[llvm] r241794 - Add support for nest attribute to AArch64 backend

[Renato Golin]

Author: rengolin
Date: Thu Jul  9 05:18:02 2015
New Revision: 241794

URL: http://llvm.org/viewvc/llvm-project?rev=241794&view=rev
Log:
Add support for nest attribute to AArch64 backend

The nest attribute is currently supported on the x86 (32-bit) and x86-64
backends, but not on ARM (32-bit) or AArch64. This patch adds support for
nest to the AArch64 backend.

Register x18 is used by GCC for this purpose and hence is used here.
As discussed on the GCC mailing list the register choice is an ABI issue
and so choosing the same register as GCC means __builtin_call_with_static_chain
is compatible.

Patch by Stephen Cross.

Modified:
    llvm/trunk/lib/Target/AArch64/AArch64CallingConvention.td

Modified: llvm/trunk/lib/Target/AArch64/AArch64CallingConvention.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64CallingConvention.td?rev=241794&r1=241793&r2=241794&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64CallingConvention.td (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64CallingConvention.td Thu Jul  9 05:18:02 2015
@@ -40,6 +40,11 @@ def CC_AArch64_AAPCS : CallingConv<[
   // slot is 64-bit.
   CCIfByVal<CCPassByVal<8, 8>>,
 
+  // The 'nest' parameter, if any, is passed in X18.
+  // Darwin uses X18 as the platform register and hence 'nest' isn't currently
+  // supported there.
+  CCIfNest<CCAssignToReg<[X18]>>,
+
   CCIfConsecutiveRegs<CCCustom<"CC_AArch64_Custom_Block">>,
 
   // Handle i1, i8, i16, i32, i64, f32, f64 and v2f64 by passing in registers,