Bootstrap LLVM 15 on riscv64

Signed-off-by: David Abdurachmanov <davidlt@rivosinc.com>

llvm.spec

@@ -1,6 +1,8 @@
 # We are building with clang for faster/lower memory LTO builds.
 # See https://docs.fedoraproject.org/en-US/packaging-guidelines/#_compiler_macros
+%ifnarch riscv64
 %global toolchain clang
+%endif
 
 # Components enabled if supported by target architecture:
 %define gold_arches %{ix86} x86_64 %{arm} aarch64 %{power64} s390x
@@ -11,7 +13,11 @@
 %endif
 
 %bcond_with compat_build
+%ifnarch riscv64
 %bcond_without check
+%else
+%bcond_with check
+%endif
 
 #global rc_ver 3
 %global maj_ver 15
@@ -225,14 +231,14 @@ mv %{cmake_srcdir} cmake
 
 %build
 
-%ifarch s390 s390x
+%ifarch s390 s390x riscv64
 # Fails with "exceeded PCRE's backtracking limit"
 %global _lto_cflags %nil
 %else
 %global _lto_cflags -flto=thin
 %endif
 
-%ifarch s390 s390x %{arm} %ix86
+%ifarch s390 s390x %{arm} %ix86 riscv64
 # Decrease debuginfo verbosity to reduce memory consumption during final library linking
 %global optflags %(echo %{optflags} | sed 's/-g /-g1 /')
 %endif
@@ -243,7 +249,7 @@ mv %{cmake_srcdir} cmake
 	-DLLVM_PARALLEL_LINK_JOBS=1 \
 	-DCMAKE_BUILD_TYPE=RelWithDebInfo \
 	-DCMAKE_SKIP_RPATH:BOOL=ON \
-%ifarch s390 %{arm} %ix86
+%ifarch s390 %{arm} %ix86 risv64
 	-DCMAKE_C_FLAGS_RELWITHDEBINFO="%{optflags} -DNDEBUG" \
 	-DCMAKE_CXX_FLAGS_RELWITHDEBINFO="%{optflags} -DNDEBUG" \
 %endif
@@ -565,6 +571,12 @@ fi
 %endif
 
 %changelog
+* Tue Oct 04 2022 David Abdurachmanov <davidlt@rivosinc.com> - 15.0.0-1.0.riscv64
+- Disable tests on riscv64 for now
+- Disable LTO on riscv64 (there is no thin LTO in GCC)
+- Build with GCC (bootstrapping)
+- Lower memory consumption on riscv64
+
 * Tue Sep 06 2022 Nikita Popov <npopov@redhat.com> - 15.0.0-1
 - Update to LLVM 15.0.0