Update comments and cpu feature test

1 files changed, 17 insertions, 14 deletions

diff --git a/TestPrograms/test_ppc_power9.cxx b/TestPrograms/test_ppc_power9.cxx
index 82e1e755..38e87398 100644
--- a/TestPrograms/test_ppc_power9.cxx
+++ b/TestPrograms/test_ppc_power9.cxx
@@ -1,6 +1,20 @@
+// The problem we have here is, it appears only GCC 7.0 and above

+// support Power9 builtins. Clang 7.0 has support for some (all?)

+// assembly instructions but we don't see builtin support. We can't

+// determine the state of XLC. Searching IBM's website for

+// terms like 'darn' 'random number' is returning irrelevant hits.

+// Searching with Google from the outside returns 0 hits.

+//

+// The support disconnect means we may report Power9 as unavailable

+// and support DARN at the same time. We get into that state because

+// we use inline asm to detect DARN availablity in the compiler.

+// Also see cpu.cpp and the two query functions; and ppc_power9.cpp

+// and the two probe functions.

+

 #include <altivec.h>

 int main(int argc, char* argv[])

 {

+#if 0

 	const unsigned char b = (unsigned char)argc;

 	const unsigned int r = (0xf << 24) | (0x3 << 16) | (0xf << 8) | (0x3 << 0);

 #if defined(__clang__)

@@ -10,23 +24,12 @@ int main(int argc, char* argv[])
 #else

 	int XXX[-1];

 #endif

+#endif

 

-#if UINTPTR_MAX == 0xffffffffffffffffULL

-#  if defined(__clang__)

-	unsigned long long y = __builtin_altivec_darn();

-#  elif defined(__GNUC__)

-	unsigned long long y = __builtin_darn();

-#  else

-	int XXX[-1];

-#  endif

-#else

-#  if defined(__clang__)

-	unsigned int y = __builtin_altivec_darn_32();

-#  elif defined(__GNUC__)

+#if defined(__GNUC__) || defined(__IBM_GCC_ASM)

 	unsigned int y = __builtin_darn_32();

-#  else

+#else

 	int XXX[-1];

-#  endif

 #endif

 

 	return 0;