MONDAY, AUGUST 10, 2026
gas — Proposed
gas: Fix support for AL condition in Thumb-2 IT instruction
Patch allows unconditional instructions within IT AL blocks in GAS for Thumb-2, fixing incorrect rejection.
This patch addresses an issue in GAS where unconditional instructions following an IT AL (Always) instruction in Thumb-2 were incorrectly rejected. The change allows these unconditional instructions, as they are designed to not affect flags and can be encoded as 16-bit instructions. It also adds error handling for illegal Else conditions within IT AL blocks.
In the Thread
- proposer
Proposes a change to allow unconditional instructions within IT AL blocks in GAS for Thumb-2.
“Using the AL condition in the IT instruction is designed to allow encoding unconditional 16-bit instructions which do not affect flags. GAS currently allows specifying the AL condition, but rejects any following unconditional instructions because they are not considered to be part of an IT block. This change makes unconditional instructions allowed inside a manually-specified IT AL block. Note,…”
- reviewer
Approves of the patch but requests additional comments for clarity.
“It generally looks good, but I'd like to request you to add a few comments, see below:”