[Patch] MIPS opcodes: fix transposed FS and FT in vadda and vmsuba
Project / Subsystem
binutils / binutils
Date
2026-07-25
Proposer
"Piotr P. Stefaniak" <pstef@freebsd.org>
Source type
public_inbox
Consensus
Proposed
Sentiment
—/10
Technical tradeoffs
- • Correcting the operand order fixes incorrect calculations but requires updating the opcode definitions.
- • Ensuring accurate instruction decoding is critical for disassemblers and emulators to correctly represent and process MIPS code.
All attributes
- project
- binutils
- subsystem
- binutils
- patch_id
- —
- discussion_id
- amTYLdrTAhjBPlZ3@freefall.freebsd.org
- source_type
- public_inbox
- title
- [Patch] MIPS opcodes: fix transposed FS and FT in vadda and vmsuba
- headline
- MIPS opcodes: fix transposed FS and FT in vadda and vmsuba
- tldr
- Fixes a bug in MIPS opcodes where the order of source operands FS and FT was transposed in vadda and vmsuba instructions.
- proposer
- "Piotr P. Stefaniak" <pstef@freebsd.org>
- consensus
- Proposed
- outcome
- proposed
- sentiment_score
- —
- technical_tradeoffs
-
- • Correcting the operand order fixes incorrect calculations but requires updating the opcode definitions.
- • Ensuring accurate instruction decoding is critical for disassemblers and emulators to correctly represent and process MIPS code.
- series_id
- —
- series_role
- standalone
- series_parts
- []
- tags
-
- • binutils
- • MIPS
- • disassembler
- • opcode
- • floating point
- bugzilla_url
- —
- date
- 2026-07-25T00:00:00.000Z
[Patch] MIPS opcodes: fix transposed FS and FT in vadda and vmsuba
A patch addresses a bug in the MIPS opcode definitions within opcodes/mips-opc.c where the source operands FS and FT were transposed in the vadda and vmsuba instructions. This transposition causes incorrect results in some cases because the PS2 multiplier is not symmetric and the order matters for the Booth recoder, leading to a one ULP difference.