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* aarch64: Add the SME2 predicate-related instructionsRichard Sandiford2023-03-3037-845/+3961
| | | | | | | | | | | | | | | | | Implementation-wise, the main things to note here are: - the WHILE* instructions have forms that return a pair of predicate registers. This is the first time that we've had lists of predicate registers, and they wrap around after register 15 rather than after register 31. - the predicate-as-counter WHILE* instructions have a fourth operand that specifies the vector length. We can treat this as an enumeration, except that immediate values aren't allowed. - PEXT takes an unsuffixed predicate index of the form PN<n>[<imm>]. This is the first instance of a vector/predicate index having no suffix.
* aarch64: Add the SME2 multivector LD1 and ST1 instructionsRichard Sandiford2023-03-3040-448/+8895
| | | | | | | | | | | | | | | SME2 adds LD1 and ST1 variants for lists of 2 and 4 registers. The registers can be consecutive or strided. In the strided case, 2-register lists have a stride of 8, starting at register x0xxx. 4-register lists have a stride of 4, starting at register x00xx. The instructions are predicated on a predicate-as-counter register in the range pn8-pn15. Although we already had register fields with upper bounds of 7 and 15, this is the first plain register operand to have a nonzero lower bound. The patch uses the operand-specific data field to record the minimum value, rather than having separate inserters and extractors for each lower bound. This in turn required adding an extra bit to the field.
* aarch64: Add the SME2 MOVA instructionsRichard Sandiford2023-03-3021-314/+2282
| | | | | | | | | | | | | | SME2 defines new MOVA instructions for moving multiple registers to and from ZA. As with SME, the instructions are also available through MOV aliases. One notable feature of these instructions (and many other SME2 instructions) is that some register lists must start at a multiple of the list's size. The patch uses the general error "start register out of range" when this constraint isn't met, rather than an error specifically about multiples. This ensures that the error is consistent between these simple consecutive lists and later strided lists, for which the requirements aren't a simple multiple.
* aarch64: Add support for predicate-as-counter registersRichard Sandiford2023-03-3022-1600/+1983
| | | | | | | | | | | | SME2 adds a new format for the existing SVE predicate registers: predicates as counters rather than predicates as masks. In assembly code, operands that interpret predicates as counters are written pn<N> rather than p<N>. This patch adds support for these registers and extends some existing instructions to support them. Since the new forms are just a programmer convenience, there's no need to make them more restrictive than the earlier predicate-as-mask forms.
* aarch64; Add support for vector offset rangesRichard Sandiford2023-03-3013-13/+151
| | | | | | | | | | | Some SME2 instructions operate on a range of consecutive ZA vectors. This is indicated by syntax such as: za[<Wv>, <imml>:<immh>] Like with the earlier vgx2 and vgx4 support, we get better error messages if the parser allows all ZA indices to have a range. We can then reject invalid cases during constraint checking.
* aarch64: Add support for vgx2 and vgx4Richard Sandiford2023-03-3015-9/+173
| | | | | | | | | | | | | | | | | | | | | | | Many SME2 instructions operate on groups of 2 or 4 ZA vectors. This is indicated by adding a "vgx2" or "vgx4" group size to the ZA index. The group size is optional in assembly but preferred for disassembly. There is not a binary distinction between mnemonics that have group sizes and mnemonics that don't, nor between mnemonics that take vgx2 and mnemonics that take vgx4. We therefore get better error messages if we allow any ZA index to have a group size during parsing, and wait until constraint checking to reject invalid sizes. A quirk of the way errors are reported means that if an instruction is wrong both in its qualifiers and its use of a group size, we'll print suggested alternative instructions that also have an incorrect group size. But that's a general property that also applies to things like out-of-range immediates. It's also not obviously the wrong thing to do. We need to be relatively confident that we're looking at the right opcode before reporting detailed operand-specific errors, so doing qualifier checking first seems resonable.
* aarch64: Add _off4 suffix to AARCH64_OPND_SME_ZA_arrayRichard Sandiford2023-03-305-11/+11
| | | | | | | SME2 adds various new fields that are similar to AARCH64_OPND_SME_ZA_array, but are distinguished by the size of their offset fields. This patch adds _off4 to the name of the field that we already have.
* aarch64: Add a _10 suffix to FLD_imm3Richard Sandiford2023-03-306-8/+8
| | | | | SME2 adds various new 3-bit immediate fields, so this patch adds an lsb position suffix to the name of the field that we already have.
