Hi all, this patch enables Branch Target Identification Armv8.1-M Mechanism [1]. This is achieved by using the bti pass made common with Aarch64. The pass iterates through the instructions and adds the necessary BTI instructions at the beginning of every function and at every landing pads targeted by indirect jumps. Best Regards Andrea [1] gcc/ChangeLog 2022-04-07 Andrea Corallo * config.gcc (arm*-*-*): Add 'aarch-bti-insert.o' object. * config/arm/arm-protos.h: Update. * config/arm/arm.cc (aarch_bti_enabled, aarch_bti_j_insn_p) (aarch_pac_insn_p, aarch_gen_bti_c, aarch_gen_bti_j): New functions. * config/arm/arm.md (bti_nop): New insn. * config/arm/t-arm (PASSES_EXTRA): Add 'arm-passes.def'. (aarch-bti-insert.o): New target. * config/arm/unspecs.md (UNSPEC_BTI_NOP): New unspec. * config/arm/aarch-bti-insert.cc (rest_of_insert_bti): Update to verify arch compatibility. * config/arm/arm-passes.def: New file. gcc/testsuite/ChangeLog 2022-04-07 Andrea Corallo * gcc.target/arm/bti-1.c: New testcase. * gcc.target/arm/bti-2.c: Likewise.