Don't leave the FPOptions in a UnaryOperator uninitialized.

We don't appear to use these FPOptions for anything right now, but
they shouldn't be uninitialized because that makes our AST file output
nondeterministic.

clang/lib/AST/Expr.cpp

@@ -4569,6 +4569,8 @@ UnaryOperator::UnaryOperator(const ASTContext &Ctx, Expr *input, Opcode opc,
   UnaryOperatorBits.CanOverflow = CanOverflow;
   UnaryOperatorBits.Loc = l;
   UnaryOperatorBits.HasFPFeatures = FPFeatures.requiresTrailingStorage();
+  if (hasStoredFPFeatures())
+    setStoredFPFeatures(FPFeatures);
   setDependence(computeDependence(this));
 }
 

clang/test/PCH/determinism.cpp

@@ -0,0 +1,18 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+
+// RUN: %clang_cc1 -x c++-header %s -emit-pch -o %t/a.pch
+// RUN: %clang_cc1 -x c++-header %s -emit-pch -o %t/b.pch
+// RUN: cmp %t/a.pch %t/b.pch
+
+#pragma float_control(push)
+double fp_control_1(double x) {
+#pragma float_control(precise, on)
+  return -x + x;
+}
+
+double fp_control_2(double x) {
+#pragma float_control(precise, off)
+  return -x + x;
+}
+#pragma float_control(pop)