* aarch64: Add +sme2Richard Sandiford2023-03-304-0/+7
| | | | | This patch adds bare-bones support for +sme2. Later patches fill in the rest.
* aarch64: Prefer register ranges & support wrappingRichard Sandiford2023-03-3012-983/+1039
| | | | | | | | | | | | | Until now, binutils has supported register ranges such as { v0.4s - v3.4s } as an unofficial shorthand for { v0.4s, v1.4s, v2.4s, v3.4s }. The SME2 ISA embraces this form and makes it the preferred disassembly. It also embraces wrapped lists such as { z31.s - z2.s }, which is something that binutils didn't previously allow. The range form was already binutils's preferred disassembly for 3- and 4-register lists. This patch prefers it for 2-register lists too. The patch also adds support for wrap-around.
* aarch64: Add support for strided register listsRichard Sandiford2023-03-307-62/+135
| | | | | | | | | | | | | | | | | SME2 has instructions that accept strided register lists, such as { z0.s, z4.s, z8.s, z12.s }. The purpose of this patch is to extend binutils to support such lists. The parsing code already had (unused) support for strides of 2. The idea here is instead to accept all strides during parsing and reject invalid strides during constraint checking. The SME2 instructions that accept strided operands also have non-strided forms. The errors about invalid strides therefore take a bitmask of acceptable strides, which allows multiple possibilities to be summed up in a single message. I've tried to update all code that handles register lists.
* aarch64: Sort fields alphanumericallyRichard Sandiford2023-03-302-163/+164
| | | | | This patch just sorts the field enum alphanumerically, which makes it easier to see if a particular field has already been defined.
* aarch64: Resync field namesRichard Sandiford2023-03-301-7/+7
| | | | | This patch just makes the comments in aarch64-opc.c:fields match the names of the associated FLD_* enum.
* aarch64: Regularise FLD_* suffixesRichard Sandiford2023-03-306-55/+55
| | | | | | | | | | | Some FLD_imm* suffixes used a counting scheme such as FLD_immN, FLD_immN_2, FLD_immN_3, etc., while others used the lsb as the suffix. The latter seems more mnemonic, and was a big help in doing the SME2 work. Similarly, the _10 suffix on FLD_SME_size_10 was nonobvious. Presumably it indicated a 2-bit field, but it actually starts in bit 22.
* aarch64: Rename some of GAS's REG_TYPE_* macrosRichard Sandiford2023-03-301-71/+71
| | | | | | | | | | | | | In GAS, the vector and predicate registers are identified by REG_TYPE_VN, REG_TYPE_ZN and REG_TYPE_PN. This "N" is obviously a placeholder for the register number. However, we don't use that convention for integer and FP registers, and (more importantly) SME2 adds "predicate-as-counter" registers that are denoted PN. This patch therefore drops the "N" suffix from the existing registers. The main hitch is that Z was also used for the zero register in things like R_Z, but using ZR seems more consistent with the SP-based names.
* aarch64: Add a aarch64_cpu_supports_inst_p helperRichard Sandiford2023-03-303-2/+17
| | | | | | | | | | | | | | Quite a lot of SME2 instructions have an opcode bit that selects between 32-bit and 64-bit forms of an instruction, with the 32-bit forms being part of base SME2 and with the 64-bit forms being part of an optional extension. It's nevertheless useful to have a single opcode entry for both forms since (a) that matches the ISA definition and (b) it tends to improve error reporting. This patch therefore adds a libopcodes function called aarch64_cpu_supports_inst_p that tests whether the target supports a particular instruction. In future it will depend on internal libopcodes routines.
* aarch64: Reorder some OP_SVE_* macrosRichard Sandiford2023-03-301-16/+16
| | | | This patch just moves some out-of-order-looking OP_SVE_* macros.
* aarch64: Rename aarch64-tbl.h OP_SME_* macrosRichard Sandiford2023-03-301-81/+77
| | | | | | | | This patch renames the OP_SME_* macros in aarch64-tbl.h so that they follow the same scheme as the OP_SVE_* ones. It also uses OP_SVE_ as the prefix, since there is no real distinction between the SVE and SME uses of qualifiers: a macro defined for one can be useful for the other too.
