[clang] [llvm] [NVPTX] Add clang builtin for `__nvvm_reflect` intrinsic (PR #81277)

[Joseph Huber via cfe-commits]

https://github.com/jhuber6 created https://github.com/llvm/llvm-project/pull/81277

Summary:
Some recent support made usage of `__nvvm_reflect` more consistent. We
should expose it as an intrinsic rather than forcing users to externally
define the function.


>From 7b97388a5f251684cf4ae69c3b0cae0ff6fe1397 Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Fri, 9 Feb 2024 10:50:20 -0600
Subject: [PATCH] [NVPTX] Add clang builtin for `__nvvm_reflect` intrinsic

Summary:
Some recent support made usage of `__nvvm_reflect` more consistent. We
should expose it as an intrinsic rather than forcing users to externally
define the function.
---
 clang/include/clang/Basic/BuiltinsNVPTX.def | 1 +
 clang/test/CodeGen/builtins-nvptx.c         | 8 ++++++++
 llvm/include/llvm/IR/IntrinsicsNVVM.td      | 5 +++--
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/clang/include/clang/Basic/BuiltinsNVPTX.def b/clang/include/clang/Basic/BuiltinsNVPTX.def
index 7819e71d7fe2aa..8d3c5e69d55cf4 100644
--- a/clang/include/clang/Basic/BuiltinsNVPTX.def
+++ b/clang/include/clang/Basic/BuiltinsNVPTX.def
@@ -159,6 +159,7 @@ BUILTIN(__nvvm_read_ptx_sreg_pm3, "i", "n")
 
 BUILTIN(__nvvm_prmt, "UiUiUiUi", "")
 BUILTIN(__nvvm_exit, "v", "r")
+BUILTIN(__nvvm_reflect, "UicC*", "r")
 TARGET_BUILTIN(__nvvm_nanosleep, "vUi", "n", AND(SM_70, PTX63))
 
 // Min Max
diff --git a/clang/test/CodeGen/builtins-nvptx.c b/clang/test/CodeGen/builtins-nvptx.c
index ad7c27f2d60d26..4dba7670b5c43e 100644
--- a/clang/test/CodeGen/builtins-nvptx.c
+++ b/clang/test/CodeGen/builtins-nvptx.c
@@ -44,6 +44,14 @@ __device__ int read_tid() {
 
 }
 
+__device__ bool reflect() {
+
+// CHECK: call i32 @llvm.nvvm.reflect(ptr {{.*}})
+
+  unsigned x = __nvvm_reflect("__CUDA_ARCH");
+  return x >= 700;
+}
+
 __device__ int read_ntid() {
 
 // CHECK: call i32 @llvm.nvvm.read.ptx.sreg.ntid.x()
diff --git a/llvm/include/llvm/IR/IntrinsicsNVVM.td b/llvm/include/llvm/IR/IntrinsicsNVVM.td
index d825dc82156432..f7b0fe926959b1 100644
--- a/llvm/include/llvm/IR/IntrinsicsNVVM.td
+++ b/llvm/include/llvm/IR/IntrinsicsNVVM.td
@@ -1624,8 +1624,9 @@ def int_nvvm_compiler_error :
 def int_nvvm_compiler_warn :
     Intrinsic<[], [llvm_anyptr_ty], [], "llvm.nvvm.compiler.warn">;
 
-def int_nvvm_reflect :
-  Intrinsic<[llvm_i32_ty], [llvm_anyptr_ty], [IntrNoMem], "llvm.nvvm.reflect">;
+def int_nvvm_reflect : 
+  Intrinsic<[llvm_i32_ty], [llvm_ptr_ty], [IntrNoMem], "llvm.nvvm.reflect">,
+  ClangBuiltin<"__nvvm_reflect">;
 
 // isspacep.{const, global, local, shared}
 def int_nvvm_isspacep_const