In this commit, we add License for XiangShan project. 

* backend,RS: add numEnq parameter to allow multiple enqueue instructions

* backend,RS: support multiple issue instructions at each cycle

* 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

* PTW: add ptw multi-processing graph

* [WIP] PTW: try to add miss queue, failed for complexity and not very useful

* [WIP] PTW: rewrite ptw for multi req support

* PTW: remove some assert, fix level init bug

* PTW: itlb has highter priority than dtlb

* PTW: fix bug that mix cache's resp logic

* PTW: fix stupid bug that mix .U and .W

* PTW: replay will not be blocked if fsm empty

* PTW: miss queue req may return miss queue

In the before design, only miss queue req can go into
fsm, and would not be blocked.
Now, to simplify design, miss queue req are just the
same with new req, may blocked, going to fsm or miss queue.

* PTW: fix ptw filter iss valid bug

* PTW.fsm: fix bug that should not mem.req when sfenceLatch

* PTW: fix ptw sfenceLatch's bug

* PTW: add some perf counters

* PTW: fix bug in filter enq ptr logic

* PTW: fix bug of sfence in ptw

* test: add current branch to ci-test, tmp

* PTW: fix bug of cache's hit logic and fsm's pf

* PTW: fix bug of filter's enq and block* signal

* PTW: fix bug of filter's pteResp filter

* PTW: add some assert of filter's counter

* PTW: fix bug of filter's enq logic

* PTW: set PTWMSHRSIZE 16

* PTW: fix naive perf counter's bug

* PTW: set PTWMSHRSIZE 8

* PTW: set PTWMSHRSIZE 32

* Revert "PTW: set PTWMSHRSIZE 32"

This reverts commit fd3981ae8bbb015c6cd398c4db60486d39fc92ef.

* Revert "test: add current branch to ci-test, tmp"

This reverts commit 8a7a8a494d5c05789e05a385a9fc7791a8ffef2f.

* LoadQueue: send stFtqIdx via rollback request

* It will make it possible for setore set to update its SSIT

* StoreSet: setup store set update req

* StoreSet: add store set identifier table (SSIT)

* StoreSet: add last fetched store table (LFST)

* StoreSet: put SSIT into decode stage

* StoreSet: put LFST into dispatch1

* Future work: optimize timing

* RS: store rs now supports delayed issue

* StoreSet: add perf counter

* StoreSet: fix SSIT update logic

* StoreSet: delay LFST update input for 1 cycle

* StoreSet: fix LFST update logic

* StoreSet: fix LFST raddr width

* StoreSet: do not force store in ss issue in order

Classic store set requires store in the same store set issue in seq.
However, in current micro-architecture, such restrict will lead to
severe perf lost. We choose to disable it until we find another way
to fix it.

* StoreSet: support ooo store in the same store set

* StoreSet: fix store set merge logic

* StoreSet: check earlier store when read LFST

* If store-load pair is in the same dispatch bundle, loadWaitBit should
also be set for load

* StoreSet: increase default SSIT flush period

* StoreSet: fix LFST read logic

* Fix commit c0e541d1

* StoreSet: add StoreSetEnable parameter

* RSFeedback: add source type

* StoreQueue: split store addr and store data

* StoreQueue: update ls forward logic

* Now it supports splited addr and data

* Chore: force assign name for load/store unit

* RS: add rs'support for store a-d split

* StoreQueue: fix stlf logic

* StoreQueue: fix addr wb sq update logic

* AtomicsUnit: support splited a/d

* Parameters: disable store set by default

* WaitTable: wait table will not cause store delay

* WaitTable: recover default reset period to 2^17

* Fix dev-stad merge conflict

* StoreSet: enable storeset

* RS: disable store rs delay logic

CI perf shows that current delay logic will cause perf loss. Disable
unnecessary delay logic will help.

To be more specific, `io.readyVec` caused the problem. It will be
updated in future commits.

* RS: opt select logic with load delay (ldWait)

* StoreSet: disable 2-bit lwt
Co-authored-by: NZhangZifei <zhangzifei20z@ict.ac.cn>

In this commit, we add support for using DPI-C calls to replace
DCache, PTW and L1plusCache. L2Cache and L3 Cache are also allowed to
be ignored or bypassed. Configurations are controlled by useFakeDCache,
useFakePTW, useFakeL1plusCache, useFakeL2Cache and useFakeL3Cache.
However, some configurations may not work correctly.

