AMDGPU: Set calling_convention bit in kernel_code_t

[arsenm]

Summary

According to the documentation this is supposed to be -1
if indirect calls are not supported.

[kzhuravl]

LGTM.

[arsenm]

r293081

lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp

void initDefaultAMDKernelCodeT(amd_kernel_code_t &Header,
   Header.amd_kernel_code_version_minor = 0;
   Header.amd_machine_kind = 1; // AMD_MACHINE_KIND_AMDGPU
   Header.amd_machine_version_major = ISA.Major;
   Header.amd_machine_version_minor = ISA.Minor;
   Header.amd_machine_version_stepping = ISA.Stepping;
   Header.kernel_code_entry_byte_offset = sizeof(Header);
   // wavefront_size is specified as a power of 2: 2^6 = 64 threads.
   Header.wavefront_size = 6;
+
+  // If the code object does not support indirect functions, then the value must
+  // be 0xffffffff.
+  Header.call_convention = -1;
+
   // These alignment values are specified in powers of two, so alignment =
   // 2^n.  The minimum alignment is 2^4 = 16.
   Header.kernarg_segment_alignment = 4;
   Header.group_segment_alignment = 4;
   Header.private_segment_alignment = 4;
 }
 
 MCSection *getHSATextSection(MCContext &Ctx) {

test/CodeGen/AMDGPU/hsa.ll

 ; HSA-CI: .hsa_code_object_isa 7,0,0,"AMD","AMDGPU"
 ; HSA-VI: .hsa_code_object_isa 8,0,1,"AMD","AMDGPU"
 
 ; HSA: .amdgpu_hsa_kernel simple
 ; HSA: {{^}}simple:
 ; HSA: .amd_kernel_code_t
 ; HSA: enable_sgpr_private_segment_buffer = 1
 ; HSA: enable_sgpr_kernarg_segment_ptr = 1
+; HSA: wavefront_size = 6
+; HSA: call_convention = -1
 ; HSA: .end_amd_kernel_code_t
 ; HSA: s_load_dwordx2 s[{{[0-9]+:[0-9]+}}], s[4:5], 0x0
 
 ; Make sure we are setting the ATC bit:
 ; HSA-CI: s_mov_b32 s[[HI:[0-9]]], 0x100f000
 ; On VI+ we also need to set MTYPE = 2
 ; HSA-VI: s_mov_b32 s[[HI:[0-9]]], 0x1100f000
 ; Make sure we generate flat store for HSA