[HLSL] Add __spirv__ macro

[cassiebeckley]

This macro can be used by HLSL code to detect that it is being compiled for the SPIR-V target.

[cassiebeckley]

@s-perron @Keenuts

[llvmbot]

@llvm/pr-subscribers-clang

Author: Cassandra Beckley (cassiebeckley)

Changes

This macro can be used by HLSL code to detect that it is being compiled for the SPIR-V target.

---

Full diff: https://github.com/llvm/llvm-project/pull/132848.diff

2 Files Affected:

• (modified) clang/lib/Frontend/InitPreprocessor.cpp (+3)
• (modified) clang/test/Preprocessor/predefined-macros-hlsl.hlsl (+4)

diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 1a816cb6269d4..c6d31e890c7f6 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -430,6 +430,9 @@ static void InitializeStandardPredefinedMacros(const TargetInfo &TI,
       unsigned Minor = Version.getMinor().value_or(0);
       Builder.defineMacro("__SHADER_TARGET_MINOR", Twine(Minor));
     }
+    if (TI.getTriple().isSPIRV()) {
+      Builder.defineMacro("__spirv__");
+    }
     return;
   }
   // C++ [cpp.predefined]p1:
diff --git a/clang/test/Preprocessor/predefined-macros-hlsl.hlsl b/clang/test/Preprocessor/predefined-macros-hlsl.hlsl
index cd211713bf892..26bda6b7be167 100644
--- a/clang/test/Preprocessor/predefined-macros-hlsl.hlsl
+++ b/clang/test/Preprocessor/predefined-macros-hlsl.hlsl
@@ -9,6 +9,8 @@
 // RUN: %clang_cc1 %s -E -dM -o - -triple dxil-pc-shadermodel6.0-vertex | FileCheck -match-full-lines %s --check-prefixes=CHECK,VERTEX,NOHALF
 // RUN: %clang_cc1 %s -E -dM -o - -triple dxil-pc-shadermodel6.3-vertex -fnative-half-type | FileCheck -match-full-lines %s --check-prefixes=CHECK,VERTEX,HALF
 
+// RUN: %clang_cc1 %s -E -dM -o - -triple spirv-unknown-vulkan-compute | FileCheck -match-full-lines %s --check-prefixes=CHECK,COMPUTE,NOHALF,SPIRV
+
 // HALF: #define __HLSL_ENABLE_16_BIT 1
 // NOHALF-NOT: __HLSL_ENABLE_16_BIT
 
@@ -34,6 +36,8 @@
 // PIXEL: #define __SHADER_TARGET_STAGE 0
 // VERTEX: #define __SHADER_TARGET_STAGE 1
 
+// SPIRV: #define __spirv__ 1
+
 // RUN: %clang_cc1 -triple dxil-pc-shadermodel6.3-library %s -E -dM -o - -x hlsl -std=hlsl2015 2>&1 | FileCheck -match-full-lines %s --check-prefixes=STD2015
 // STD2015: warning: support for HLSL language version hlsl2015 is incomplete, recommend using hlsl202x instead
 // STD2015: #define __HLSL_VERSION 2015

[s-perron]

Thanks. I was thinking of adding this myself, but it was pushed off. I don't know the best place to put it. I'll let others who know the FE review.

[s-perron]

This is useful because to will match the DXC behaviour, and make code more easier to port. Even if we have __SPIRV__ is to good to have __spirv__.

[AaronBallman]

Hi! I'm wondering why this macro needs to be exposed outside of HLSL given that there's already __SPIRV__ exposed for this exact purpose. These changes turn out to be disruptive in a downstream SYCL implementation (intel/llvm#18219) because of a namespace named __spirv.

[Keenuts]

Hi, I don't think there is an issue with only emitting the __spirv__ macro with HLSL. Sent out #142401