Performance annotations: add attributes @_noLocks and @_noAllocation

include/swift/SIL/SILFunction.h

@@ -60,6 +60,12 @@ enum IsExactSelfClass_t {
   IsExactSelfClass,
 };
 
+enum class PerformanceConstraints : uint8_t {
+  None = 0,
+  NoAllocation = 1,
+  NoLocks = 2,
+};
+
 class SILSpecializeAttr final {
   friend SILFunction;
 public:
@@ -232,6 +238,8 @@ private:
 
   Purpose specialPurpose = Purpose::None;
 
+  PerformanceConstraints perfConstraints = PerformanceConstraints::None;
+
   /// This is the number of uses of this SILFunction inside the SIL.
   /// It does not include references from debug scopes.
   unsigned RefCount = 0;
@@ -813,6 +821,12 @@ public:
     OptMode = unsigned(mode);
   }
 
+  PerformanceConstraints getPerfConstraints() const { return perfConstraints; }
+
+  void setPerfConstraints(PerformanceConstraints perfConstr) {
+    perfConstraints = perfConstr;
+  }
+
   /// \returns True if the function is optimizable (i.e. not marked as no-opt),
   ///          or is raw SIL (so that the mandatory passes still run).
   bool shouldOptimize() const;