RequirementMachine: Add -analyze-requirement-machine flag to print statistics

Author: slavapestov

include/swift/Basic/LangOptions.h

@@ -464,6 +464,9 @@ namespace swift {
     /// Enables debugging output from the requirement machine.
     bool DebugRequirementMachine = false;
 
+    /// Enables statistics output from the requirement machine.
+    bool AnalyzeRequirementMachine = false;
+
     /// Maximum iteration count for requirement machine confluent completion
     /// algorithm.
     unsigned RequirementMachineStepLimit = 2000;

include/swift/Option/FrontendOptions.td

@@ -276,6 +276,10 @@ def disable_named_lazy_member_loading : Flag<["-"], "disable-named-lazy-member-l
 def debug_requirement_machine : Flag<["-"], "debug-requirement-machine">,
   HelpText<"Enables debugging output from the generics implementation">;
 
+def analyze_requirement_machine : Flag<["-"], "analyze-requirement-machine">,
+  Flags<[FrontendOption, HelpHidden, DoesNotAffectIncrementalBuild]>,
+  HelpText<"Print out requirement machine statistics at the end of the compilation job">;
+
 def requirement_machine_step_limit : Separate<["-"], "requirement-machine-step-limit">,
   Flags<[FrontendOption, HelpHidden, DoesNotAffectIncrementalBuild]>,
   HelpText<"Set the maximum steps before we give up on confluent completion">;

lib/Frontend/CompilerInvocation.cpp

@@ -829,6 +829,8 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
 
   Opts.DebugRequirementMachine = Args.hasArg(
       OPT_debug_requirement_machine);
+  Opts.AnalyzeRequirementMachine = Args.hasArg(
+      OPT_analyze_requirement_machine);
 
   if (const Arg *A = Args.getLastArg(OPT_requirement_machine_step_limit)) {
     unsigned limit;