[llvm] [AMDGPU][Attributor] Infer `inreg` attribute in `AMDGPUAttributor` (PR #101609)

[Matt Arsenault via llvm-commits]

================
@@ -0,0 +1,97 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature --check-globals
+; RUN: opt -S -mtriple=amdgcn-unknown-unknown -passes=amdgpu-attributor %s -o - | FileCheck %s
+
+ at g1 = protected addrspace(1) externally_initialized global i32 0, align 4
+ at g2 = protected addrspace(1) externally_initialized global i32 0, align 4
+ at g3 = protected addrspace(1) externally_initialized global i32 0, align 4
+ at g4 = protected addrspace(1) externally_initialized global i32 0, align 4
+
+;.
+; CHECK: @g1 = protected addrspace(1) externally_initialized global i32 0, align 4
+; CHECK: @g2 = protected addrspace(1) externally_initialized global i32 0, align 4
+; CHECK: @g3 = protected addrspace(1) externally_initialized global i32 0, align 4
+; CHECK: @g4 = protected addrspace(1) externally_initialized global i32 0, align 4
+;.
+define internal fastcc void @callee_infer(ptr addrspace(1) %x, i32 %y) {
+; CHECK-LABEL: define {{[^@]+}}@callee_infer
+; CHECK-SAME: (ptr addrspace(1) inreg [[X:%.*]], i32 inreg [[Y:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[X_VAL:%.*]] = load i32, ptr addrspace(1) [[X]], align 4
+; CHECK-NEXT:    store i32 [[X_VAL]], ptr addrspace(1) @g3, align 4
+; CHECK-NEXT:    store i32 [[Y]], ptr addrspace(1) @g4, align 4
+; CHECK-NEXT:    ret void
+;
+entry:
+  %x.val = load i32, ptr addrspace(1) %x, align 4
+  store i32 %x.val, ptr addrspace(1) @g3, align 4
+  store i32 %y, ptr addrspace(1) @g4, align 4
+  ret void
+}
+
+define protected amdgpu_kernel void @kernel_infer(ptr addrspace(1) %p1, ptr addrspace(1) %p2, i32 %x) {
----------------
arsenm wrote:

Don't need protected? 

https://github.com/llvm/llvm-project/pull/101609