[PATCH 1/2] s390: Simplify (dis)assembly of insn operands with const bits

[Andreas Krebbel]

On 7/12/24 16:11, Jens Remus wrote:
> Simplify assembly and disassembly of extended mnemonics with operands
> with constant ORed bits:
> Their instruction template already contains the respective constant
> operand bits, as they are significant to distinguish the extended from
> their base mnemonic. Operands are ORed into the instruction template.
> Therefore it is not necessary to OR the constant bits into the operand
> value during assembly in s390_insert_operand.
> Additionally the constant operand bits from the instruction template
> can be used to mask them from the operand value during disassembly in
> s390_print_insn_with_opcode. For now do so for non-length unsigned
> integer operands only.
>
> The separate instruction formats need to be retained, as their masks
> differ, which is relevant during disassembly to distinguish the base
> and extended mnemonics from each other.
>
> This affects the following extended mnemonics:
> - vfaebs, vfaehs, vfaefs
> - vfaezb, vfaezh, vfaezf
> - vfaezbs, vfaezhs, vfaezfs
> - vstrcbs, vstrchs, vstrcfs
> - vstrczb, vstrczh, vstrczf
> - vstrczbs, vstrczhs, vstrczfs
> - wcefb, wcdgb
> - wcelfb, wcdlgb
> - wcfeb, wcgdb
> - wclfeb, wclgdb
> - wfisb, wfidb, wfixb
> - wledb, wflrd, wflrx
>
> include/
> 	* opcode/s390.h (S390_OPERAND_OR1, S390_OPERAND_OR2,
> 	S390_OPERAND_OR8): Remove.
>
> opcodes/
> 	* s390-opc.c (U4_OR1_24, U4_OR2_24, U4_OR8_28): Remove.
> 	(INSTR_VRR_VVV0U1, INSTR_VRR_VVV0U2, INSTR_VRR_VVV0U3): Define
> 	as INSTR_VRR_VVV0U0 while retaining respective insn fmt mask.
> 	(INSTR_VRR_VV0UU8): Define as INSTR_VRR_VV0UU while retaining
> 	respective insn fmt mask.
> 	(INSTR_VRR_VVVU0VB1, INSTR_VRR_VVVU0VB2, INSTR_VRR_VVVU0VB3):
> 	Define as INSTR_VRR_VVVU0VB while retaining respective insn fmt
> 	mask.
> 	* s390-dis.c (s390_print_insn_with_opcode): Mask constant
> 	operand bits set in insn template of non-length unsigned
> 	integer operands.
>
> gas/
> 	* config/tc-s390.c (s390_insert_operand): Do not OR constant
> 	operand value bits.

Indeed, the ORing seems to be redundant. Good catch!

Ok to apply. Thanks!


Andreas