[clang] [llvm] [PPC] Implement BCD assist builtins (PR #101390)

[Lei Huang via llvm-commits]

================
@@ -515,6 +515,16 @@ TARGET_BUILTIN(__builtin_altivec_vctzh, "V8UsV8Us", "", "power9-vector")
 TARGET_BUILTIN(__builtin_altivec_vctzw, "V4UiV4Ui", "", "power9-vector")
 TARGET_BUILTIN(__builtin_altivec_vctzd, "V2ULLiV2ULLi", "", "power9-vector")
 
+// P7 BCD builtins.
+TARGET_BUILTIN(__builtin_cdtbcd, "UiUi", "", "isa-v206-instructions")
+TARGET_BUILTIN(__builtin_cbcdtd, "UiUi", "", "isa-v206-instructions")
+TARGET_BUILTIN(__builtin_addg6s, "UiUiUi", "", "isa-v206-instructions")
----------------
lei137 wrote:

Yes, XL currently have these builtins and `__buitin_ppc_xxx` are implemented to be compat with XL.

https://github.com/llvm/llvm-project/pull/101390