* dp2: add a pipeline for load/store

Load/store Dispatch2 has a bad timing because it requires the fuType
to disguish the out ports. This brings timing issues because the
instruction has to read busyTable after the port arbitration.

This commit adds a pipeline in dp2Ls, which may cause performance
degradation. Instructions are dispatched according to out, and at
the next cycle it will leave dp2.

* bump difftest trying to fix vcs

This commit optimizes the issue grant timing when age is enabled.
Select from age and SelectPolicy are processed parallely.

* mdp: implement SSIT with sram

* mdp: use robIdx instead of sqIdx

Dispatch refactor moves lsq enq to dispatch2, as a result, mdp can not
get correct sqIdx in dispatch. Unlike robIdx, it is hard to maintain a
"speculatively assigned" sqIdx, as it is hard to track store insts in
dispatch queue. Yet we can still use "speculatively assigned" robIdx
for memory dependency predictor.

For now, memory dependency predictor uses "speculatively assigned"
robIdx to track inflight store.

However, sqIdx is still used to track those store which's addr is valid
but data it not valid. When load insts try to get forward data from
those store, load insts will get that store's sqIdx and wait in RS.
They will not waken until store data with that sqIdx is issued.

* mdp: add track robIdx recover logic

This commit removes flush IO for every module. Flush now re-uses
redirect ports to flush the instructions.

* storeset: fix waitForSqIdx generate logic

Now right waitForSqIdx will be generated for earlier store in the same
dispatch bundle.

* mdp: add strict wait mode

When loadWaitStrict && loadWaitBit, load will wait in rs until all
older store addr calculation are finished.

* chore: add storeset_load_strict_wait counter

* mem: update block load logic

Now load will be selected as soon as the store it depends on is ready,
which is predicted by Store Sets

* mem: opt block load logic

Load blocked by std invalid will wait for that std to issue
Load blocked by load violation wait for that sta to issue

* csr: add 2 extra storeset config bits

Following bits were added to slvpredctl:
- storeset_wait_store
- storeset_no_fast_wakeup

* storeset: fix waitForSqIdx generate logic

Now right waitForSqIdx will be generated for earlier store in the same
dispatch bundle

Make bank conflict feedback 1 cycle earlier

* rename Roq to Rob

* remove trailing whitespaces

* remove unused parameters

This commit splits FMA instructions into FMUL and FADD for execution.

When the first two operands are ready, an FMA instruction can be issued
and the intermediate result will be written back to RS after two cycles.
Since RS currently has DataArray to store the operands, we reuse it to
store the intermediate FMUL result.

When an FMA enters deq stage and leaves RS with only two operands, we
mark it as midState ready at this clock cycle T0.

If the instruction's third operand becomes ready at T0, it can be
selected at T1 and issued at T2, when FMUL is also finished. The
intermediate result will be sent to FADD instead of writing back to RS.
If the instruction's third operand becomes ready later, we have the data
in DataArray or at DataArray's write port. Thus, it's ok to set midState
ready at clock cycle T0.

The separation of FMA instructions will increase issue pressure since RS
needs to issue more times. However, it larges reduce FMA latency if many
FMA instructions are waiting for the third operand.

This commit adds critical_wakeup_*_* counters to indicate which function
units wake up the instructions in RS. Previously we have wait_for_src_*
counters but they cannot represent where the critical operand (the last
waiting operand) comes from.

We need these counters to optimize fast wakeup logic. If some
instructions critically depend on some other instructions, we can think
of how we can optimize the wakeup process.

Furthermore, this commit also adds a specific counter for FMAs that
wakeup other FMAs' third operand. This helps us to decide which strategy
is used for FMA fast issue.

This commit moves issue select logic in reservation stations to stage 0
from stage 1. It helps timing of stage 1, which load-to-load requires.

