[SR-14453] Removed unused option enable_swiftcall.

Author: jirid

include/swift/AST/IRGenOptions.h

@@ -323,9 +323,6 @@ class IRGenOptions {
   /// measurements on a non-clean build directory.
   unsigned UseIncrementalLLVMCodeGen : 1;
 
-  /// Enable use of the swiftcall calling convention.
-  unsigned UseSwiftCall : 1;
-
   /// Enable the use of type layouts for value witness functions and use
   /// vw functions instead of outlined copy/destroy functions.
   unsigned UseTypeLayoutValueHandling : 1;
@@ -396,7 +393,7 @@ class IRGenOptions {
         ForcePublicLinkage(false), LazyInitializeClassMetadata(false),
         LazyInitializeProtocolConformances(false), DisableLegacyTypeInfo(false),
         PrespecializeGenericMetadata(false), UseIncrementalLLVMCodeGen(true),
-        UseSwiftCall(false), UseTypeLayoutValueHandling(true),
+        UseTypeLayoutValueHandling(true),
         GenerateProfile(false), EnableDynamicReplacementChaining(false),
         DisableRoundTripDebugTypes(false), DisableDebuggerShadowCopies(false),
         DisableConcreteTypeMetadataMangledNameAccessors(false), CmdArgs(),

include/swift/Option/FrontendOptions.td

@@ -126,9 +126,6 @@ def diagnostic_documentation_path
   : Separate<["-"], "diagnostic-documentation-path">, MetaVarName<"<path>">,
   HelpText<"Path to diagnostic documentation resources">;
 
-def enable_swiftcall : Flag<["-"], "enable-swiftcall">,
-  HelpText<"Enable the use of LLVM swiftcall support">;
-
 def enable_testable_attr_requires_testable_module :
   Flag<["-"], "enable-testable-attr-requires-testable-module">,
   HelpText<"Enable checking of @testable">;

lib/Frontend/CompilerInvocation.cpp

@@ -1568,8 +1568,6 @@ static bool ParseIRGenArgs(IRGenOptions &Opts, ArgList &Args,
     Opts.UseTypeLayoutValueHandling = false;
   }
 
-  Opts.UseSwiftCall = Args.hasArg(OPT_enable_swiftcall);
-
   // This is set to true by default.
   Opts.UseIncrementalLLVMCodeGen &=
     !Args.hasArg(OPT_disable_incremental_llvm_codegeneration);