Introduce __CHERI_HYBRID__ macro

This is meant to replace expressions like:
    __has_feature(capabilities) && !defined(__CHERI_PURE_CAPABILITY__)
or (currently(
    __CHERI__ && !defined(__CHERI_PURE_CAPABILITY__)

Author: brooksdavis

clang/lib/Frontend/InitPreprocessor.cpp

@@ -1148,6 +1148,8 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
       if (LangOpts.getCheriBounds() > LangOptions::CBM_Conservative)
         Builder.defineMacro("__CHERI_SUBOBJECT_BOUNDS__",
                             Twine(LangOpts.getCheriBounds()));
+    } else {
+      Builder.defineMacro("__CHERI_HYBRID__");
     }
   }
 

clang/test/Preprocessor/cheri-cap-sizes.c

@@ -39,6 +39,7 @@
 // PURECAP: #define __CHERI_PURE_CAPABILITY__ 2
 // MIPS-NOT: __CHERI_PURE_CAPABILITY__
 // CHECK: #define __CHERI__ 1
+// MIPS: #define __CHERI_HYBRID__ 1
 // Note: 64-bit range for intcap makes more sense than the full range for pointers
 // CHECK: #define __INTCAP_MAX__ 9223372036854775807L
 

clang/test/Preprocessor/cheri-features.c

@@ -32,6 +32,15 @@ void* __capability y = 0;
 // CHECK-MIPS: warning: __CHERI__ not defined
 #endif
 
+#if defined(__CHERI_HYBRID__)
+#pragma message("__CHERI_HYBRID__ defined")
+// CHECK-CHERI: warning: __CHERI_HYBRID__ defined
+void* __capability y = 0;
+#else
+#pragma message("__CHERI_HYBRID__ not defined")
+// CHECK-MIPS: warning: __CHERI_HYBRID__ not defined
+#endif
+
 int main() {
 	return 0;
 }

clang/test/Preprocessor/cheri-riscv-feature-flags.c

@@ -19,6 +19,7 @@
 // CHECK: #define __CHERI_CAP_PERMISSION_PERMIT_STORE__ 8
 // CHECK: #define __CHERI_CAP_PERMISSION_PERMIT_UNSEAL__ 512
 // CHECK: #define __CHERI__ 1
+// CHECK: #define __CHERI_HYBRID__ 1
 // CHECK32: #define __SIZEOF_CHERI_CAPABILITY__ 8
 // CHECK64: #define __SIZEOF_CHERI_CAPABILITY__ 16
 // __VERSION__ and __clang_version__ could contain CHERI due to the Git URL.

clang/test/Preprocessor/init.c

@@ -435,6 +435,7 @@
 // CHERI-COMMON-NEXT: #define __CHERI_CAP_PERMISSION_PERMIT_STORE__ 8
 // CHERI-COMMON-NEXT: #define __CHERI_CAP_PERMISSION_PERMIT_UNSEAL__ 512
 // CHERI-COMMON-NEXT: #define __CHERI__ 1
+// CHERI-COMMON-NEXT: #define __CHERI_HYBRID__ 1
 // CHERI64:           #define __POINTER_WIDTH__ 32
 // CHERI128:          #define __POINTER_WIDTH__ 64
 // CHERI-COMMON-NEXT: #define __PRAGMA_REDEFINE_EXTNAME 1

libcxx/test/std/utilities/function.objects/unord.hash/integral.pass.cpp

@@ -126,9 +126,9 @@ int main(int, char**)
     test<__uint128_t>();
 #endif
 
-#if defined(__CHERI__) && !defined(__CHERI_PURE_CAPABILITY__)
-  test<__intcap_t>();
-  test<__uintcap_t>();
+#ifdef __CHERI_HYBRID__
+    test<__intcap_t>();
+    test<__uintcap_t>();
 #endif
 
   return 0;