[clang][AMDGPU] precommit test for ballot on Windows

[ssahasra]

The Clang declaration of the wave-64 builtin uses "UL" as the return type, which is interpreted as a 32-bit unsigned integer on Windows. This emits an incorrect LLVM declaration with i32 return type instead of i64. The clang declaration needs to be fixed to use "WU" instead.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Sameer Sahasrabuddhe (ssahasra)

Changes

The Clang declaration of the wave-64 builtin uses "UL" as the return type, which is interpreted as a 32-bit unsigned integer on Windows. This emits an incorrect LLVM declaration with i32 return type instead of i64. The clang declaration needs to be fixed to use "WU" instead.

---

Full diff: https://github.com/llvm/llvm-project/pull/73920.diff

1 Files Affected:

• (added) clang/test/CodeGenHIP/ballot.cpp (+21)

diff --git a/clang/test/CodeGenHIP/ballot.cpp b/clang/test/CodeGenHIP/ballot.cpp
new file mode 100644
index 000000000000000..823b1583a42fc02
--- /dev/null
+++ b/clang/test/CodeGenHIP/ballot.cpp
@@ -0,0 +1,21 @@
+// REQUIRES: amdgpu-registered-target
+// XFAIL: system-windows
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -target-cpu gfx900 -x hip -emit-llvm -fcuda-is-device -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -target-cpu gfx900 -x hip -S -fcuda-is-device -o - %s | FileCheck %s --check-prefix=GFX9
+
+// FIXME: The Clang declaration of the wave-64 builtin uses "UL" as the return
+// type, which is interpreted as a 32-bit unsigned integer on Windows. This
+// emits an incorrect LLVM declaration with i32 return type instead of i64. The
+// clang declaration needs to be fixed to use "WU" instead.
+
+// CHECK-LABEL: @_Z3fooi
+// CHECK: call i64 @llvm.amdgcn.ballot.i64
+
+// GFX9-LABEL: _Z3fooi:
+// GFX9: v_cmp_ne_u32_e64
+
+#define __device__ __attribute__((device))
+
+__device__ unsigned long long foo(int p) {
+  return __builtin_amdgcn_ballot_w64(p);
+}

[vpykhtin]

Is it really needed to test codegen here?

Nice find, BTW.

[ssahasra]

Yeah, we should check codegen because ultimately that was the symptom ... llc crashed when running hipcc on Windows.

[vpykhtin]

LGTM, thanks!