* aarch64: Tweak priorities of parsing-related errorsRichard Sandiford2023-03-302-11/+51
| | | | | | | | | | | | | | | | | | | There are three main kinds of error reported during parsing, in increasing order of priority: - AARCH64_OPDE_RECOVERABLE (register seen instead of immediate) - AARCH64_OPDE_SYNTAX_ERROR - AARCH64_OPDE_FATAL_SYNTAX_ERROR This priority makes sense when comparing errors reported against the same operand. But if we get to operand 3 (say) and see a register instead of an immediate, that's likely to be a better match than something that fails with a syntax error at operand 1. The idea of this patch is to prioritise parsing-related errors based on operand index first, then by error code. Post-parsing errors still win over parsing errors, and their relative priorities don't change.
* aarch64: Try to report invalid variants against the closest matchRichard Sandiford2023-03-307-112/+131
| | | | | | | | | | | | | If an instruction has invalid qualifiers, GAS would report the error against the final opcode entry that got to the qualifier- checking stage. It seems better to report the error against the opcode entry that had the closest match, just like we pick the closest match within an opcode entry for the "did you mean this?" message. This patch adds the number of invalid operands as an argument to AARCH64_OPDE_INVALID_VARIANT and then picks the AARCH64_OPDE_INVALID_VARIANT with the lowest argument.
* aarch64: Tweak register list errorsRichard Sandiford2023-03-304-20/+18
| | | | | | | | | | | | | | | The error for invalid register lists had the form: invalid number of registers in the list; N registers are expected at operand M -- `insn' This seems a bit verbose. Also, the "bracketing" is really: (invalid number of registers in the list; N registers are expected) at operand M but the semicolon works against that. This patch goes for slightly shorter messages, setting a template that later patches can use for more complex cases.
* aarch64: Make AARCH64_OPDE_REG_LIST take a bitfieldRichard Sandiford2023-03-302-21/+35
| | | | | | | | | | | | | | | | | AARCH64_OPDE_REG_LIST took a single operand that specified the expected number of registers. However, there are quite a few SME2 instructions that have both 2-register forms and (separate) 4-register forms. If the user tries to use a 3-register list, it isn't obvious which opcode entry they meant. Saying that we expect 2 registers and saying that we expect 4 registers would both be wrong. This patch therefore switches the operand to a bitfield. If a AARCH64_OPDE_REG_LIST is reported against multiple opcode entries, the patch ORs up the expected lengths. This has no user-visible effect yet. A later patch adds more error strings, alongside tests that use them.
* aarch64: Add an operand class for SVE register listsRichard Sandiford2023-03-305-27/+27
| | | | | | | | | | | | SVE register lists were classified as SVE_REG, since there had been no particular reason to separate them out. However, some SME2 instructions have tied register list operands, and so we need to distinguish registers and register lists when checking whether two operands match. Also, the register list operands used a general error message, even though we already have a dedicated error code for register lists that are the wrong length.
* aarch64: Commonise checks for index operandsRichard Sandiford2023-03-301-18/+32
| | | | | This patch splits out the constraint checking for index operands, so that it can be reused by new SME2 operands.
* aarch64: Add an error code for out-of-range registersRichard Sandiford2023-03-303-7/+31
| | | | | | | | libopcodes currently reports out-of-range registers as a general AARCH64_OPDE_OTHER_ERROR. However, this means that each register range needs its own hard-coded string, which is a bit cumbersome if the range is determined programmatically. This patch therefore adds a dedicated error type for out-of-range errors.
* aarch64: Deprioritise AARCH64_OPDE_REG_LISTRichard Sandiford2023-03-302-8/+12
| | | | | | | | | | | | | | | | | | SME2 has many instructions that take a list of SVE registers. There are often multiple forms, with different forms taking different numbers of registers. This means that if, after a successful parse and qualifier match, we find that the number of registers does not match the opcode entry, the associated error should have a lower priority/severity than other errors reported at the same stage. For example, if there are 2-register and 4-register forms of an instruction, and if the assembly code uses the 2-register form with an out-of-range value, the out-of-range value error against the 2-register instruction should have a higher priority than the "wrong number of registers" error against the 4-register instruction. This is tested by the main SME2 patches, but seemed worth splitting out.
* aarch64: Update operand_mismatch_kind_namesRichard Sandiford2023-03-302-1/+6
| | | | | The contents of operand_mismatch_kind_names were out of sync with the enum.
