+//===----------------------------------------------------------------------===//
+// ARM64 Calling Convention for GHC
+//===----------------------------------------------------------------------===//
+
+// This calling convention is specific to the Glasgow Haskell Compiler.
+// The only documentation is the GHC source code, specifically the C header
+// file:
+//
+// https://github.com/ghc/ghc/blob/master/includes/stg/MachRegs.h
+//
+// which defines the registers for the Spineless Tagless G-Machine (STG) that
+// GHC uses to implement lazy evaluation. The generic STG machine has a set of
+// registers which are mapped to appropriate set of architecture specific
+// registers for each CPU architecture.
+//
+// The STG Machine is documented here:
+//
+// https://ghc.haskell.org/trac/ghc/wiki/Commentary/Compiler/GeneratedCode
+//
+// The AArch64 register mapping is under the heading "The ARMv8/AArch64 ABI
+// register mapping".
+
+def CC_AArch64_GHC : CallingConv<[
+ // Handle all vector types as either f64 or v2f64.
+ CCIfType<[v1i64, v2i32, v4i16, v8i8, v2f32], CCBitConvertToType<f64>>,
+ CCIfType<[v2i64, v4i32, v8i16, v16i8, v4f32, f128], CCBitConvertToType<v2f64>>,
+
+ CCIfType<[v2f64], CCAssignToReg<[Q4, Q5]>>,
+ CCIfType<[f32], CCAssignToReg<[S8, S9, S10, S11]>>,
+ CCIfType<[f64], CCAssignToReg<[D12, D13, D14, D15]>>,
+
+ // Promote i8/i16/i32 arguments to i64.
+ CCIfType<[i8, i16, i32], CCPromoteToType<i64>>,
+
+ // Pass in STG registers: Base, Sp, Hp, R1, R2, R3, R4, R5, R6, SpLim
+ CCIfType<[i64], CCAssignToReg<[X19, X20, X21, X22, X23, X24, X25, X26, X27, X28]>>
+]>;
+