Address rewview feedback

- Renames ExperimentalPlatformCCallingConvention to
  PlatformCCallingConvention.
- Removes non-arm calling convention support as this feature is working
  around a clang bug for some arm triples which we hope to see resolved.
- Removes misleading MetaVarName from platform-c-calling-convention
  argument.
- Replaces other uses of LLVM::CallingConv::C with
  IGM.getOptions().PlatformCCallingConvention().

Author: rauhul

include/swift/AST/IRGenOptions.h

@@ -479,7 +479,7 @@ class IRGenOptions {
   std::string TrapFuncName = "";
 
   /// The calling convention used to perform non-swift calls.
-  llvm::CallingConv::ID ExperimentalPlatformCCallingConvention;
+  llvm::CallingConv::ID PlatformCCallingConvention;
 
   IRGenOptions()
       : DWARFVersion(2),
@@ -522,7 +522,7 @@ class IRGenOptions {
         UseRelativeProtocolWitnessTables(false), CmdArgs(),
         SanitizeCoverage(llvm::SanitizerCoverageOptions()),
         TypeInfoFilter(TypeInfoDumpFilter::All),
-        ExperimentalPlatformCCallingConvention(llvm::CallingConv::C) {
+        PlatformCCallingConvention(llvm::CallingConv::C) {
 #ifndef NDEBUG
     DisableRoundTripDebugTypes = false;
 #else

include/swift/Option/FrontendOptions.td

@@ -1225,12 +1225,11 @@ def enable_ossa_complete_lifetimes :
   Flag<["-"], "enable-ossa-complete-lifetimes">,
   HelpText<"Require linear OSSA lifetimes after SILGen">;
 
-def experimental_platform_c_calling_convention :
+def platform_c_calling_convention :
     Separate<["-"], "experimental-platform-c-calling-convention">,
     HelpText<"Which calling convention is used to perform non-swift calls. "
-             "Defaults to llvm's standard C calling convention.">,
-    MetaVarName<"standard|task-to-thread">;
-def experimental_platform_c_calling_convention_EQ :
+             "Defaults to llvm's standard C calling convention.">;
+def platform_c_calling_convention_EQ :
     Joined<["-"], "experimental-platform-c-calling-convention=">,
-    Alias<experimental_platform_c_calling_convention>;
+    Alias<platform_c_calling_convention>;
 } // end let Flags = [FrontendOption, NoDriverOption, HelpHidden]

lib/Frontend/CompilerInvocation.cpp

@@ -2807,62 +2807,13 @@ static bool ParseIRGenArgs(IRGenOptions &Opts, ArgList &Args,
     return true;
   }
 