* aarch64: Rework reporting of failed register checksRichard Sandiford2023-03-3023-972/+1202
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are many opcode table entries that share the same mnemonic. Trying to parse an invalid assembly line will trigger an error for each of these entries, but the specific error might vary from one entry to another, depending on the exact nature of the problem. GAS has quite an elaborate system for picking the most appropriate error out of all the failed matches. And in many cases it works well. However, one of the limitations is that the error is always reported against a single opcode table entry. If that table entry isn't the one that the user intended to use, then the error can end up being overly specific. This is particularly true if an instruction has a typoed register name, or uses a type of register that is not accepted by any opcode table entry. For example, one of the expected error matches for an attempted SVE2 instruction is: Error: operand 1 must be a SIMD scalar register -- `addp z32\.s,p0/m,z32\.s,z0\.s' even though the hypothetical user was presumably attempting to use the SVE form of ADDP rather than the Advanced SIMD one. There are many other instances of this in the testsuite. The problem becomes especially acute with SME2, since many SME2 instructions reuse existing mnemonics. This could lead to us reporting an SME-related error against a non-SME instruction, or a non-SME-related error against an SME instruction. This patch tries to improve things by collecting together all the register types that an opcode table entry expected for a given operand. It also records what kind of register was actually seen, if any. It then tries to summarise all this in a more directed way, falling back to a generic error if the combination defies a neat summary. The patch includes tests for all new messages except REG_TYPE_ZA, which only triggers with SME2. To test this, I created an assembly file that contained the cross product of all known mnemonics and one example from each register class. I then looked for cases where the new routines fell back on the generic errors ("expected a register" or "unexpected register type"). I locally added dummy messages for each one until there were no more hits. The patch adds a specimen instruction to diagnostics.s for each of these combinations. In each case, the combination didn't seem like something that could be summarised in a natural way, so the generic messages seemed better. There's always going to be an element of personal taste around this kind of thing though. Adding more register types made 1<<REG_TYPE_MAX exceed the range of the type, but we don't actually need/want 1<<REG_TYPE_MAX.
* aarch64: Try to avoid inappropriate default errorsRichard Sandiford2023-03-306-5/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | After parsing a '{' and the first register, parse_typed_reg would report errors in subsequent registers in the same way as for the first register. It used set_default_error, which reports errors of the form "operand N must be X". The problem is that if there are multiple opcode entries for the same mnemonic, there could be several matches that lead to a default error. There's no guarantee that the default error for the register list is the one that will be chosen. To take an example from the testsuite: ext z0.b,{z31.b,z32.b},#0 gave: operand 2 must be an SVE vector register with the error being reported against the single-vector version of ext, even though the operand is clearly a list. This patch uses set_fatal_syntax_error to bump the priority of the error once we're sure that the operand is a list of the right type.
* aarch64: Improve errors for malformed register listsRichard Sandiford2023-03-306-21/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | parse_typed_reg is used for parsing both bare registers and registers that occur in lists. If it doesn't see a register, or sees an unexpected kind of register, it queues a default error to report the problem. These default errors have the form "operand N must be an X", where X comes from the operand table. If there are multiple opcode entries that report default errors, GAS tries to pick the most appropriate one, using the opcode table order as a tiebreaker. But this can lead to cases where a syntax error in a register list is reported against an opcode that doesn't accept register lists. For example, the unlikely error: ext z0.b,{,},#0 is reported as: operand 2 must be an SVE vector register -- `ext z0.b,{,},#0' even though operand 2 can be a register list. If we've parsed the opening '{' of a register list, and then see something that isn't remotely register-like, it seems better to report that directly as a syntax error, rather than rely on the default error. The operand won't be a valid list of anything, so there's no need to pick a specific Y in "operand N must be a list of Y".
* aarch64: Tweak parsing of integer & FP registersRichard Sandiford2023-03-301-29/+42
| | | | | | | | | | | | | | | Integer registers were parsed indirectly through aarch64_reg_parse_32_64 (and thus aarch64_addr_reg_parse) rather than directly through parse_reg. This was because we need the qualifier associated with the register, and the logic to calculate that was buried in aarch64_addr_reg_parse. The code that parses FP registers had the same need, but it open-coded the calculation of the qualifier. This patch tries to handle both cases in the same way. It is needed by a later patch that tries to improve the register-related diagnostics.
