Always use adr with __thumb2__.
Thumb2 addresses are a bit a mess, depending on whether a label is interpreted as a function pointer value (for use with BX and BLX) or as a program counter value (for use with PC-relative addressing). Clang's integrated assembler mis-assembles this code. See https://crbug.com/124610#c54 for details. Instead, use the ADR pseudo-instruction which has clear semantics and should be supported by every assembler that handles the OpenSSL Thumb2 code. (In other files, the ADR vs SUB conditionals are based on __thumb2__ already. For some reason, this one is based on __APPLE__, I'm guessing to deal with an older version of clang assembler.) It's unclear to me which of clang or binutils is "correct" or if this is even a well-defined notion beyond "whatever binutils does". But I will note that https://github.com/openssl/openssl/pull/4669 suggests binutils has also changed behavior around this before. Reviewed-by: NAndy Polyakov <appro@openssl.org> Reviewed-by: NRich Salz <rsalz@openssl.org> (Merged from https://github.com/openssl/openssl/pull/5431)
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