[PATCH v2 2/3] aarch64: warn if the TME feature is used during assembly.
Alice Carlotti
alice.carlotti@arm.com
Fri Jun 26 15:54:28 GMT 2026
On Fri, Jun 26, 2026 at 02:35:15PM +0100, Richard Earnshaw wrote:
> Arm has obsoleted the unimplemented TME feature. Warn if instructions
> from this feature are encountered.
We could only use these instruction in assembly if we specify the +tme
extension, and if we're deprecating the instructions then we should deprecate
the flag as well. So I think it would be better to emit the deprecation
warning when parsing the "+tme" extension (and we need only warn about this
once).
Alice
>
> Also tweak warn_unpredictable_ldst to use const more often, since the
> arguments are the same as for the new warn_deprecated function.
> ---
> gas/NEWS | 4 ++++
> gas/config/tc-aarch64.c | 24 ++++++++++++++++++++++--
> gas/testsuite/gas/aarch64/tme-warn.l | 15 +++++++++++++++
> gas/testsuite/gas/aarch64/tme.d | 1 +
> include/opcode/aarch64.h | 6 ++++--
> opcodes/aarch64-tbl.h | 10 +++++-----
> 6 files changed, 51 insertions(+), 9 deletions(-)
> create mode 100644 gas/testsuite/gas/aarch64/tme-warn.l
>
> diff --git a/gas/NEWS b/gas/NEWS
> index 4c55a544f25..116d5e62be6 100644
> --- a/gas/NEWS
> +++ b/gas/NEWS
> @@ -1,5 +1,9 @@
> -*- text -*-
>
> +* The aarch64 TME extension has never been implemented in any products. Arm
> + has withdrawn it from the architecture. The assembler will now warn if
> + instructions from the extension are detected during assembly.
> +
> * The legacy .vtable_entry and .vtable_inherit directives that were
> needed for versions of GCC prior to gcc-3.0 (when the generic C++
> ABI was adopted) are now considered obsolete. They are now deprecated
> diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
> index 9632a5b2a01..587c3588b09 100644
> --- a/gas/config/tc-aarch64.c
> +++ b/gas/config/tc-aarch64.c
> @@ -8743,9 +8743,9 @@ programmer_friendly_fixup (aarch64_instruction *instr)
> /* Check for loads and stores that will cause unpredictable behavior. */
>
> static void
> -warn_unpredictable_ldst (aarch64_instruction *instr, char *str)
> +warn_unpredictable_ldst (const aarch64_instruction *instr, const char *str)
> {
> - aarch64_inst *base = &instr->base;
> + const aarch64_inst *base = &instr->base;
> const aarch64_opcode *opcode = base->opcode;
> const aarch64_opnd_info *opnds = base->operands;
> switch (opcode->iclass)
> @@ -8841,6 +8841,25 @@ warn_unpredictable_ldst (aarch64_instruction *instr, char *str)
> }
> }
>
> +static void
> +warn_deprecated (const aarch64_instruction *instr, const char *str)
> +{
> + const aarch64_inst *base = &instr->base;
> + const aarch64_opcode *opcode = base->opcode;
> + if (!(opcode->flags & F_DEPRECATED_INSN))
> + return;
> + switch (opcode->iclass)
> + {
> + case tme:
> + as_warn (_("the TME feature has been deprecated -- `%s'"), str);
> + break;
> + default:
> + /* Instruction marked as deprecated, but a suitable warning not
> + added above. */
> + abort();
> + }
> +}
> +
> static void
> force_automatic_sequence_close (void)
> {
> @@ -9019,6 +9038,7 @@ md_assemble (char *str)
> }
>
> warn_unpredictable_ldst (&inst, str);
> + warn_deprecated (&inst, str);
>
> if (inst.reloc.type == BFD_RELOC_UNUSED
> || !inst.reloc.need_libopcodes_p)
> diff --git a/gas/testsuite/gas/aarch64/tme-warn.l b/gas/testsuite/gas/aarch64/tme-warn.l
> new file mode 100644
> index 00000000000..ed26e4ed95c
> --- /dev/null
> +++ b/gas/testsuite/gas/aarch64/tme-warn.l
> @@ -0,0 +1,15 @@
> +[^:]*: Assembler messages:
> +.*: Warning: the TME feature has been deprecated -- `tstart x0'
> +.*: Warning: the TME feature has been deprecated -- `tstart X0'
> +.*: Warning: the TME feature has been deprecated -- `tstart x15'
> +.*: Warning: the TME feature has been deprecated -- `tstart X15'
> +.*: Warning: the TME feature has been deprecated -- `tstart x30'
> +.*: Warning: the TME feature has been deprecated -- `tstart X30'
> +.*: Warning: the TME feature has been deprecated -- `tcommit'
