[clang] [Clang] Add macro for `__VULKAN__` environment (PR #196103)

[Joseph Huber via cfe-commits]

https://github.com/jhuber6 created https://github.com/llvm/llvm-project/pull/196103

Summary:
Adds a macro like for `__LINUX__` or `__WIN32`. The intention here is to
let code differentiate between vulkan variants or not.


>From 054928cb381c171a700c89c95c92a4141e5c9875 Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Wed, 6 May 2026 10:59:29 -0500
Subject: [PATCH] [Clang] Add macro for `__VULKAN__` environment

Summary:
Adds a macro like for `__LINUX__` or `__WIN32`. The intention here is to
let code differentiate between vulkan variants or not.
---
 clang/lib/Basic/Targets/SPIR.cpp            | 2 ++
 clang/test/Preprocessor/predefined-macros.c | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/clang/lib/Basic/Targets/SPIR.cpp b/clang/lib/Basic/Targets/SPIR.cpp
index e55a6ed8bc63f..b6d6b213d78ed 100644
--- a/clang/lib/Basic/Targets/SPIR.cpp
+++ b/clang/lib/Basic/Targets/SPIR.cpp
@@ -89,6 +89,8 @@ void BaseSPIRVTargetInfo::getTargetDefines(const LangOptions &Opts,
   DefineStd(Builder, "SPIRV", Opts);
   if (Opts.HLSL)
     DefineStd(Builder, "spirv", Opts);
+  if (getTriple().isVulkanOS())
+    Builder.defineMacro("__VULKAN__");
 }
 
 void SPIRVTargetInfo::getTargetDefines(const LangOptions &Opts,
diff --git a/clang/test/Preprocessor/predefined-macros.c b/clang/test/Preprocessor/predefined-macros.c
index 8dbb477be4c5d..ab85cfc00b42a 100644
--- a/clang/test/Preprocessor/predefined-macros.c
+++ b/clang/test/Preprocessor/predefined-macros.c
@@ -238,6 +238,13 @@
 // CHECK-SPIRV64-NOT: #define __SPIRV32__ 1
 // CHECK-SPIRV64-NOT: #define __spirv__ 1
 
+// RUN: %clang_cc1 %s -E -dM -o - -x c -triple spirv64-unknown-vulkan \
+// RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-SPIRV64-VULKAN
+// CHECK-SPIRV64-VULKAN-DAG: #define __SPIRV__ 1
+// CHECK-SPIRV64-VULKAN-DAG: #define __SPIRV64__ 1
+// CHECK-SPIRV64-VULKAN-DAG: #define __VULKAN__ 1
+// CHECK-SPIRV64-VULKAN-NOT: #define __SPIRV32__ 1
+
 // RUN: %clang_cc1 %s -E -dM -o - -x cl -triple spirv64-amd-amdhsa \
 // RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-SPIRV64-AMDGCN
 // RUN: %clang_cc1 %s -E -dM -o - -x cl -triple spirv64-amd-amdhsa -fatomic-ignore-denormal-mode \