[NVPTX] Support .maxnreg annotation.

llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXBaseInfo.h

 enum PropertyAnnotation {
   PROPERTY_MAXNTID_X = 0,
   PROPERTY_MAXNTID_Y,
   PROPERTY_MAXNTID_Z,
   PROPERTY_REQNTID_X,
   PROPERTY_REQNTID_Y,
   PROPERTY_REQNTID_Z,
   PROPERTY_MINNCTAPERSM,
+  PROPERTY_MAXNREG,
   PROPERTY_ISTEXTURE,
   PROPERTY_ISSURFACE,
   PROPERTY_ISSAMPLER,
   PROPERTY_ISREADONLY_IMAGE_PARAM,
   PROPERTY_ISWRITEONLY_IMAGE_PARAM,
   PROPERTY_ISREADWRITE_IMAGE_PARAM,
   PROPERTY_ISKERNEL_FUNCTION,
   PROPERTY_ALIGN,

llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXBaseInfo.cpp

const char *PropertyAnnotationName(PropertyAnnotation A) {
   case PROPERTY_REQNTID_X:
     return "reqntidx";
   case PROPERTY_REQNTID_Y:
     return "reqntidy";
   case PROPERTY_REQNTID_Z:
     return "reqntidz";
   case PROPERTY_MINNCTAPERSM:
     return "minctasm";
+  case PROPERTY_MAXNREG:
+    return "maxnreg";
   case PROPERTY_ISTEXTURE:
     return "texture";
   case PROPERTY_ISSURFACE:
     return "surface";
   case PROPERTY_ISSAMPLER:
     return "sampler";
   case PROPERTY_ISREADONLY_IMAGE_PARAM:
     return "rdoimage";

llvm/lib/Target/NVPTX/NVPTXAsmPrinter.cpp

void NVPTXAsmPrinter::emitKernelFunctionDirectives(const Function &F,
 
   if (specified)
     O << ".maxntid " << maxntidx << ", " << maxntidy << ", " << maxntidz
       << "\n";
 
   unsigned mincta;
   if (llvm::getMinCTASm(F, mincta))
     O << ".minnctapersm " << mincta << "\n";
+
+  unsigned maxnreg;
+  if (llvm::getMaxNReg(F, maxnreg))
+    O << ".maxnreg " << maxnreg << "\n";
 }
 
 std::string
 NVPTXAsmPrinter::getVirtualRegisterName(unsigned Reg) const {
   const TargetRegisterClass *RC = MRI->getRegClass(Reg);
 
   std::string Name;
   raw_string_ostream NameStr(Name);

llvm/lib/Target/NVPTX/NVPTXUtilities.h

 bool getMaxNTIDy(const Function &, unsigned &);
 bool getMaxNTIDz(const Function &, unsigned &);
 
 bool getReqNTIDx(const Function &, unsigned &);
 bool getReqNTIDy(const Function &, unsigned &);
 bool getReqNTIDz(const Function &, unsigned &);
 
 bool getMinCTASm(const Function &, unsigned &);
+bool getMaxNReg(const Function &, unsigned &);
 bool isKernelFunction(const Function &);
 
 bool getAlign(const Function &, unsigned index, unsigned &);
 bool getAlign(const CallInst &, unsigned index, unsigned &);
 
 BasicBlock *getParentBlock(Value *v);
 Function *getParentFunction(Value *v);
 void dumpBlock(Value *v, char *blockName);

llvm/lib/Target/NVPTX/NVPTXUtilities.cpp

return findOneNVVMAnnotation(&F, PropertyAnnotationName(PROPERTY_REQNTID_Z),
                                z);
 }
 
 bool getMinCTASm(const Function &F, unsigned &x) {
   return findOneNVVMAnnotation(
       &F, PropertyAnnotationName(PROPERTY_MINNCTAPERSM), x);
 }
 
+bool getMaxNReg(const Function &F, unsigned &x) {
+  return findOneNVVMAnnotation(&F, PropertyAnnotationName(PROPERTY_MAXNREG), x);
+}
+
 bool isKernelFunction(const Function &F) {
   unsigned x = 0;
   bool retval = findOneNVVMAnnotation(
       &F, PropertyAnnotationName(PROPERTY_ISKERNEL_FUNCTION), x);
   if (!retval) {
     // There is no NVVM metadata, check the calling convention
     return F.getCallingConv() == CallingConv::PTX_Kernel;
   }

llvm/test/CodeGen/NVPTX/annotations.ll

 
 ; CHECK: .entry kernel_func_minctasm
 define void @kernel_func_minctasm(float* %a) {
 ; CHECK: .minnctapersm 42
 ; CHECK: ret
   ret void
 }
 
+; CHECK-LABEL: .entry kernel_func_maxnreg
+define void @kernel_func_maxnreg() {
+; CHECK: .maxnreg 1234
+; CHECK: ret
+  ret void
+}
 
 
-!nvvm.annotations = !{!1, !2, !3, !4, !5, !6, !7, !8}
+
+!nvvm.annotations = !{!1, !2, !3, !4, !5, !6, !7, !8, !9, !10}
 
 !1 = !{void (float*)* @kernel_func_maxntid, !"kernel", i32 1}
 !2 = !{void (float*)* @kernel_func_maxntid, !"maxntidx", i32 10, !"maxntidy", i32 20, !"maxntidz", i32 30}
 
 !3 = !{void (float*)* @kernel_func_reqntid, !"kernel", i32 1}
 !4 = !{void (float*)* @kernel_func_reqntid, !"reqntidx", i32 11, !"reqntidy", i32 22, !"reqntidz", i32 33}
 
 !5 = !{void (float*)* @kernel_func_minctasm, !"kernel", i32 1}
 !6 = !{void (float*)* @kernel_func_minctasm, !"minctasm", i32 42}
 
-!7 = !{i64 addrspace(1)* @texture, !"texture", i32 1}
-!8 = !{i64 addrspace(1)* @surface, !"surface", i32 1}
+!7 = !{void ()* @kernel_func_maxnreg, !"kernel", i32 1}
+!8 = !{void ()* @kernel_func_maxnreg, !"maxnreg", i32 1234}
+
+!9 = !{i64 addrspace(1)* @texture, !"texture", i32 1}
+!10 = !{i64 addrspace(1)* @surface, !"surface", i32 1}