[AMDGPU] Do not emit arch dependent macros with unspecified cpu (#80035)

Summary:
Currently, the AMDGPU toolchain accepts not passing `-mcpu` as a means
to create a sort of "generic" IR. The resulting IR will not contain any
target dependent attributes and can then be inserted into another
program via `-mlink-builtin-bitcode` to inherit its attributes.

However, there are a handful of macros that can leak incorrect
information when compiling for an unspecified architecture. Currently,
things like the wavefront size will default to 64, which is actually
variable. We should not expose these macros unless it is known.

clang/docs/HIPSupport.rst

@@ -176,6 +176,10 @@ Predefined Macros
    * - ``HIP_API_PER_THREAD_DEFAULT_STREAM``
      - Alias to ``__HIP_API_PER_THREAD_DEFAULT_STREAM__``. Deprecated.
 
+Note that some architecture specific AMDGPU macros will have default values when 
+used from the HIP host compilation. Other :doc:`AMDGPU macros <AMDGPUSupport>` 
+like ``__AMDGCN_WAVEFRONT_SIZE__`` will default to 64 for example.
+
 Compilation Modes
 =================
 

clang/lib/Basic/Targets/AMDGPU.cpp

@@ -274,30 +274,30 @@ void AMDGPUTargetInfo::getTargetDefines(const LangOptions &Opts,
   else
     Builder.defineMacro("__R600__");
 
-  if (GPUKind != llvm::AMDGPU::GK_NONE) {
-    StringRef CanonName = isAMDGCN(getTriple()) ?
-      getArchNameAMDGCN(GPUKind) : getArchNameR600(GPUKind);
-    Builder.defineMacro(Twine("__") + Twine(CanonName) + Twine("__"));
-    // Emit macros for gfx family e.g. gfx906 -> __GFX9__, gfx1030 -> __GFX10___
-    if (isAMDGCN(getTriple())) {
-      assert(CanonName.starts_with("gfx") && "Invalid amdgcn canonical name");
-      Builder.defineMacro(Twine("__") + Twine(CanonName.drop_back(2).upper()) +
-                          Twine("__"));
-    }
-    if (isAMDGCN(getTriple())) {
-      Builder.defineMacro("__amdgcn_processor__",
-                          Twine("\"") + Twine(CanonName) + Twine("\""));
-      Builder.defineMacro("__amdgcn_target_id__",
-                          Twine("\"") + Twine(*getTargetID()) + Twine("\""));
-      for (auto F : getAllPossibleTargetIDFeatures(getTriple(), CanonName)) {
-        auto Loc = OffloadArchFeatures.find(F);
-        if (Loc != OffloadArchFeatures.end()) {
-          std::string NewF = F.str();
-          std::replace(NewF.begin(), NewF.end(), '-', '_');
-          Builder.defineMacro(Twine("__amdgcn_feature_") + Twine(NewF) +
-                                  Twine("__"),
-                              Loc->second ? "1" : "0");
-        }
+  // Legacy HIP host code relies on these default attributes to be defined.
+  if (GPUKind == llvm::AMDGPU::GK_NONE && !(Opts.HIP && !Opts.CUDAIsDevice))
+    return;
+
+  StringRef CanonName = isAMDGCN(getTriple()) ? getArchNameAMDGCN(GPUKind)
+                                              : getArchNameR600(GPUKind);
+  Builder.defineMacro(Twine("__") + Twine(CanonName) + Twine("__"));
+  // Emit macros for gfx family e.g. gfx906 -> __GFX9__, gfx1030 -> __GFX10___
+  if (isAMDGCN(getTriple()) && Opts.CUDAIsDevice) {
+    assert(CanonName.starts_with("gfx") && "Invalid amdgcn canonical name");
+    Builder.defineMacro(Twine("__") + Twine(CanonName.drop_back(2).upper()) +
+                        Twine("__"));
+    Builder.defineMacro("__amdgcn_processor__",
+                        Twine("\"") + Twine(CanonName) + Twine("\""));
+    Builder.defineMacro("__amdgcn_target_id__",
+                        Twine("\"") + Twine(*getTargetID()) + Twine("\""));
+    for (auto F : getAllPossibleTargetIDFeatures(getTriple(), CanonName)) {
+      auto Loc = OffloadArchFeatures.find(F);
+      if (Loc != OffloadArchFeatures.end()) {
+        std::string NewF = F.str();
+        std::replace(NewF.begin(), NewF.end(), '-', '_');
+        Builder.defineMacro(Twine("__amdgcn_feature_") + Twine(NewF) +
+                                Twine("__"),
+                            Loc->second ? "1" : "0");
       }
     }
   }

