[clang] [Clang][AMDGPU] Accept builtins in lambda declarations (PR #135027)

[Juan Manuel Martinez Caamaño via cfe-commits]

https://github.com/jmmartinez created https://github.com/llvm/llvm-project/pull/135027

`Sema::getCurFunctionDecl(AllowLambda = false)` returns a nullptr when the lambda declaration is outside a function (for example, when assigning a lambda to a static constexpr variable).

This triggered an assertion in `SemaAMDGPU::CheckAMDGCNBuiltinFunctionCall`.

Using `Sema::getCurFunctionDecl(AllowLambda = true)` returns the declaration of the enclosing lambda.

Stumbled with this issue when refactoring some code in CK.

>From 4e5736d1b90ae477642ea03dcf39231f5f0a8e59 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Manuel=20Martinez=20Caama=C3=B1o?= <juamarti at amd.com>
Date: Wed, 9 Apr 2025 15:11:19 +0200
Subject: [PATCH] [Clang][AMDGPU] Accept builtins in lambda declarations

Sema::getCurFunctionDecl(AllowLambda = false) returns a nullptr when the
lambda declaration is outside a function (for example, when used in an
assignment).

Using Sema::getCurFunctionDecl(AllowLambda = true) returns the
declaration of the enclosing lambda.
---
 clang/lib/Sema/SemaAMDGPU.cpp                 |  2 +-
 .../test/SemaHIP/amdgpu-builtin-in-lambda.hip | 24 +++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 clang/test/SemaHIP/amdgpu-builtin-in-lambda.hip

diff --git a/clang/lib/Sema/SemaAMDGPU.cpp b/clang/lib/Sema/SemaAMDGPU.cpp
index 7fec099374152..af139e36dd2ed 100644
--- a/clang/lib/Sema/SemaAMDGPU.cpp
+++ b/clang/lib/Sema/SemaAMDGPU.cpp
@@ -27,7 +27,7 @@ bool SemaAMDGPU::CheckAMDGCNBuiltinFunctionCall(unsigned BuiltinID,
   // position of memory order and scope arguments in the builtin
   unsigned OrderIndex, ScopeIndex;
 
-  const auto *FD = SemaRef.getCurFunctionDecl();
+  const auto *FD = SemaRef.getCurFunctionDecl(true);
   assert(FD && "AMDGPU builtins should not be used outside of a function");
   llvm::StringMap<bool> CallerFeatureMap;
   getASTContext().getFunctionFeatureMap(CallerFeatureMap, FD);
diff --git a/clang/test/SemaHIP/amdgpu-builtin-in-lambda.hip b/clang/test/SemaHIP/amdgpu-builtin-in-lambda.hip
new file mode 100644
index 0000000000000..7a47fbd39817e
--- /dev/null
+++ b/clang/test/SemaHIP/amdgpu-builtin-in-lambda.hip
@@ -0,0 +1,24 @@
+// REQUIRES: amdgpu-registered-target
+// RUN: %clang_cc1 -std=c++20 -triple amdgcn -target-cpu tahiti -fsyntax-only -fcuda-is-device -verify=expected -o - %s
+// RUN: %clang_cc1 -std=c++20 -triple amdgcn -target-cpu gfx950 -fsyntax-only -fcuda-is-device -o - %s
+
+#define __device__ __attribute__((device))
+#define __shared__ __attribute__((shared))
+
+struct S {
+    static constexpr auto make_buffer_rsrc_lambda = [](void *p, short stride, int num, int flags) {
+        return __builtin_amdgcn_make_buffer_rsrc(p, stride, num, flags);
+    };
+
+    static constexpr auto global_load_lds_lambda = [](void* src, __shared__ void *dst) {
+        __builtin_amdgcn_global_load_lds(src, dst, 16, 0, 0); // expected-error{{invalid size value}} expected-note{{size must be 1, 2, or 4}}
+    };
+};
+
+__device__ __amdgpu_buffer_rsrc_t test_simple_builtin(void *p, short stride, int num, int flags) {
+    return S::make_buffer_rsrc_lambda(p, stride, num, flags);
+}
+
+__device__ void test_target_dependant_builtin(void *src, __shared__ void *dst) {
+    S::global_load_lds_lambda(src, dst);
+}