-  if (const Arg *A = Args.getLastArg(options::OPT_experimental_platform_c_calling_convention)) {
-    Opts.ExperimentalPlatformCCallingConvention =
+  if (const Arg *A = Args.getLastArg(options::OPT_platform_c_calling_convention)) {
+    Opts.PlatformCCallingConvention =
       llvm::StringSwitch<llvm::CallingConv::ID>(A->getValue())
         .Case("c", llvm::CallingConv::C)
-        .Case("fast", llvm::CallingConv::Fast)
-        .Case("cold", llvm::CallingConv::Cold)
-        .Case("ghc", llvm::CallingConv::GHC)
-        .Case("hipe", llvm::CallingConv::HiPE)
-        .Case("webkit_js", llvm::CallingConv::WebKit_JS)
-        .Case("anyreg", llvm::CallingConv::AnyReg)
-        .Case("preservemost", llvm::CallingConv::PreserveMost)
-        .Case("preserveall", llvm::CallingConv::PreserveAll)
-        .Case("swift", llvm::CallingConv::Swift)
-        .Case("cxx_fast_tls", llvm::CallingConv::CXX_FAST_TLS)
-        .Case("tail", llvm::CallingConv::Tail)
-        .Case("cfguard_check", llvm::CallingConv::CFGuard_Check)
-        .Case("swifttail", llvm::CallingConv::SwiftTail)
-        .Case("firsttargetcc", llvm::CallingConv::FirstTargetCC)
-        .Case("x86_stdcall", llvm::CallingConv::X86_StdCall)
-        .Case("x86_fastcall", llvm::CallingConv::X86_FastCall)
         .Case("arm_apcs", llvm::CallingConv::ARM_APCS)
         .Case("arm_aapcs", llvm::CallingConv::ARM_AAPCS)
         .Case("arm_aapcs_vfp", llvm::CallingConv::ARM_AAPCS_VFP)
-        .Case("msp430_intr", llvm::CallingConv::MSP430_INTR)
-        .Case("x86_thiscall", llvm::CallingConv::X86_ThisCall)
-        .Case("ptx_kernel", llvm::CallingConv::PTX_Kernel)
-        .Case("ptx_device", llvm::CallingConv::PTX_Device)
-        .Case("spir_func", llvm::CallingConv::SPIR_FUNC)
-        .Case("spir_kernel", llvm::CallingConv::SPIR_KERNEL)
-        .Case("intel_ocl_bi", llvm::CallingConv::Intel_OCL_BI)
-        .Case("x86_64_sysv", llvm::CallingConv::X86_64_SysV)
-        .Case("win64", llvm::CallingConv::Win64)
-        .Case("x86_vectorcall", llvm::CallingConv::X86_VectorCall)
-        .Case("x86_intr", llvm::CallingConv::X86_INTR)
-        .Case("avr_intr", llvm::CallingConv::AVR_INTR)
-        .Case("avr_signal", llvm::CallingConv::AVR_SIGNAL)
-        .Case("avr_builtin", llvm::CallingConv::AVR_BUILTIN)
-        .Case("amdgpu_vs", llvm::CallingConv::AMDGPU_VS)
-        .Case("amdgpu_gs", llvm::CallingConv::AMDGPU_GS)
-        .Case("amdgpu_ps", llvm::CallingConv::AMDGPU_PS)
-        .Case("amdgpu_cs", llvm::CallingConv::AMDGPU_CS)
-        .Case("amdgpu_kernel", llvm::CallingConv::AMDGPU_KERNEL)
-        .Case("x86_regcall", llvm::CallingConv::X86_RegCall)
-        .Case("amdgpu_hs", llvm::CallingConv::AMDGPU_HS)
-        .Case("msp430_builtin", llvm::CallingConv::MSP430_BUILTIN)
-        .Case("amdgpu_ls", llvm::CallingConv::AMDGPU_LS)
-        .Case("amdgpu_es", llvm::CallingConv::AMDGPU_ES)
-        .Case("aarch64_vectorcall", llvm::CallingConv::AArch64_VectorCall)
-        .Case("aarch64_sve_vectorcall", llvm::CallingConv::AArch64_SVE_VectorCall)
-        .Case("wasm_emscripteninvoke", llvm::CallingConv::WASM_EmscriptenInvoke)
-        .Case("amdgpu_gfx", llvm::CallingConv::AMDGPU_Gfx)
-        .Case("m68k_intr", llvm::CallingConv::M68k_INTR)
-        .Case("aarch64_sme_abi_support_routines_preservemost_from_x0",
-              llvm::CallingConv::AArch64_SME_ABI_Support_Routines_PreserveMost_From_X0)
-        .Case("aarch64_sme_abi_support_routines_preservemost_from_x2",
-              llvm::CallingConv::AArch64_SME_ABI_Support_Routines_PreserveMost_From_X2)
         .Default(llvm::CallingConv::C);
   }
 

lib/IRGen/GenCall.cpp

@@ -322,7 +322,7 @@ llvm::CallingConv::ID irgen::expandCallingConv(IRGenModule &IGM,
   case SILFunctionTypeRepresentation::ObjCMethod:
   case SILFunctionTypeRepresentation::CXXMethod:
   case SILFunctionTypeRepresentation::Block:
-    return IGM.getOptions().ExperimentalPlatformCCallingConvention;
+    return IGM.getOptions().PlatformCCallingConvention;
 
   case SILFunctionTypeRepresentation::Method:
   case SILFunctionTypeRepresentation::WitnessMethod:

lib/IRGen/GenDecl.cpp

@@ -3297,7 +3297,7 @@ llvm::Constant *swift::irgen::emitCXXConstructorThunkIfNeeded(
   llvm::Function *thunk = llvm::Function::Create(
       assumedFnType, llvm::Function::PrivateLinkage, name, &IGM.Module);
 
-  thunk->setCallingConv(llvm::CallingConv::C);
+  thunk->setCallingConv(IGM.getOptions().PlatformCCallingConvention());
 
   llvm::AttrBuilder attrBuilder(IGM.getLLVMContext());
   IGM.constructInitialFnAttributes(attrBuilder);

lib/IRGen/GenHeap.cpp

@@ -1978,7 +1978,7 @@ emitHeapMetadataRefForUnknownHeapObject(IRGenFunction &IGF,
   auto metadata = IGF.Builder.CreateCall(
       IGF.IGM.getGetObjectClassFunctionPointer(), object);
   metadata->setName(object->getName() + ".Type");
-  metadata->setCallingConv(llvm::CallingConv::C);
+  metadata->setCallingConv(IGM.getOptions().PlatformCCallingConvention());
   metadata->setDoesNotThrow();
   metadata->addFnAttr(llvm::Attribute::ReadOnly);
   return metadata;

lib/IRGen/IRGenModule.cpp

@@ -570,7 +570,7 @@ IRGenModule::IRGenModule(IRGenerator &irgen,
   InvariantNode = llvm::MDNode::get(getLLVMContext(), {});
   DereferenceableID = getLLVMContext().getMDKindID("dereferenceable");
 
-  C_CC = llvm::CallingConv::C;
+  C_CC = IGM.getOptions().PlatformCCallingConvention();
   // TODO: use "tinycc" on platforms that support it
   DefaultCC = SWIFT_DEFAULT_LLVM_CC;
   SwiftCC = llvm::CallingConv::Swift;