clang/test/CodeGenOpenCL/builtins-amdgcn-wave64.cl

@@ -44,6 +44,6 @@ void test_read_exec_hi(global ulong* out) {
   *out = __builtin_amdgcn_read_exec_hi();
 }
 
-#if __AMDGCN_WAVEFRONT_SIZE != 64
+#if defined(__AMDGCN_WAVEFRONT_SIZE__) && __AMDGCN_WAVEFRONT_SIZE__ != 64
 #error Wrong wavesize detected
 #endif

clang/test/Preprocessor/predefined-arch-macros.c

@@ -4294,13 +4294,20 @@
 
 // Begin amdgcn tests ----------------
 
-// RUN: %clang -march=amdgcn -E -dM %s -o - 2>&1 \
+// RUN: %clang -mcpu=gfx803 -E -dM %s -o - 2>&1 \
+// RUN:     -target amdgcn-unknown-unknown \
+// RUN:   | FileCheck -match-full-lines %s -check-prefixes=CHECK_AMDGCN,CHECK_AMDGCN_803
+// RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target amdgcn-unknown-unknown \
-// RUN:   | FileCheck -match-full-lines %s -check-prefix=CHECK_AMDGCN
+// RUN:   | FileCheck -match-full-lines %s -check-prefixes=CHECK_AMDGCN,CHECK_AMDGCN_NONE
 // CHECK_AMDGCN: #define __AMDGCN__ 1
-// CHECK_AMDGCN: #define __HAS_FMAF__ 1
-// CHECK_AMDGCN: #define __HAS_FP64__ 1
-// CHECK_AMDGCN: #define __HAS_LDEXPF__ 1
+// CHECK_AMDGCN_803: #define __HAS_FMAF__ 1
+// CHECK_AMDGCN_803: #define __HAS_FP64__ 1
+// CHECK_AMDGCN_803: #define __HAS_LDEXPF__ 1
+// CHECK_AMDGCN_NONE-NOT: #define __HAS_FMAF__
+// CHECK_AMDGCN_NONE-NOT: #define __HAS_FP64__
+// CHECK_AMDGCN_NONE-NOT: #define __HAS_LDEXPF__
+// CHECK_AMDGCN_NONE-NOT: #define __AMDGCN_WAVEFRONT_SIZE__
 
 // Begin r600 tests ----------------
 
@@ -4316,6 +4323,15 @@
 // CHECK_R600_FP64-DAG: #define __R600__ 1
 // CHECK_R600_FP64-DAG: #define __HAS_FMAF__ 1
 
+// Begin HIP host tests -----------
+
+// RUN: %clang -x hip -E -dM %s -o - 2>&1 --offload-host-only \
+// RUN:     --offload-arch=gfx803 -target x86_64-unknown-linux \
+// RUN:   | FileCheck -match-full-lines %s -check-prefixes=CHECK_HIP_HOST
+// CHECK_HIP_HOST: #define __AMDGCN_WAVEFRONT_SIZE__ 64
+// CHECK_HIP_HOST: #define __AMDGPU__ 1
+// CHECK_HIP_HOST: #define __AMD__ 1
+
 // Begin avr tests ----------------
 
 // RUN: %clang --target=avr -mmcu=atmega328 -E -dM %s -o - 2>&1 \