amdgcn: deprecate Fiji device and multilib

LLVM wants to remove it, which breaks our build.  This patch means that
most users won't notice that change, when it comes, and those that do will
have chosen to enable Fiji explicitly.

I'm selecting gfx900 as the new default as that's the least likely for users
to want, which means most users will specify -march explicitly, which means
we'll be free to change the default again, when we need to, without breaking
anybody's makefiles.

gcc/ChangeLog:

	* config.gcc (amdgcn): Switch default to --with-arch=gfx900.
	Implement support for --with-multilib-list.
	* config/gcn/t-gcn-hsa: Likewise.
	* doc/install.texi: Likewise.
	* doc/invoke.texi: Mark Fiji deprecated.

4 files changed, 39 insertions, 6 deletions

diff --git a/gcc/config.gcc b/gcc/config.gcc
index 37311fc..9c39715 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -4538,7 +4538,19 @@ case "${target}" in
 				;;
 			esac
 		done
-		[ "x$with_arch" = x ] && with_arch=fiji
+		[ "x$with_arch" = x ] && with_arch=gfx900
+
+		case "x${with_multilib_list}" in
+		x | xno)
+			TM_MULTILIB_CONFIG=
+			;;
+		xdefault | xyes)
+			TM_MULTILIB_CONFIG=`echo "gfx900,gfx906,gfx908,gfx90a" | sed "s/${with_arch},\?//;s/,$//"`
+			;;
+		*)
+			TM_MULTILIB_CONFIG="${with_multilib_list}"
+			;;
+		esac
 		;;
 
 	hppa*-*-*)
diff --git a/gcc/config/gcn/t-gcn-hsa b/gcc/config/gcn/t-gcn-hsa
index ea27122..18db707 100644
--- a/gcc/config/gcn/t-gcn-hsa
+++ b/gcc/config/gcn/t-gcn-hsa
@@ -42,8 +42,12 @@ ALL_HOST_OBJS += gcn-run.o
 gcn-run$(exeext): gcn-run.o
 	+$(LINKER) $(ALL_LINKERFLAGS) $(LDFLAGS) -o $@ $< -ldl
 
-MULTILIB_OPTIONS = march=gfx900/march=gfx906/march=gfx908/march=gfx90a
-MULTILIB_DIRNAMES = gfx900 gfx906 gfx908 gfx90a
+empty :=
+space := $(empty) $(empty)
+comma := ,
+multilib_list := $(subst $(comma),$(space),$(TM_MULTILIB_CONFIG)) 
+MULTILIB_OPTIONS = $(subst $(space),/,$(addprefix march=,$(multilib_list)))
+MULTILIB_DIRNAMES = $(multilib_list)
 
 gcn-tree.o: $(srcdir)/config/gcn/gcn-tree.cc
 	$(COMPILE) $<
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 31f2234..4035e80 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -1236,8 +1236,8 @@ sysv, aix.
 @itemx --without-multilib-list
 Specify what multilibs to build.  @var{list} is a comma separated list of
 values, possibly consisting of a single value.  Currently only implemented
-for aarch64*-*-*, arm*-*-*, loongarch*-*-*, riscv*-*-*, sh*-*-* and
-x86-64-*-linux*.  The accepted values and meaning for each target is given
+for aarch64*-*-*, amdgcn*-*-*, arm*-*-*, loongarch*-*-*, riscv*-*-*, sh*-*-*
+and x86-64-*-linux*.  The accepted values and meaning for each target is given
 below.
 
 @table @code
@@ -1250,6 +1250,15 @@ default run-time library will be built.  If @var{list} is
 default set of libraries is selected based on the value of
 @option{--target}.
 
+@item amdgcn*-*-*
+@var{list} is a comma separated list of ISA names (allowed values: @code{fiji},
+@code{gfx900}, @code{gfx906}, @code{gfx908}, @code{gfx90a}). It ought not
+include the name of the default ISA, specified via @option{--with-arch}.  If
+@var{list} is empty, then there will be no multilibs and only the default
+run-time library will be built.  If @var{list} is @code{default} or
+@option{--with-multilib-list=} is not specified, then the default set of
+libraries is selected.
+
 @item arm*-*-*
 @var{list} is a comma separated list of @code{aprofile} and
 @code{rmprofile} to build multilibs for A or R and M architecture
@@ -3922,6 +3931,12 @@ To run the binaries, install the HSA Runtime from the
 @file{libexec/gcc/amdhsa-amdhsa/@var{version}/gcn-run} to launch them
 on the GPU.
 
+To enable support for GCN3 Fiji devices (gfx803), GCC has to be configured with
+@option{--with-arch=@code{fiji}} or
+@option{--with-multilib-list=@code{fiji},...}.  Note that support for Fiji
+devices has been removed in ROCm 4.0 and support in LLVM is deprecated and will
+be removed in the future.
+
 @html
 <hr />
 @end html
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 9b5ff45..8bbe113 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -21097,7 +21097,9 @@ are
 
 @table @samp
 @item fiji
-Compile for GCN3 Fiji devices (gfx803).
+Compile for GCN3 Fiji devices (gfx803).  Support deprecated; availablility
+depends on how GCC has been configured, see @option{--with-arch} and
+@option{--with-multilib-list}.
 
 @item gfx900
 Compile for GCN5 Vega 10 devices (gfx900).