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[ELF][LLD] Allow reading of more than one FEATURE_1_AND in same object.
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Authored by peter.smith on Jun 4 2019, 9:17 AM.

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Summary

This patch is a follow on from D62853 . Although many relocatable objects will have a single GNU_PROPERTY_X86_FEATURE_1_AND in the .note.gnu.property section it is permissible to have more than one, and there is a test in ld.bfd that uses it. The behavior that ld.bfd follows is to set the feature bit for a relocatable object if any of the GNU_PROPERTY_X86_FEATURE_1_AND have the feature bit set.

The specific test in ld.bfd is https://github.com/bminor/binutils-gdb/blob/master/ld/testsuite/ld-aarch64/property-bti-pac1.s there isn't an X86 equivalent test but the same behaviour can be observed with IBT and SHSTK. I've added a test case for that.

This could be considered a corner case, however it is not known whether tools will just add another GNU_PROPERTY_X86_FEATURE_1_AND rather than find an existing one and add to it.

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