disable some LLVM features for amdgpu.

in llvm 13, these generate a bunch of warnings.  the *denormals features
are gone (replaced but i'm unable to use the newer names.)  additinoally,
neither "-xnack" or "+xnack" work anymore.

docs seem to indicate that VI/GFX8 should support +xnack.  the change to
si_init_compiler() was an attempt to avoid the other +xnack usage, but
it does not help.


Index: external/mit/MesaLib.old/dist/src/amd/common/ac_llvm_util.c
===================================================================
RCS file: /cvsroot/xsrc/external/mit/MesaLib.old/dist/src/amd/common/ac_llvm_util.c,v
retrieving revision 1.1.1.1
diff -p -u -r1.1.1.1 ac_llvm_util.c
--- external/mit/MesaLib.old/dist/src/amd/common/ac_llvm_util.c	11 Jul 2021 20:36:22 -0000	1.1.1.1
+++ external/mit/MesaLib.old/dist/src/amd/common/ac_llvm_util.c	29 Aug 2021 22:54:20 -0000
@@ -151,11 +151,12 @@ static LLVMTargetMachineRef ac_create_ta
 	LLVMTargetRef target = ac_get_llvm_target(triple);
 
 	snprintf(features, sizeof(features),
-		 "+DumpCode,-fp32-denormals,+fp64-denormals%s%s%s%s%s%s",
+		 "+DumpCode%s%s%s%s%s%s%s",
+		 HAVE_LLVM >= 0x0B00 ? "" : ",-fp32-denormals,+fp64-denormals",
 		 HAVE_LLVM >= 0x0800 ? "" : ",+vgpr-spilling",
 		 tm_options & AC_TM_SISCHED ? ",+si-scheduler" : "",
-		 tm_options & AC_TM_FORCE_ENABLE_XNACK ? ",+xnack" : "",
-		 tm_options & AC_TM_FORCE_DISABLE_XNACK ? ",-xnack" : "",
+		 (tm_options & AC_TM_FORCE_ENABLE_XNACK) && HAVE_LLVM <= 0x0800 ? ",+xnack" : "",
+		 (tm_options & AC_TM_FORCE_DISABLE_XNACK) && HAVE_LLVM <= 0x0800 ? ",-xnack" : "",
 		 tm_options & AC_TM_PROMOTE_ALLOCA_TO_SCRATCH ? ",-promote-alloca" : "",
 		 tm_options & AC_TM_NO_LOAD_STORE_OPT ? ",-load-store-opt" : "");
 
Index: external/mit/MesaLib.old/dist/src/gallium/drivers/radeonsi/si_pipe.c
===================================================================
RCS file: /cvsroot/xsrc/external/mit/MesaLib.old/dist/src/gallium/drivers/radeonsi/si_pipe.c,v
retrieving revision 1.1.1.2
diff -p -u -r1.1.1.2 si_pipe.c
--- external/mit/MesaLib.old/dist/src/gallium/drivers/radeonsi/si_pipe.c	11 Jul 2021 20:36:27 -0000	1.1.1.2
+++ external/mit/MesaLib.old/dist/src/gallium/drivers/radeonsi/si_pipe.c	29 Aug 2021 22:54:20 -0000
@@ -120,8 +120,8 @@ static void si_init_compiler(struct si_s
 	enum ac_target_machine_options tm_options =
 		(sscreen->debug_flags & DBG(SI_SCHED) ? AC_TM_SISCHED : 0) |
 		(sscreen->debug_flags & DBG(GISEL) ? AC_TM_ENABLE_GLOBAL_ISEL : 0) |
-		(sscreen->info.chip_class >= GFX9 ? AC_TM_FORCE_ENABLE_XNACK : 0) |
-		(sscreen->info.chip_class < GFX9 ? AC_TM_FORCE_DISABLE_XNACK : 0) |
+		(sscreen->info.chip_class >= VI ? AC_TM_FORCE_ENABLE_XNACK : 0) |
+		(sscreen->info.chip_class < VI ? AC_TM_FORCE_DISABLE_XNACK : 0) |
 		(!sscreen->llvm_has_working_vgpr_indexing ? AC_TM_PROMOTE_ALLOCA_TO_SCRATCH : 0) |
 		(sscreen->debug_flags & DBG(CHECK_IR) ? AC_TM_CHECK_IR : 0) |
 		(create_low_opt_compiler ? AC_TM_CREATE_LOW_OPT : 0);