Commit Graph

69 Commits (f3c6119cf63d21671bbad9bdfb983316b0336dd8)

Author SHA1 Message Date
Paul Mackerras e30a87593a decode: Start moving towards decoding by major opcode first
With this, we have a table for most major opcodes and separate
tables for each major opcode that has further decoding required.
These tables are still mostly indexed by the ppc_insn_t values,
however.

A few things are still decoded completely at the top level: nop,
attn and sim_config.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
Paul Mackerras c9e92483b8 decode: Push mtspr/mfspr register decoding down into execute1
Instead of doing mfctr, mflr, mftb, mtctr, mtlr as separate ops,
just pass down mfspr and mtspr ops with the spr number and let
execute1 decode which SPR we're addressing.  This will help reduce
the number of instruction bits decode1 needs to look at.

In fact we now pass down the whole instruction from decode2 to
execute1.  We will need more bits of the instruction in future,
and the tools should just optimize away any that we don't end
up using.  Since the 'aa' bit was just a copy of an instruction
bit, we can now remove it from the record.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
Benjamin Herrenschmidt 3e6f656a90 Add MCRF instruction
Hopefully it's not too timing catastrophic. The variable newcrf will
be handy for the other CR ops when we implement them I suspect.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
5 years ago
Benjamin Herrenschmidt 554ae88540 Implement absolute branches
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
5 years ago
Anton Blanchard b57325ce29 Merge branch 'divider' of https://github.com/paulusmack/microwatt 5 years ago
Anton Blanchard 5a6f8d26d1 Rename OP_SUBFC -> OP_SUBFE, OP_ADDC -> OP_ADDE
These were somewhat badly named.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
5 years ago
Paul Mackerras d5bc6c8824 Add a divider unit and a testbench for it
This adds a divider unit, connected to the core in much the same way
that the multiplier unit is connected.  The division algorithm is
very simple-minded, taking 64 clock cycles for any division (even
32-bit division instructions).

The decoding is simplified by making use of regularities in the
instruction encoding for div* and mod* instructions.  Instead of
having PPC_* encodings from the first-stage decoder for each of the
different div* and mod* instructions, we now just have PPC_DIV and
PPC_MOD, and the inputs to the divider that indicate what sort of
division operation to do are derived from instruction word bits.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
5 years ago
Benjamin Herrenschmidt 98f0994698 Add core debug module
This module adds some simple core controls:

  reset, stop, start, step

along with icache clear and reading the NIA and core
status bits

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org
5 years ago
Anton Blanchard 7bb88d5321
Merge pull request #59 from antonblanchard/trap-decode
Fix make check
5 years ago
Anton Blanchard 427effdaa9 Fix make check
We need to finish support for all the trap instructions, but for now
we at least need a decode entry for tw, so we know to stall until the
previous instruction completes. Some of our test cases were failing
because the trap executed before the previous instruction completed.

All these trap instructions need to be resolved at completion, not
in execute.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
5 years ago
Anton Blanchard 9867fb6149 Add a decode for the nop instruction
We want these to go out without any GPR dependencies, so add
a specific entry in decode for them.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
5 years ago
Anton Blanchard acdb2ea157 No need to gate nia or insn in decode1
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
5 years ago
Anton Blanchard b9e28598b4 Explicitly check against '1' in if statements
nvc doesn't like what I think is a VHDL 2008 construct. Lets just
check against '1' explicitly.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
5 years ago
Anton Blanchard a2df2a10a2 Remove sim console
We can force all existing code to use the UART console
by passing 0 in bit zero of the sim config register.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
5 years ago
Anton Blanchard 92a7152370 Rework pipeline, add stall and flush signals
This adds stall and flush signals to the pipeline.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
5 years ago
Anton Blanchard 9687034d78 Add a decode bit to mark an instruction as single through the pipeline
This is used by the pipelining patches. Mark everyone as single through
the pipeline to start.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
5 years ago
Benjamin Herrenschmidt b0ade2857f decode1 array fix header
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
5 years ago
Anton Blanchard 9fbaea6f08 Rework CR file and add forwarding
Handle the CR as a single field with per nibble enables. Forward any
writes in the same cycle.

If this proves to be an issue for timing, we may want to revisit
this in the future. For now, it keeps things simple.

Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
5 years ago
Anton Blanchard 5a29cb4699 Initial import of microwatt
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
5 years ago