MONDAY, OCTOBER 5, 2026
s390 — Proposed
s390: Add .insn pseudo-mnemonics rxy_a/b/c
Add support for s390 RXY instruction variants using .insn.
This patch adds support for three variants of the RXY instruction format (rxy_a, rxy_b, rxy_c) to the s390 gas assembler via the ‘.insn’ pseudo-mnemonic. These variants were introduced in different IBM processor generations (z990, z10, z17). The changes include updates to opcode definitions and test cases.
In Details
This patch adds support for three variants of the RXY instruction format (rxy_a, rxy_b, rxy_c) to the s390 GNU Assembler (gas) using the '.insn' pseudo-mnemonic. It defines these formats in opcodes/s390-opc.c and provides corresponding test cases in gas/testsuite/gas/s390/zarch-operands.d/.s, noting their introduction on specific IBM z/Architecture processors.
For Context
- .insn
- A GNU assembler directive that allows embedding raw instruction bytes or defining pseudo-mnemonics for specific instruction formats.
- pseudo-mnemonic
- An assembly language construct that represents a machine instruction, potentially with operands that are not direct encodings of machine code but are processed by the assembler.
- RXY
- A specific instruction format in the s390 architecture, with variants introduced across different processor generations.
- z990, z10, z17
- IBM mainframe processor generations that introduced different versions of the RXY instruction format.