RequirementMachine: Add -requirement-machine-protocol-signatures= flag

There are three settings, on, off and verify. Not hooked up quite yet.

Author: slavapestov

include/swift/Basic/LangOptions.h

@@ -481,6 +481,11 @@ namespace swift {
     /// algorithm.
     unsigned RequirementMachineDepthLimit = 10;
 
+    /// Enable the new experimental protocol requirement signature minimization
+    /// algorithm.
+    RequirementMachineMode RequirementMachineProtocolSignatures =
+        RequirementMachineMode::Disabled;
+
     /// Sets the target we are building for and updates platform conditions
     /// to match.
     ///

include/swift/Option/Options.td

@@ -616,6 +616,10 @@ def requirement_machine_EQ : Joined<["-"], "requirement-machine=">,
   Flags<[FrontendOption, ModuleInterfaceOption]>,
   HelpText<"Control usage of experimental generics implementation: 'on', 'off', or 'verify'">;
 
+def requirement_machine_protocol_signatures_EQ : Joined<["-"], "requirement-machine-protocol-signatures=">,
+  Flags<[FrontendOption]>,
+  HelpText<"Control usage of experimental protocol requirement signature minimization: 'on', 'off', or 'verify'">;
+
 // Diagnostic control options
 def suppress_warnings : Flag<["-"], "suppress-warnings">,
   Flags<[FrontendOption]>,

lib/Frontend/CompilerInvocation.cpp

@@ -831,13 +831,12 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
     }
   }
 
-  if (auto A =
-          Args.getLastArg(OPT_requirement_machine_EQ)) {
+  if (auto A = Args.getLastArg(OPT_requirement_machine_EQ)) {
     auto value = llvm::StringSwitch<Optional<RequirementMachineMode>>(A->getValue())
-      .Case("off", RequirementMachineMode::Disabled)
-      .Case("on", RequirementMachineMode::Enabled)
-      .Case("verify", RequirementMachineMode::Verify)
-      .Default(None);
+        .Case("off", RequirementMachineMode::Disabled)
+        .Case("on", RequirementMachineMode::Enabled)
+        .Case("verify", RequirementMachineMode::Verify)
+        .Default(None);
 
     if (value)
       Opts.EnableRequirementMachine = *value;
@@ -846,6 +845,20 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
                      A->getAsString(Args), A->getValue());
   }
 
+  if (auto A = Args.getLastArg(OPT_requirement_machine_protocol_signatures_EQ)) {
+    auto value = llvm::StringSwitch<Optional<RequirementMachineMode>>(A->getValue())
+        .Case("off", RequirementMachineMode::Disabled)
+        .Case("on", RequirementMachineMode::Enabled)
+        .Case("verify", RequirementMachineMode::Verify)
+        .Default(None);
+
+    if (value)
+      Opts.RequirementMachineProtocolSignatures = *value;
+    else
+      Diags.diagnose(SourceLoc(), diag::error_invalid_arg_value,
+                     A->getAsString(Args), A->getValue());
+  }
+
   Opts.DumpRequirementMachine = Args.hasArg(
       OPT_dump_requirement_machine);
   Opts.AnalyzeRequirementMachine = Args.hasArg(