* RSFeedback: add source type

* StoreQueue: split store addr and store data

* StoreQueue: update ls forward logic

* Now it supports splited addr and data

* Chore: force assign name for load/store unit

* RS: add rs'support for store a-d split

* StoreQueue: fix stlf logic

* StoreQueue: fix addr wb sq update logic

* AtomicsUnit: support splited a/d

* StoreQueue: add sbuffer enq condition assertion

Store data op (std) may still be invalid after store addr op's (sta)
commitment, so datavalid needs to be checked before commiting
store data to sbuffer

Note that at current commit a non-completed std op for a
commited store may exist. We should make sure that uop
will not be cancelled by a latter branch mispredict. More work
to be done!

* Roq: add std/sta split writeback logic

Now store will commit only if both sta & std have been writebacked
Co-authored-by: NZhangZifei <zhangzifei20z@ict.ac.cn>

In this commit, we add performance counters for dispatch and issue stages
to track the number of instructions dispatched and issued. Active regfile
read ports are counted as ready instruction source registers.

* difftest: use DPI-C to refactor difftest

In this commit, difftest is refactored with DPI-C calls.
There're a few reasons:
(1) From Verilator's manual, DPI-C calls should be more efficient than accessing from dut_ptr.
(2) DPI-C is cross-platform (Verilator, VCS, ...)
(3) difftest APIs are splited from emu.cpp to possibly support more backend platforms
(NEMU, Spike, ...)

The performance at this commit is quite slower than the original emu.
Performance issues will be fixed later.

* [WIP] SimTop: try to use 'XSTop' as soc

* CircularQueuePtr: ues F-bounded polymorphis instead implict helper

* Refactor parameters & Clean up code

* difftest: support basic difftest

* Support diffetst in new sim top

* Difftest; convert recode fmt to ieee754 when comparing fp regs

* Difftest: pass sign-ext pc to dpic functions && fix exception pc

* Debug: add int/exc inst wb to debug queue

* Difftest: pass sign-ext pc to dpic functions && fix exception pc

* Difftest: fix naive commit num limit
Co-authored-by: NYinan Xu <xuyinan1997@gmail.com>
Co-authored-by: NWilliam Wang <zeweiwang@outlook.com>

* csr: remove unused input perfcnt io

* perfcnt: add some in-core hardware performance counters

* perfcnt: optimize timing for hardware performance counters

just record the tlb result(access and miss) of first issue by add
signal isFirstIssue (isFirstIssue = cntCountQueue(i) === 0.U)

* LoadUnit: generate fastUop in load_s1

* RS/Load: add load to fast wakeup when cache hit, while maintain its slow

* RS: remove legacy assert that doesn't work for load has fast and slow

* LoadUnit: fix bug that fastUops's valid forgets load_s1.io.in.valid

* MemBlock: fix bug of loadUnit's fast and slow connect

IPC of coremark 10 cycles raise from 1.63 to 1.70

* RS: RegNext srcUpdate to use it at next cycle

* RS: add param EnableLoadFastWakeUp and set default to false
Co-authored-by: NWilliam Wang <zeweiwang@outlook.com>

* RS: add many rs's perf cnter

* RS: add param myName for submodule name

* RS: set Integer&Mem block's rs' srcLen to XLEN

* xscore: remove reg and logic in xscore top module

* XSCore: remove logic in top module

* Fp/Int block: fix write back bug
Co-authored-by: NYinan Xu <xuyinan1997@gmail.com>

* RS: optimize numExist signal

* RS: fix some typo

* RS: optimize deq logic for block-nonfeedback rs

* WaitTable: add waittable framework

* WaitTable: get replay info from RedirectGenerator

* StoreQueue: maintain issuePtr for load rs

* RS: add loadWait to rs (only for load Unit's rs)

* WaitTable: fix update logic

* StoreQueue: fix issuePtr update logic

* chore: set loadWaitBit in ibuffer

* StoreQueue: fix issuePtrExt update logic

Former logic does not work well with mmio logic

We may also make sure that issuePtrExt is not before cmtPtrExt

* WaitTable: write with priority

* StoreQueue: fix issuePtrExt update logic for mmio

* chore: fix typos

* CSR: add slvpredctrl

* slvpredctrl will control load violation predict micro architecture

* WaitTable: use xor folded pc to index waittable
Co-authored-by: NZhangZifei <1773908404@qq.com>

* RS: pass ExuConfigs instead of wake-up port number to rs

* RS: store's rs's base-src dont care fp wake-up

* Backend: fix some bugs related to exu write

* Roq: revert to perv verision

* Fix fp write back bugs

But this would not work(for syntax bug) until other modules change

1. divide into three block
2. change io port:
  broadcastUop -> fastUopsIn
  selectUop    -> fastUopOut
  extraPorts   -> slowPorts
  etc.
the cross sub block io is not wrapped, to it later