v0.7.2-scalar

Decisions Taken:

• #58 Finalised the feature groups and moved them from working spreadsheet into the specification - Section 2.
• #64 Agreed on hint for instruction latency / constant time requirements - Section 3.6.
• #63 Removed register-register versions of grev,gorc,shfl,unshfl due to lack of use-case.

Changes:

• Section 3.1.2 now explicitly lists which pseudo-instructions and immediate values relating to grevi, gorci, shfli and unshfli are required, rather than appearing to require the whole instruction. This is a long overdue change reflecting common consensus at the meetings, but until now not codified in the specification.
• Moved constant-time requirements regarding clmul[h] into the new dedicated Section 3.6.
• #61, #62 More explanations around the Entropy Source section following meetings with BSI. These are non-functional changes.

Additions:

• A hint based on source register addresses to encode whether integer and carry-less multiply instructions must execute in constant time. Section 3.6.
• Details of the instruction feature sets. Section 2.

Removals:

• grev,gorc,shfl,unshfl due to lack of use-case. Specific immediate variants are still used. The instructions remain in the Bitmanip extension.

Open Issues:

See the status of the open issues in the project board. The most pressing issues for the scalar specification are:

• #16 Instruction Encodings.