On 27/12/2024 21:47, Thiago Jung Bauermann wrote:
> In 32-bit Arm assembly, the @ character is the start of a comment so
> the section type needs to use the % character instead.
>
> configure.ac attempts to account for this difference by doing a second
> try when checking the assembler for section merging support.
> Unfortunately there is a bug: because the gcc_GAS_CHECK_FEATURE macro
> has a call to AC_CACHE_CHECK, it will actually skip the second try
> because the gcc_cv_as_shf_merge variable has already been set:
>
> checking assembler for section merging support... no
> checking assembler for section merging support... (cached) no
>
> Fix by using a separate variable for the second try, as is done in the
> check for COMDAT group support.
>
> This problem was noticed because the recent binutils commit
> d5cbf916be4a ("gas/ELF: also reject merge entity size being zero") caused
> gas to be stricter about mergeable sections without an entity size:
>
> configure:27013: checking assembler for section merging support
> configure:27022: /path/to/as --fatal-warnings -o conftest.o conftest.s >&5
> conftest.s: Assembler messages:
> conftest.s:1: Warning: invalid merge / string entity size
> conftest.s: Error: 1 warning, treating warnings as errors
> configure:27025: $? = 1
> configure: failed program was
> .section .rodata.str, "aMS", @progbits, 1
> configure:27036: result: no
>
> In previous versions of gas the conftest.s program above was accepted
> and configure detected support for section merging.
>
> See also:
> https://linaro.atlassian.net/browse/GNU-1427
> https://sourceware.org/bugzilla/show_bug.cgi?id=32491
>
> Tested on armv8l-linux-gnueabihf.
>
> gcc/ChangeLog:
> * configure.ac: Fix check for HAVE_GAS_SHF_MERGE on Arm targets.
> * configure: Regenerate.
OK.
R.
