On 8/9/2026 5:59 PM, Matt Turner wrote:
Enable __attribute__((ifunc)) for alpha*-*-linux*, which sets
HAVE_GNU_INDIRECT_FUNCTION=1 and makes targetm.has_ifunc_p() return
true.
No Alpha backend changes are needed -- the generic ifunc machinery in
varasm.cc handles emission, and alpha/elf.h already provides the
required ASM_OUTPUT_TYPE_DIRECTIVE and ASM_OUTPUT_DEF macros.
Rather than defaulting default_gnu_indirect_function to yes in
config.gcc, this follows the riscv*-*-linux* precedent and gates the
default on a toolchain feature test. A plain assembler test would not
be meaningful: %gnu_indirect_function is handled by generic ELF code in
gas and has been accepted for every target for many years. The real
dependency is on the linker emitting R_ALPHA_IRELATIVE, so the test
assembles, links and inspects the relocations with readelf. Without it
the link silently succeeds while producing an ordinary R_ALPHA_JMP_SLOT.
The existing riscv test is generalized to select the expected relocation
name per target so both share one code path. Alpha needs its own test
source because alpha gas reserves .set for setting assembler modes, so
the alias is spelled with '=', matching the target's ASM_OUTPUT_DEF.
Runtime support additionally requires a glibc dynamic linker that
handles the new relocation.
gcc/ChangeLog:
* configure.ac (gcc_cv_irelative_reloc): New variable, set for
riscv*-*-linux* and alpha*-*-linux*. Perform the linker
IRELATIVE check once, driven by it.
* configure: Regenerate.
THanks. I've pushed this to the trunk.
It's not great that we have a hard to test dependency on a newer glibc,
but I don't see a good way to avoid that. In fact, I strongly suspect
my tester will likely fall over. It builds and installs binutils first,
so it's going to find assembler/linker support for ifuncs and enable
them in GCC as a result. But the glibc installed in the docker
container is fairly old at this point (2.33). We shall see by this time
next week :-)
I doubt many folks are building new versions of GCC on alphas, so
hopefully the pain isn't too bad.
jeff
