[HIP][Clang][Preprocessor][RFC] Add preprocessor support for C++ Parallel Algorithm Offload

[AlexVlx]

Summary

This patch adds the Preprocessor changes needed by the standard algorithm offload feature being proposed here: https://discourse.llvm.org/t/rfc-adding-c-parallel-algorithm-offload-support-to-clang-llvm/72159/1. The verbose documentation is included in the head of the patch series. This change merely adds two macros to inform user space if we are compiling in stdpar mode and, respectively, if the optional allocation interposition mode has been requested, as well as associated minimal tests. The macros can be used by the runtime implementation of offload to drive conditional compilation, and are only defined if the HIP language has been enabled.

[AlexVlx]

Updating this to reflect the outcome of the RFC, which is that this will be added as a HIP extension exclusively.

[yaxunl]

clang/lib/Frontend/InitPreprocessor.cpp

591

We usually prefer defining the macro consistently in host and device compilation to avoid the chance of violation of ODR.

[AlexVlx]

Define the interpose macro iff in interpose mode.

[yaxunl]

LGTM. Thanks

clang/lib/Frontend/InitPreprocessor.cpp

static void InitializeStandardPredefinedMacros(const TargetInfo &TI,
   if (LangOpts.HIP) {
     Builder.defineMacro("__HIP__");
     Builder.defineMacro("__HIPCC__");
     Builder.defineMacro("__HIP_MEMORY_SCOPE_SINGLETHREAD", "1");
     Builder.defineMacro("__HIP_MEMORY_SCOPE_WAVEFRONT", "2");
     Builder.defineMacro("__HIP_MEMORY_SCOPE_WORKGROUP", "3");
     Builder.defineMacro("__HIP_MEMORY_SCOPE_AGENT", "4");
     Builder.defineMacro("__HIP_MEMORY_SCOPE_SYSTEM", "5");
+    if (LangOpts.HIPStdPar) {
+      Builder.defineMacro("__STDPAR__");
+      if (!LangOpts.CUDAIsDevice)
+        Builder.defineMacro("__STDPAR_INTERPOSE_ALLOC__");
+    }
     if (LangOpts.CUDAIsDevice) {
       Builder.defineMacro("__HIP_DEVICE_COMPILE__");
       if (!TI.hasHIPImageSupport()) {
         Builder.defineMacro("__HIP_NO_IMAGE_SUPPORT__", "1");
         // Deprecated.
         Builder.defineMacro("__HIP_NO_IMAGE_SUPPORT", "1");
       }
     }

clang/test/Preprocessor/predefined-macros.c

 
 // RUN: %clang_cc1 %s -E -dM -o - -x hip -triple x86_64-unknown-linux-gnu \
 // RUN:   -fgpu-default-stream=per-thread \
 // RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-PTH
 // RUN: %clang_cc1 %s -E -dM -o - -x hip -triple amdgcn-amd-amdhsa \
 // RUN:   -fcuda-is-device -fgpu-default-stream=per-thread \
 // RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-PTH
 // CHECK-PTH: #define HIP_API_PER_THREAD_DEFAULT_STREAM 1
+
+// RUN: %clang_cc1 %s -E -dM -o - -x hip -stdpar -triple x86_64-unknown-linux-gnu \
+// RUN:   | FileCheck -match-full-lines %s --check-prefix=CHECK-STDPAR
+// CHECK-STDPAR: #define __STDPAR__ 1
+
+// RUN: %clang_cc1 %s -E -dM -o - -x hip -stdpar -stdpar-interpose-alloc \
+// RUN:  -triple x86_64-unknown-linux-gnu | FileCheck -match-full-lines %s \
+// RUN:  --check-prefix=CHECK-STDPAR-INTERPOSE
+// CHECK-STDPAR-INTERPOSE: #define __STDPAR_INTERPOSE_ALLOC__ 1
+// CHECK-STDPAR-INTERPOSE: #define __STDPAR__ 1
+
+// RUN: %clang_cc1 %s -E -dM -o - -x hip -stdpar -stdpar-interpose-alloc \
+// RUN:  -triple amdgcn-amd-amdhsa -fcuda-is-device | FileCheck -match-full-lines \
+// RUN:  %s --check-prefix=CHECK-STDPAR-INTERPOSE-DEV-NEG
+// CHECK-STDPAR-INTERPOSE-DEV-NEG: #define __STDPAR__ 1
+// CHECK-STDPAR-INTERPOSE-DEV-NEG-NOT: #define __STDPAR_INTERPOSE_ALLOC__ 1
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