Commit Graph

9 Commits (813e2317bf1f1c10d988f660c0a4282da316a3b9)

Author SHA1 Message Date
Paul Mackerras 2491aa7fc5 core: Make popcnt* take two cycles
This moves the calculation of the result for popcnt* into the
countbits unit, renamed from countzero, so that we can take two cycles
to get the result.  The motivation for this is that the popcnt*
calculation was showing up as a critical path.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
2 years ago
Paul Mackerras a68921edca core: Fix mcrxrx, addpcis and bpermd
- mcrxrx put the bits in the wrong order

- addpcis was setting CR0 if the instruction bit 0 = 1, which it
  shouldn't

- bpermd was producing 0 always and additionally had the wrong bit
  numbering

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
2 years ago
Paul Mackerras 658feabfd4 core: Make result multiplexing explicit
This adds an explicit multiplexer feeding v.e.write_data in execute1,
with the select lines determined in the previous cycle based on the
insn_type.  Similarly, for multiply and divide instructions, there is
now an explicit multiplexer.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
3 years ago
Paul Mackerras 83816cb9e3 core: Implement BCD Assist instructions addg6s, cdtbcd, cbcdtod
To avoid adding too much logic, this moves the adder used by OP_ADD
out of the case statement in execute1.vhdl so that the result can
be used by OP_ADDG6S as well.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
4 years ago
Paul Mackerras b739372f7e core: Implement the bpermd instruction
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
4 years ago
Paul Mackerras 9b40b5a77b logical: Only do output inversion for OP_AND, OP_OR and OP_XOR
It's not needed for the other ops (popcnt, parity, etc.) and the
logical unit shows up as a critical path from time to time.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
4 years ago
Paul Mackerras ec2fa61792 execute1: Reduce width of the result mux to help timing
This reduces the number of different things that are assigned to
the result variable.

- The computations for the popcnt, prty, cmpb and exts instruction
  families are moved into the logical unit.
- The result of mfspr from the slow SPRs is computed in 'spr_val'
  before being assigned to 'result'.
- Writes to LR as a result of a blr or bclr instruction are done
  through the exc_write path to writeback.

This eases timing considerably.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
4 years ago
Paul Mackerras 0c714f1be6 execute: Move popcnt and prty instructions into the logical unit
This implements logic in the logical entity to calculate the results
of the popcnt* and prty* instructions.  We now have one insn_type_t
value for the 3 popcnt variants and one for the two prty variants,
using the length field of the decode_rom_t to distinguish between
them.  The implementations in logical.vhdl using recursive
algorithms rather than the simple functions in ppc_fx_insns.vhdl.

This gives a saving of about 140 slice LUTs on the A7-100 and
improves timing slightly.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
4 years ago
Anton Blanchard b8fb721b81 Consolidate logical instructions
Consolidate and/andc/nand, or/orc/nor and xor/eqv, using a common
invert on the input and output. This saves us about 200 LUTs.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
4 years ago