4 ms·
Little addendum: Macro-op fusion (alone) does not only reduce the number of uop, it could also reduces physical register usage as intermediate results are not
by avianes 4y ago
Little addendum:
Macro-op fusion (alone) does not only reduce the number of uop, it could also reduces physical register usage as intermediate results are not stored into physical registers.
For instance, the indexed load pattern (ADD+LOAD) without macro-op fusion needs:
- 2 physical registers in read;
- 2 physical registers in write (one per macro-op), meaning that 2 physical registers will be allocated.
While the macro-op fused version needs:
- 2 physical registers in read;
- 1 physical register in write, meaning that a single physical register will be allocated.