[PATCH 1/8] Add new calling convention 'explicitcc'

[frej]

Summary

The 'explicitcc' calling convention is intended for functions which
are not full functions, instead they are code fragments where the
arguments are hardware registers. They are intended to be used to
generate code which can be inserted into to shadow of patchpoints and
stackmaps. The llvm.experimental.retwr intrinsic is typically used
to exit the function.

include/llvm/IR/CallingConv.h

     // (almost) all registers.
     PreserveAll = 15,
 
+    // Explicit - Calling convention for functions which are not full functions,
+    // instead they are code fragments where the arguments are hardware
+    // registers. They are intended to be used to generate code which can be
+    // inserted into to shadow of patchpoints and stackmaps.  The
+    // llvm.return_with_registers intrinsic is typically used to exit the
+    // function.
+    Explicit = 16,
+
     // Target - This is the start of the target-specific calling conventions,
     // e.g. fastcall and thiscall on X86.
     FirstTargetCC = 64,

lib/AsmParser/LLLexer.cpp

   KEYWORD(x86_64_win64cc);
   KEYWORD(webkit_jscc);
   KEYWORD(anyregcc);
+  KEYWORD(explicitcc);
   KEYWORD(preserve_mostcc);
   KEYWORD(preserve_allcc);
   KEYWORD(ghccc);

lib/AsmParser/LLParser.cpp

 ///   ::= 'x86_64_win64cc'
 ///   ::= 'webkit_jscc'
 ///   ::= 'anyregcc'
+///   ::= 'explicitcc'
 ///   ::= 'preserve_mostcc'
 ///   ::= 'preserve_allcc'
 ///   ::= 'ghccc'

   case lltok::kw_x86_64_win64cc: CC = CallingConv::X86_64_Win64; break;
   case lltok::kw_webkit_jscc:    CC = CallingConv::WebKit_JS; break;
   case lltok::kw_anyregcc:       CC = CallingConv::AnyReg; break;
+  case lltok::kw_explicitcc:     CC = CallingConv::Explicit; break;
   case lltok::kw_preserve_mostcc:CC = CallingConv::PreserveMost; break;
   case lltok::kw_preserve_allcc: CC = CallingConv::PreserveAll; break;
   case lltok::kw_ghccc:          CC = CallingConv::GHC; break;

lib/AsmParser/LLToken.h

     kw_ptx_kernel, kw_ptx_device,
     kw_spir_kernel, kw_spir_func,
     kw_x86_64_sysvcc, kw_x86_64_win64cc,
-    kw_webkit_jscc, kw_anyregcc,
+    kw_webkit_jscc, kw_anyregcc, kw_explicitcc,
     kw_preserve_mostcc, kw_preserve_allcc,
     kw_ghccc,
 

lib/IR/AsmWriter.cpp

   case CallingConv::Cold:          Out << "coldcc"; break;
   case CallingConv::WebKit_JS:     Out << "webkit_jscc"; break;
   case CallingConv::AnyReg:        Out << "anyregcc"; break;
+  case CallingConv::Explicit:      Out << "explicitcc"; break;
   case CallingConv::PreserveMost:  Out << "preserve_mostcc"; break;
   case CallingConv::PreserveAll:   Out << "preserve_allcc"; break;
   case CallingConv::GHC:           Out << "ghccc"; break;