Target/X86: Add explicit Win64 and System V/x86-64 calling conventions.

Summary:
This patch adds explicit calling convention types for the Win64 and
System V/x86-64 ABIs. This allows code to override the default, and use
the Win64 convention on a target that wants to use SysV (and
vice-versa). This is needed to implement the `ms_abi` and `sysv_abi` GNU
attributes.

Reviewers:

CC:

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186144 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 1 deletions

diff --git a/include/llvm/IR/CallingConv.h b/include/llvm/IR/CallingConv.h
index 6f3ab20..413f93a 100644
--- a/include/llvm/IR/CallingConv.h
+++ b/include/llvm/IR/CallingConv.h
@@ -119,8 +119,17 @@ namespace CallingConv {
     SPIR_KERNEL = 76,
 
     /// Intel_OCL_BI - Calling conventions for Intel OpenCL built-ins
-    Intel_OCL_BI = 77
+    Intel_OCL_BI = 77,
 
+    /// \brief The C convention as specified in the x86-64 supplement to the
+    /// System V ABI, used on most non-Windows systems.
+    X86_64_SysV = 78,
+
+    /// \brief The C convention as implemented on Windows/x86-64. This
+    /// convention differs from the more common \c X86_64_SysV convention
+    /// in a number of ways, most notably in that XMM registers used to pass
+    /// arguments are shadowed by GPRs, and vice versa.
+    X86_64_Win64 = 79
   };
 } // End CallingConv namespace