Fix nits

Author: krzysz00

llvm/lib/Target/AMDGPU/AMDGPULowerKernelArguments.cpp

@@ -120,6 +120,7 @@ static bool lowerKernelArguments(Function &F, const TargetMachine &TM) {
   CallInst *KernArgSegment =
       Builder.CreateIntrinsic(Intrinsic::amdgcn_kernarg_segment_ptr, {}, {},
                               nullptr, F.getName() + ".kernarg.segment");
+  KernArgSegment->addRetAttr(Attribute::NonNull);
   KernArgSegment->addRetAttr(
       Attribute::getWithDereferenceableBytes(Ctx, TotalKernArgSize));
 
@@ -277,7 +278,6 @@ static bool lowerKernelArguments(Function &F, const TargetMachine &TM) {
     }
   }
 
-  KernArgSegment->addRetAttr(Attribute::NonNull);
   KernArgSegment->addRetAttr(
       Attribute::getWithAlignment(Ctx, std::max(KernArgBaseAlign, MaxAlign)));
 

llvm/test/CodeGen/AMDGPU/lower-kernargs.ll

@@ -1121,17 +1121,17 @@ define amdgpu_kernel void @kern_noundef_global_ptr(ptr addrspace(1) noundef %ptr
 ; HSA-NEXT:    [[KERN_NOUNDEF_GLOBAL_PTR_KERNARG_SEGMENT:%.*]] = call nonnull align 16 dereferenceable(264) ptr addrspace(4) @llvm.amdgcn.kernarg.segment.ptr()
 ; HSA-NEXT:    [[PTR_KERNARG_OFFSET:%.*]] = getelementptr inbounds i8, ptr addrspace(4) [[KERN_NOUNDEF_GLOBAL_PTR_KERNARG_SEGMENT]], i64 0
 ; HSA-NEXT:    [[PTR_LOAD:%.*]] = load ptr addrspace(1), ptr addrspace(4) [[PTR_KERNARG_OFFSET]], align 16, !invariant.load [[META1]]
-; HSA-NEXT:    store volatile ptr addrspace(1) [[PTR_LOAD]], ptr addrspace(1) undef, align 8
+; HSA-NEXT:    store volatile ptr addrspace(1) [[PTR_LOAD]], ptr addrspace(1) null, align 8
 ; HSA-NEXT:    ret void
 ;
 ; MESA-LABEL: @kern_noundef_global_ptr(
 ; MESA-NEXT:    [[KERN_NOUNDEF_GLOBAL_PTR_KERNARG_SEGMENT:%.*]] = call nonnull align 16 dereferenceable(264) ptr addrspace(4) @llvm.amdgcn.kernarg.segment.ptr()
 ; MESA-NEXT:    [[PTR_KERNARG_OFFSET:%.*]] = getelementptr inbounds i8, ptr addrspace(4) [[KERN_NOUNDEF_GLOBAL_PTR_KERNARG_SEGMENT]], i64 36
 ; MESA-NEXT:    [[PTR_LOAD:%.*]] = load ptr addrspace(1), ptr addrspace(4) [[PTR_KERNARG_OFFSET]], align 4, !invariant.load [[META1]]
-; MESA-NEXT:    store volatile ptr addrspace(1) [[PTR_LOAD]], ptr addrspace(1) undef, align 8
+; MESA-NEXT:    store volatile ptr addrspace(1) [[PTR_LOAD]], ptr addrspace(1) null, align 8
 ; MESA-NEXT:    ret void
 ;
-  store volatile ptr addrspace(1) %ptr, ptr addrspace(1) undef
+  store volatile ptr addrspace(1) %ptr, ptr addrspace(1) null
   ret void
 }