb6a857..88ba315 100644
--- a/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp
+++ b/llvm/tools/llvm-exegesis/lib/SnippetGenerator.cpp
@@ -91,7 +91,7 @@
       if (Op.isUse()) {
         const unsigned Reg = GetOpReg(Op);
         if (Reg > 0 && !DefinedRegs.test(Reg)) {
-          RIV.push_back(RegisterValue{Reg, llvm::APInt()});
+          RIV.push_back(RegisterValue::zero(Reg));
           DefinedRegs.set(Reg);
         }
       }