* aarch64: Tweak errors for base & offset registersRichard Sandiford2023-03-309-293/+308
| | | | | | | | | | | parse_address_main currently uses get_reg_expected_msg to report invalid base and offset registers, but the disadvantage of doing that is that it isn't immediately clear which register is wrong (the base or the offset). A later patch moves away from using get_reg_expected_msg for failed type checks, but doing that here didn't seem like the best approach. The patch tries to use more tailored messages instead.
* aarch64: Tweak error for missing immediate offsetRichard Sandiford2023-03-305-18/+18
| | | | | This patch tweaks the error message that is printed when a ZA-style index is missing the immediate offset.
* aarch64: Move w12-w15 range check to libopcodesRichard Sandiford2023-03-308-32/+51
| | | | | | | | | | | | | | | | | | | In SME, the vector select register had to be in the range w12-w15, so it made sense to enforce that during parsing. However, SME2 adds instructions for which the range is w8-w11 instead. This patch therefore moves the range check from the parsing stage to the constraint-checking stage. Also, the previous error used a capitalised range W12-W15, whereas other register range errors used lowercase ranges like p0-p7. A quick internal poll showed a preference for the lowercase form, so the patch uses that. The patch uses "selection register" rather than "vector select register" so that the terminology extends more naturally to PSEL.
* aarch64: Commonise index parsingRichard Sandiford2023-03-301-21/+21
| | | | | | Just a minor clean-up to factor out the index parsing, partly to ensure that the error handling remains consistent. No behavioural change intended.
* aarch64: Consolidate ZA slice parsingRichard Sandiford2023-03-305-72/+55
| | | | | | | | | | | | Now that parse_typed_reg checks the range of tile register numbers and libopcodes checks the range of vector select offsets, there's very little difference between the parsing of ZA tile indices, ZA array indices, and PSEL indices. The main one is that ZA array indices don't currently allow "za" to be qualified, but we need to remove that restriction for SME2. This patch therefore consolidates all three parsers into a single routine, parameterised by the type of register that they expect.
* aarch64: Move ZA range checks to aarch64-opc.cRichard Sandiford2023-03-3012-165/+145
| | | | | | | | | | | | | | | | | | | | | | | | | This patch moves the range checks on ZA vector select offsets from gas to libopcodes. Doing the checks there means that the error messages contain the expected range. It also fits in better with the error severity scheme, which becomes important later. (This is because out-of-range indices are treated as more severe than syntax errors, on the basis that parsing must have succeeded if we get to the point of checking the completed opcode.) The patch also adds a new check_za_access function for checking ZA accesses. That's a bit over the top for one offset check, but the function becomes more complex with later patches. sme-9-illegal.s checked for an invalid .q suffix using: psel p1, p15, p3.q[w15] but this is doubly invalid because it misses the immediate part of the index. The patch keeps that test but adds another with a zero index, so that .q is the only thing wrong. The aarch64-tbl.h change includes neatening up the backslash positions.
* aarch64: Pass aarch64_indexed_za to parsersRichard Sandiford2023-03-301-152/+78
| | | | | | | | | | ZA indices have more parts than most operands, so passing these parts around individually is more awkward than for other operand types. Things aren't too bad at the moment, but SME2 adds two further pieces: an offset range and a vector group size. This patch therefore replaces arguments for the individual pieces with a single argument for the index as a whole.
* aarch64: Make indexed_za use 64-bit immediatesRichard Sandiford2023-03-302-4/+4
| | | | | | | | | A later patch moves the range checking for ZA vector select offsets from gas to libopcodes. That in turn requires the immediate field to be big enough to support all parsed values. This shouldn't be a particularly size-sensitive structure, so there should be no memory problems with doing this.
* aarch64: Rename za_tile_vector to za_indexRichard Sandiford2023-03-305-55/+58
| | | | | | | | | za_tile_vector is also used for indexing ZA as a whole, rather than just for indexing tiles. The former is more common than the latter in SME2, so this patch generalises the name to "indexed_za". The patch also names the associated structure, so that later patches can reuse it during parsing.
