[NVPTX] Add a clang builtin for the warpsize intrinsic

[jhuber6]

Summary:
There's an intrinsic for the warp size, we want to expose this to make
the interface proposed in
#110179 more generic.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Joseph Huber (jhuber6)

Changes

Summary:
There's an intrinsic for the warp size, we want to expose this to make
the interface proposed in
#110179 more generic.

---

Full diff: https://github.com/llvm/llvm-project/pull/110316.diff

2 Files Affected:

• (modified) clang/include/clang/Basic/BuiltinsNVPTX.def (+1)
• (modified) clang/test/CodeGen/builtins-nvptx.c (+3-1)

diff --git a/clang/include/clang/Basic/BuiltinsNVPTX.def b/clang/include/clang/Basic/BuiltinsNVPTX.def
index 6fff562165080a..6b7bce5bc00d4f 100644
--- a/clang/include/clang/Basic/BuiltinsNVPTX.def
+++ b/clang/include/clang/Basic/BuiltinsNVPTX.def
@@ -139,6 +139,7 @@ TARGET_BUILTIN(__nvvm_is_explicit_cluster, "b", "nc", AND(SM_90, PTX78))
 BUILTIN(__nvvm_read_ptx_sreg_laneid, "i", "nc")
 BUILTIN(__nvvm_read_ptx_sreg_warpid, "i", "nc")
 BUILTIN(__nvvm_read_ptx_sreg_nwarpid, "i", "nc")
+BUILTIN(__nvvm_read_ptx_sreg_warpsize, "i", "nc")
 
 BUILTIN(__nvvm_read_ptx_sreg_smid, "i", "nc")
 BUILTIN(__nvvm_read_ptx_sreg_nsmid, "i", "nc")
diff --git a/clang/test/CodeGen/builtins-nvptx.c b/clang/test/CodeGen/builtins-nvptx.c
index bfa72e8bd69454..0d0e3ecdb90c9e 100644
--- a/clang/test/CodeGen/builtins-nvptx.c
+++ b/clang/test/CodeGen/builtins-nvptx.c
@@ -114,6 +114,7 @@ __device__ int read_ids() {
 // CHECK: call i32 @llvm.nvvm.read.ptx.sreg.smid()
 // CHECK: call i32 @llvm.nvvm.read.ptx.sreg.nsmid()
 // CHECK: call i32 @llvm.nvvm.read.ptx.sreg.gridid()
+// CHECK: call i32 @llvm.nvvm.read.ptx.sreg.warpsize()
 
   int a = __nvvm_read_ptx_sreg_laneid();
   int b = __nvvm_read_ptx_sreg_warpid();
@@ -121,8 +122,9 @@ __device__ int read_ids() {
   int d = __nvvm_read_ptx_sreg_smid();
   int e = __nvvm_read_ptx_sreg_nsmid();
   int f = __nvvm_read_ptx_sreg_gridid();
+  int g = __nvvm_read_ptx_sreg_warpsize();
 
-  return a + b + c + d + e + f;
+  return a + b + c + d + e + f + g;
 
 }
 

[jlebar]

sgtm