* ctrl: copy dispatch2 to avoid cross-module loops

This commit makes copies of dispatch2 in CtrlBlock to avoid long
cross-module timing loop paths. Should be good for timing.

* dpq: re-write queue read logic

This commit adds a Reg-Vec to store the queue read data. Since
most queues read at most the current numRead and the next numRead
entries, the read timing can be optimized by reading the data one
cycle earlier.

* 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

* feat: parameterize load/store pipeline, etc.

* fix: use LoadPipelineWidth rather than LoadQueueSize

* fix: parameterize `rdataPtrExtNext`

* SBuffer: fix idx update logic

* atomic: parameterize atomic logic in `MemBlock`

* StoreQueue: update allow enque requirement

* feat: support one load/store pipeline

* feat: parameterize `EnsbufferWidth`

* chore: resharp codes for better generated name

CSRs are updated later after instructions commit from ROB. Thus, we
need to delay difftest commit for several cycles.

This commit adds an LsqEnqCtrl module to add one more clock cycle
between dispatch and load/store queue.

LsqEnqCtrl maintains the lqEnqPtr/sqEnqPtr and lqCounter/sqCounter.
They are used to determine whether load/store queue can accept new
instructions. After that, instructions are sent to load/store queue.
This module decouples queue allocation and real enqueue.

Besides, uop storage in load/store queue are optimized. In dispatch,
only robIdx is required. Other information is naturally conveyed in
the pipeline and can be stored later in load/store queue if needed.
For example, exception vector, trigger, ftqIdx, pdest, etc are
unnecessary before the instruction leaves the load/store pipeline.

This commit optimizes the coding style and timing for hardware
performance counters.

By default, performance counters are RegNext(RegNext(_)).

This commit adds WritebackSink and WritebackSource parameters for
multiple modules. These traits hide implementation details from
other modules by defining IO-related functions in modules.

By using WritebackSink, ROB is able to choose the writeback sources.
Now fflags and exceptions are connected from exe units to reduce write
ports and optimize timing.

Further optimizations on write-back to RS and better coding style to
be added later.

* FDivSqrt: use hierarchy API to avoid dedup bug

* Dedup: use hartId from io port instead of core parameters

* Bump fudian

* difftest: add basic difftest features for releases

This commit adds basic difftest features for every release, no matter
it's for simulation or physical design. The macro SYNTHESIS is used to
skip these logics when synthesizing the design. This commit aims at
allowing designs for physical design to be verified.

* bump ready-to-run

* difftest: add int and fp writeback data

* disable log as default
* code clean up

This commit changes when instructions enter load/store queue.
Now, at dispatch2, load/store instructions enter load/store queue.

* Add perf counters
* add reg from hpm counter source
* add print perfcounter enable

Previously difftest uses the extra 32 read ports of regfile and it is
disabled by default under FPGAPlatform. However, when FPGAPlatform is
enabled, we also drop the right 32 read ports and it causes errors.

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

This commit adds IOs for performance counters in reservation stations.
Only `full` is included for now.

* 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

This commit adds fpStateReadOut and fpStateReadIn ports to Scheduler to
support reading fp reg states from other schedulers.

It should have better timing because now ExuBlock(0) has only int
regfile and busytable. This block does not need fp writeback any more.

This commit moves load/store reservation stations into the first
ExuBlock (or calling it IntegerBlock). The unnecessary dispatch module
is also removed from CtrlBlock.

Now the module organization becomes:
* ExuBlock: Int RS, Load/Store RS, Int RF, Int FUs
* ExuBlock_1: Fp RS, Fp RF, Fp FUs
* MemBlock: Load/Store FUs

Besides, load queue has 80 entries and store queue has 64 entries now.

* change ROB to 256 entries
* change physical register file to 192 entries
* re-organize reservation stations, function units and regfile

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 load balance strategy in issue selection logic for
reservation stations.

Previously we have a load balance option in ExuBlock, but it cannot work
if the function units have feedbacks to RS. In this commit it is
removed.

This commit adds a victim index option for oldestFirst. For LOAD, the
first issue port has better performance and thus we set the victim index
to 0. For other function units, we use the last issue port.

This commit adds manual reset for every register in Regfile. Previously
the reset is done by add reset values to the registers. However,
physically general-purpose register file does not have reset values.

Since all the regfile always has the same writeback data, we don't need
to explicitly assign reset data.

This PR adds support for fast load-to-load wakeup and issue. In load-to-load fast wakeup and issue, load-to-load latency is reduced to 2 cycles.

Now a load instruction can wakeup another load instruction at LOAD stage 1. When the producer load instruction arrives at stage 2, the consumer load instruction is issued to load stage 0 and using data from the producer to generate load address.

In reservation station, load can be dequeued from staged 1 when stage 2 does not have a valid instruction. If the fast load is not accepted, from the next cycle on, the load will dequeue as normal.

Timing in reservation station (for imm read) and load unit (for writeback data selection) to be optimized later.

* backend,rs: issue load one cycle earlier when possible

This commit adds support for issuing load instructions one cycle
earlier if the load instruction is wakeup by another load. An extra
2-bit UInt is added to IO.

* mem: add load to load addr fastpath framework

* mem: enable load to load forward

* mem: add load-load forward counter
Co-authored-by: NWilliam Wang <zeweiwang@outlook.com>

* 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>

This commit limits dequeue width of every RS to 2 for better timing.

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. 

Backend --> ExuBlock --> FuBlock --> Exu --> Function Units
        -->          --> Scheduler --> RS

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

XiangShan is jointly released by ICT and PCL.

* change the number of function units in MinimalConfig
* remove some hard-wired values

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.

* change the number of function units in MinimalConfig
* remove some hard-wired values

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.