try this COPR

gcc.spec

@@ -18,7 +18,7 @@
 %global build_ada 0
 %global build_objc 0
 %global build_go 0
-%global build_libgccjit 0
+%global build_libgccjit 1
 %else
 %ifarch %{ix86} x86_64 ia64 ppc %{power64} alpha s390x %{arm} aarch64
 %global build_ada 1
@@ -115,20 +115,23 @@ Group: Development/Languages
 # git --git-dir=gcc-dir.tmp/.git fetch --depth 1 origin %%{gitrev}
 # git --git-dir=gcc-dir.tmp/.git archive --prefix=%%{name}-%%{version}-%%{DATE}/ %%{gitrev} | xz -9e > %%{name}-%%{version}-%%{DATE}.tar.xz
 # rm -rf gcc-dir.tmp
-Source0: gcc-%{version}-%{DATE}.tar.xz
+#Source0: gcc-%{version}-%{DATE}.tar.xz
+Source0: http://ftp.tsukuba.wide.ad.jp/software/gcc/releases/gcc-8.4.0/gcc-8.4.0.tar.xz
 # The source for nvptx-tools package was pulled from upstream's vcs.  Use the
 # following commands to generate the tarball:
 # git clone --depth 1 git://github.com/MentorEmbedded/nvptx-tools.git nvptx-tools-dir.tmp
 # git --git-dir=nvptx-tools-dir.tmp/.git fetch --depth 1 origin %%{nvptx_tools_gitrev}
 # git --git-dir=nvptx-tools-dir.tmp/.git archive --prefix=nvptx-tools-%%{nvptx_tools_gitrev}/ %%{nvptx_tools_gitrev} | xz -9e > nvptx-tools-%%{nvptx_tools_gitrev}.tar.xz
 # rm -rf nvptx-tools-dir.tmp
-Source1: nvptx-tools-%{nvptx_tools_gitrev}.tar.xz
+#Source1: nvptx-tools-%{nvptx_tools_gitrev}.tar.xz
+Source1: https://github.com/MentorEmbedded/nvptx-tools/archive/%{nvptx_tools_gitrev}.tar.gz
 # The source for nvptx-newlib package was pulled from upstream's vcs.  Use the
 # following commands to generate the tarball:
 # git clone git://sourceware.org/git/newlib-cygwin.git newlib-cygwin-dir.tmp
 # git --git-dir=newlib-cygwin-dir.tmp/.git archive --prefix=newlib-cygwin-%%{newlib_cygwin_gitrev}/ %%{newlib_cygwin_gitrev} ":(exclude)newlib/libc/sys/linux/include/rpc/*.[hx]" | xz -9e > newlib-cygwin-%%{newlib_cygwin_gitrev}.tar.xz
 # rm -rf newlib-cygwin-dir.tmp
-Source2: nvptx-newlib-%{nvptx_newlib_gitrev}.tar.xz
+#Source2: nvptx-newlib-%{nvptx_newlib_gitrev}.tar.xz
+Source2: https://github.com/MentorEmbedded/nvptx-newlib/archive/%{nvptx_newlib_gitrev}.tar.gz
 %global isl_version 0.16.1
 URL: http://gcc.gnu.org
 # Need binutils with -pie support >= 2.14.90.0.4-4