* aarch64: Treat ZA as a registerRichard Sandiford2023-03-305-48/+91
| | | | | | | | | | | | | | | | | | | | | | | We already treat the ZA tiles ZA0-ZA15 as registers. This patch does the same for ZA itself. parse_sme_zero_mask can then parse ZA tiles and ZA in the same way, through parsed_type_reg. One important effect of going through parsed_type_reg (in general) is that it allows ZA to take qualifiers. This is necessary for many SME2 instructions. However, to support existing unqualified uses of ZA, parse_reg_with_qual needs to treat the qualiier as optional. Hopefully the net effect is to give better error messages, since now that SME2 makes "za.<T>" valid in some contexts, it might be natural to use it (incorrectly) in ZERO too. While there, the patch also tweaks the error messages for invalid ZA tiles, to try to make some cases more specific. For now, parse_sme_za_array just uses parse_reg, rather than parse_typed_reg/parse_reg_with_qual. A later patch consolidates the parsing further.
* aarch64: Consolidate ZA tile range checksRichard Sandiford2023-03-306-163/+127
| | | | | | | | Now that all parsing of ZA tile names goes through parse_typed_reg, we can check there for out-of-range tile numbers. The other check performed by parse_sme_zada_operand was to reject .q, but that can now be done via F_STRICT instead. (.q tiles are valid in other contexts, so they shouldn't be rejected in parse_typed_reg.)
* aarch64: Reuse parse_typed_reg for ZA tilesRichard Sandiford2023-03-301-51/+47
| | | | | | | This patch reuses the general parse_typed_reg for ZA tiles. This involves adding a way of suppressing the usual treatment of register indices, since ZA indices look very different from Advanced SIMD and SVE vector indices.
* aarch64: Rework parse_typed_reg interfaceRichard Sandiford2023-03-301-71/+53
| | | | | | | | | | | | parse_typed_reg returned a register number and passed the register type back using a pointer parameter. It seems simpler to return the register entry instead, since that has both pieces of information in one place. The patch also replaces the boolean in_reg_list parameter with a mask of flags. This hopefully makes calls easier to read (more self-documenting than "true" or "false"), but more importantly, it allows a later patch to add a second flag.
* aarch64: Move vectype_to_qualifier further upRichard Sandiford2023-03-301-75/+75
| | | | | | This patch just moves vectype_to_qualifier further up, so that a later patch can call it at an earlier point in the file. No behavioural change intended.
* aarch64: Add REG_TYPE_ZATHVRichard Sandiford2023-03-301-14/+9
| | | | | | This patch adds a multi-register type that includes both REG_TYPE_ZATH and REG_TYPE_ZATV. This slightly simplifies the existing code, but the main purpose is to enable later patches.
* aarch64: Rename REG_TYPE_ZA* to REG_TYPE_ZAT*Richard Sandiford2023-03-301-10/+11
| | | | | | | | The ZA tile registers were called REG_TYPE_ZA, REG_TYPE_ZAH and REG_TYPE_ZAV. However, a later patch wants to make plain "za" a register type too, and REG_TYPE_ZA is the obvious name for that. This patch therefore adds "T" (tile) to the existing names.
* aarch64: Use aarch64_operand_error more widelyRichard Sandiford2023-03-301-22/+8
| | | | | | | | GAS's aarch64_instruction had its own cut-down error record, but it's better for later patches if it reuses the binutils-wide aarch64_operand_error instead. The main difference is that aarch64_operand_error can store arguments to the error while aarch64_instruction couldn't.
* aarch64: Make SME instructions use F_STRICTRichard Sandiford2023-03-304-57/+64
| | | | | | | | | | This patch makes all SME instructions use F_STRICT, so that qualifiers have to be provided explicitly rather than being inferred from other operands. The main change is to move the qualifier setting from the operand-level decoders to the opcode level. This is one step towards consolidating the ZA parsing code and extending it to handle SME2.
* aarch64: Fix SVE2 register/immediate distinctionRichard Sandiford2023-03-303-1/+13
| | | | | | | | | | | | | | | | | | | | | | | | GAS refuses to interpret register names like x0 as unadorned immediates, due to the obvious potential for confusion with register operands. (An explicit #x0 is OK.) For compatibility reasons, we can't extend the set of registers that GAS rejects for existing instructions. For example: mov x0, z0 was valid code before SVE was added, so it needs to stay valid code even when SVE is enabled. But we can make GAS reject newer registers in newer instructions. The SVE instruction: and z0.s, z0.s, z0.h is therefore invalid, rather than z0.h being an immediate. This patch extends the SVE behaviour to SVE2. The old call to AARCH64_CPU_HAS_FEATURE was technically the wrong way around, although it didn't matter in practice for base SVE instructions since their avariants only set SVE.