Fix 64-bit BFD detection causing build failures

We have a discrepancy with 64-bit BFD handling across our component
subdirectories leading to link failures such as:

ld: ../opcodes/.libs/libopcodes.a(disassemble.o): in function `disassembler': disassemble.c:(.text+0x65): undefined reference to `print_insn_alpha'
ld: disassemble.c:(.text+0x105): undefined reference to `print_insn_ia64'
ld: disassemble.c:(.text+0x11d): undefined reference to `print_insn_loongarch'
ld: disassemble.c:(.text+0x1a1): undefined reference to `print_insn_big_mips'
[...]

with some configurations having a 32-bit host and 64-bit BFD, such as:
`--host=i386-linux-gnu --target=riscv64-linux-gnu --enable-targets=all'.
This is ultimately due to how 64-bit BFD is enabled for bfd/ itself and
other subdirectorses and has been a regression from commit 1d5269c994bf
("unify 64-bit bfd checks").

For bfd/ the BFD_64_BIT autoconf macro from config/bfd64.m4 is used
combined with this logic in bfd/configure.ac:

case ${host64}-${target64}-${want64} in
  *true*)
    wordsize=64
    bfd64_libs='$(BFD64_LIBS)'
    all_backends='$(BFD64_BACKENDS) $(BFD32_BACKENDS)'
    [...]
    ;;
  false-false-false)
    wordsize=32
    all_backends='$(BFD32_BACKENDS)'
    ;;
esac

where the value of ${wordsize} switches between 32-bit and 64-bit BFD
via these pieces:

#define BFD_ARCH_SIZE @wordsize@

and:

#if BFD_ARCH_SIZE >= 64
#define BFD64
#endif

in bfd/bfd-in.h, which ultimately becomes a part of "bfd.h".

Then ${host64} is determined in bfd/configure.ac from the host's word
size, via the host's pointer size:

if test "x${ac_cv_sizeof_void_p}" = "x8"; then
  host64=true
fi

And ${target64} is determined in bfd/configure.ac from the target's word
size:

    if test ${target_size} = 64; then
	target64=true
    fi

Where multiple targets have been requested with `--enable-targets=all'
the presence of any 64-bit target will set "true" here.

Finally ${want64} is set according to `--enable-64-bit-bfd' user option
with an arrangement involving BFD_64_BIT:

BFD_64_BIT
if test $enable_64_bit_bfd = yes ; then
  want64=true
else
  want64=false
fi

which also, redundantly, checks and sets its result upon the host's word
size.  Lastly ${want64} is also selectively set by target fragments in
bfd/config.bfd, which mostly if not completely overlaps with ${target64}
setting as described above.

Conversely other subdirectories only rely on BFD_64_BIT, so they fail to
notice that BFD is 64-bit and do not enable their 64-bit handling where
the host requested is 32-bit and 64-bit BFD has been enabled other than
with `--enable-64-bit-bfd'.  One consequence is opcodes/disassemble.c
enables calls to its numerous own 64-bit backends by checking the BFD64
macro from "bfd.h", however does not actually enable said backends in
its Makefile.  Hence the link errors quoted above.

Address the problem then by moving the `--enable-64-bit-bfd' option back
to bfd/configure.ac and remove the call to BFD_64_BIT from there and
then rewrite the macro in terms of checking for the presence of BFD64
macro in "bfd.h", which is the canonical way of determining whether BFD
is 64-bit or not.

Rather than running `grep' directly on ../bfd/bfd-in3.h as the opcodes/
fragment used to before the problematic commit:

    if grep '#define BFD_ARCH_SIZE 64' ../bfd/bfd-in3.h > /dev/null; then

run the preprocessor on "bfd.h", which allows to invoke the macro from
configure.ac files placed in subdirectories located at deeper levels, by
relying on the preprocessor's search path.

This requires however that the invokers rely on `all-bfd' rather than
`configure-bfd' for their `configure' invocation stage, because "bfd.h"
is made by `make all' rather than `configure' in bfd/.

Do not cache the result of this check however, as reconfiguring a tree
such as to flip `--enable-64-bit-bfd' on or to change a secondary target
may affect BFD64 and we have no access to information about secondary
targets in BFD_64_BIT.

Also remove the ENABLE_BFD_64_BIT automake conditional, as it's not used
anywhere.

Last but not least remove the hack from gdb/configure.ac to fail builds
for `mips*-*-*' hosts where `--enable-targets=all' has been requested,
but `--enable-64-bit-bfd' has not as it's no longer needed.  Such builds
complete successfully now, having enabled 64-bit BFD implicitly.

Tested-By: Guinevere Larsen <guinevere@redhat.com>
Tested-By: Luis Machado <luis.machado@arm.com>
Approved-By: Alan Modra <amodra@gmail.com>
Approved-By: Luis Machado <luis.machado@arm.com>

0 files changed, 0 insertions, 0 deletions