Also, assume that a target that is not taken should be removed from the
Btb. (The read that checked isn't possible with BRAM timing unless we
latched and had an extra port, but removing the check actually improved
performance a bit in CoreMark, and the pipeline should actually only be
reporting a non-taken branch if we did something wrong.)
The mode and well-formedness checks above also set fault to True, so we
end up with cases where a DataStore request uses the default load page
fault exception code. Instead, unconditionally set excStorePageFault for
DataStore, and conditionally override to excStoreCapPageFault when
appropriate, being particularly careful to ensure earlier exception
causes still take precedence.
Also restructure the InstFetch and DataLoad cases to match how DataStore
needs to look.
This fixes the rv64si-p-dirty ISA test, currently the sole failure.
Store the upper bits of the PC in a table and only handle indices and
lsbs in the main pipeline.
This eliminates redundancy between PCs and predicted PCs, and even more
between fragments of instructions.
Raise a store page fault if the PTE is missing R or W, even if the store is a
cap store and the PTE is also missing CW, as per the sail spec.
Co-authored-by: Jessica Clarke <jrtc27@jrtc27.com>
(Previously we ran into the limit of ports on the regFiles holding state
in the BTB. This uses a vector of regFiles with a vector of interfaces,
which is logically the same but might produce multiple copies of state.)
This means FetchStage should now behave in the same way with RVFI-DII as
with an I-Cache. A Dii_Parcel_Id is fed alongside PC everywhere relevant
and follows very similar logic, but, importantly it's just extra state
on the side, it doesn't affect what we do with the branch predictor and
parcel combining/instruction decoding logic.
BSC does not play nicely with enums whose labels do not start at 0 and
increase linearly. Instead, in such cases, it generates a whole bunch of
conditions to "legalise" any read values, which causes an explosion of
logic in places like the ROB. Thus, use this ugly (but still typed)
alternative that, other than naming conventions enforced by BSC, looks
almost the same as an enum.