Now, reservation stations have the following stages:

* S0: enqueue and wakeup, select. Selection results are RegNext-ed.
* S1: data/uop read and data bypass. Bypassed results are RegNext-ed.
* S2: issue instructions to function units.

This commit simplifies status logic in reservations stations. Module
StatusArray is mostly rewritten.

The following optimizations are applied:

* Wakeup now has higher priority than enqueue. This reduces the length
of the critical path of ALU back-to-back wakeup.

* Don't compare fpWen/rfWen if the reservation station does not have
float/int operands.

* Ignore status.valid or redirect for srcState update. For data capture,
these are necessary and not changed.

* Remove blocked and scheduled conditions in issue logic when the
reservation station does not have loadWait bit and feedback.

* Refactor print control transform

* Adda tilelink bus pmu

* Add performance counters for dispatch, issue, execute stages

* Add more counters in bus pmu

* Insert BusPMU between L3 and L2

* add some TMA perfcnt
Co-authored-by: NLinJiawei <linjiawei20s@ict.ac.cn>
Co-authored-by: NWilliam Wang <zeweiwang@outlook.com>
Co-authored-by: Nwangkaifan <wangkaifan@ict.ac.cn>

* backend, rs: add an age matrix to find the oldest instruction

This commit adds an age matrix to reservation station to find
the oldest instruction. This enables the RS to schedule the oldest
instruction first.

This commit also adda performance counter for oldest inst

This commit separates store address and store data in backend, including both reservation stations and function units. This commit also changes how stIssuePtr is updated. stIssuePtr should only be updated when both store data and address issue. 

This commit adds support for multiple enqueue for load and store RS.
Also update the parameters in XSCore to avoid explicitly setting wakeup ports.

Compare SqPtr when an instruction with wait bit enqueuing. This should have minor
performance improvements. Also add some performance counters.

XiangShan is jointly released by ICT and PCL.

This commit adds support for a parameterized scheduler. A scheduler
can be parameterized via issue and dispatch ports.

Note: other parameters have not been tested.

This commit adds an non-parameterized scheduler containing all reservation stations.
Now IntegerBlock, FloatBlock, MemBlock contain only function units.
The Schduler connects dispatch with all function units.
Parameterization to be added later.

This commit adds support for a parameterized scheduler. A scheduler
can be parameterized via issue and dispatch ports.

Note: other parameters have not been tested.

This commit adds an non-parameterized scheduler containing all reservation stations.
Now IntegerBlock, FloatBlock, MemBlock contain only function units.
The Schduler connects dispatch with all function units.
Parameterization to be added later.

In this commit, we add License for XiangShan project. 

* test,vcs: call $finish when difftest fails

* backend,RS: refactor with more submodules

This commit rewrites the reservation station in a more configurable style.

The new RS has not finished.
- Support only integer instructions
- Feedback from load/store instructions is not supported
- Fast wakeup for multi-cycle instructions is not supported
- Submodules are refined later

* RS: use wakeup signals from arbiter.out

* RS: support feedback and re-schedule when needed

For load and store reservation stations, the instructions that left RS before may be
replayed later.

* test,vcs: check difftest_state and return on nemu trap instructions

* backend,RS: support floating-point operands and delayed regfile read for store RS

This commit adds support for floating-point instructions in reservation stations.
Beside, currently fp data for store operands come a cycle later than int data. This
feature is also supported.

Currently the RS should be ready for any circumstances.

* rs,status: don't trigger assertions when !status.valid

* test,vcs: add +workload option to specify the ram init file

* backend,rs: don't enqueue when redirect.valid or flush.valid

* backend,rs: support wait bit that instruction waits until store issues

This commit adds support for wait bit, which is mainly used in load and
store reservation stations to delay instruction issue until the corresponding
store instruction issued.

* backend,RS: optimize timing

This commit optimizes BypassNetwork and PayloadArray timing.

- duplicate bypass mask to avoid too many FO4
- use one-hot vec to get read data