> +.*: Warning: the TME feature has been deprecated -- `tcommit'
> +.*: Warning: the TME feature has been deprecated -- `ttest x0'
> +.*: Warning: the TME feature has been deprecated -- `ttest X30'
> +.*: Warning: the TME feature has been deprecated -- `tcancel 0'
> +.*: Warning: the TME feature has been deprecated -- `tcancel 65535'
> +.*: Warning: the TME feature has been deprecated -- `tcancel 0xffff'
> +.*: Warning: the TME feature has been deprecated -- `tcancel 0XA'
> diff --git a/gas/testsuite/gas/aarch64/tme.d b/gas/testsuite/gas/aarch64/tme.d
> index 24d34ea9561..66527b03921 100644
> --- a/gas/testsuite/gas/aarch64/tme.d
> +++ b/gas/testsuite/gas/aarch64/tme.d
> @@ -1,4 +1,5 @@
> #as: -march=armv8-a+tme
> +#warning_output: tme-warn.l
> #objdump: -dr
>
> .* file format .*
> diff --git a/include/opcode/aarch64.h b/include/opcode/aarch64.h
> index f51045210c9..2d8514b8e7d 100644
> --- a/include/opcode/aarch64.h
> +++ b/include/opcode/aarch64.h
> @@ -1219,6 +1219,7 @@ enum aarch64_insn_class
> sve_shift_tsz_bhsd,
> sve_size_tsz_bhs,
> testbranch,
> + tme,
> cryptosm3,
> cryptosm4,
> dotproduct,
> @@ -1479,7 +1480,8 @@ extern const aarch64_opcode aarch64_opcode_table[];
> #define F_OD(X) (((X) & 0x7) << 24)
> /* Instruction has the field of 'sz'. */
> #define F_LSE_SZ (1 << 27)
> -
> +/* The instruction has been deprecated. */
> +#define F_DEPRECATED_INSN (1 << 28)
>
> #define F_SYS_READ (1ULL << 29)
> /* This system instruction is used to write system registers. */
> @@ -1542,7 +1544,7 @@ extern const aarch64_opcode aarch64_opcode_table[];
> /* As above, plus PN registers. */
> #define F_INVALID_IMM_SYMS_3 (3ULL << 42)
>
> -/* Next bit is 44, and 28 is also unused. */
> +/* Next bit is 44. */
>
> /* Instruction constraints. */
> /* This instruction has a predication constraint on the instruction at PC+4. */
> diff --git a/opcodes/aarch64-tbl.h b/opcodes/aarch64-tbl.h
> index 518109ecfd6..c6cb5257008 100644
> --- a/opcodes/aarch64-tbl.h
> +++ b/opcodes/aarch64-tbl.h
> @@ -3374,7 +3374,7 @@ static const aarch64_feature_set aarch64_feature_mpamv2 =
> #define MEMTAG_INSN(NAME,OPCODE,MASK,CLASS,OPS,QUALS,FLAGS) \
> { NAME, OPCODE, MASK, CLASS, 0, MEMTAG, OPS, QUALS, FLAGS | F_INVALID_IMM_SYMS_1, 0, 0, NULL }
> #define _TME_INSN(NAME,OPCODE,MASK,CLASS,OP,OPS,QUALS,FLAGS) \
> - { NAME, OPCODE, MASK, CLASS, OP, TME, OPS, QUALS, FLAGS | F_INVALID_IMM_SYMS_1, 0, 0, NULL }
> + { NAME, OPCODE, MASK, CLASS, OP, TME, OPS, QUALS, FLAGS | F_INVALID_IMM_SYMS_1 | F_DEPRECATED_INSN, 0, 0, NULL }
> #define SVE2_INSN(NAME,OPCODE,MASK,CLASS,OP,OPS,QUALS,FLAGS,TIED) \
> { NAME, OPCODE, MASK, CLASS, OP, SVE2, OPS, QUALS, \
> FLAGS | F_INVALID_IMM_SYMS_2, 0, TIED, NULL }
> @@ -5154,10 +5154,10 @@ const struct aarch64_opcode aarch64_opcode_table[] =
> CORE_INSN ("adr", 0x10000000, 0x9f000000, pcreladdr, 0, OP2 (Rd, ADDR_PCREL21), QL_ADRP, 0),
> CORE_INSN ("adrp", 0x90000000, 0x9f000000, pcreladdr, 0, OP2 (Rd, ADDR_ADRP), QL_ADRP, 0),
> /* TME Instructions. */
> - _TME_INSN ("tstart", 0xd5233060, 0xffffffe0, 0, 0, OP1 (Rd), QL_I1X, 0),
> - _TME_INSN ("tcommit", 0xd503307f, 0xffffffff, 0, 0, OP0 (), QL_0, 0),
> - _TME_INSN ("ttest", 0xd5233160, 0xffffffe0, 0, 0, OP1 (Rd), QL_I1X, 0),
> - _TME_INSN ("tcancel", 0xd4600000, 0xffe0001f, 0, 0, OP1 (TME_UIMM16), QL_IMM_NIL, 0),
> + _TME_INSN ("tstart", 0xd5233060, 0xffffffe0, tme, 0, OP1 (Rd), QL_I1X, 0),
> + _TME_INSN ("tcommit", 0xd503307f, 0xffffffff, tme, 0, OP0 (), QL_0, 0),
> + _TME_INSN ("ttest", 0xd5233160, 0xffffffe0, tme, 0, OP1 (Rd), QL_I1X, 0),
> + _TME_INSN ("tcancel", 0xd4600000, 0xffe0001f, tme, 0, OP1 (TME_UIMM16), QL_IMM_NIL, 0),
> /* SME instructions (aliases for MSR <sysreg> operations. */
> SME_INSN ("smstart", 0xd503477f, 0xffffffff, sme_start, 0, OP0 (), QL_0, F_SYS_WRITE, 0),
> SME_INSN ("smstop", 0xd503467f, 0xffffffff, sme_stop, 0, OP0 (), QL_0, F_SYS_WRITE, 0),
> --
> 2.43.0
>
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