Exception address is used serveral cycles after flush. We delay it
by more cycles to ensure its flush safety.

* IPrefetch: fix prefetchPtr stop problem

* This problem happens because prefetchPtr still exits when close IPrefetch

* Fix PMP req port still be occupied even when ICache miss

* Shut down IPrefetch

* IPrefetch: fix Hint not set PreferCache bit

* bump HuanCun

* mem: optimize missq reject to lq timing

DCache replay request is quite slow to generate, as it need to compare
load address with address in all valid miss queue entries.

Now we delay the usage of replay request from data cache.
Now replay request will not influence normal execution flow until
load_s3 (1 cycle after load_s2, load result writeback to RS).

Note1: It is worth mentioning that "select refilling inst for load
writeback" will be disabled if dcacheRequireReplay in the
last cycle.

Note2: ld-ld violation or forward failure will let an normal load inst replay
from fetch. If TLB hit and ld-ld violation / forward failure happens,
we write back that inst immediately. Meanwhile, such insts will not be
replayed from rs.

* dcache: compare probe block addr instead of full addr

* difftest: bump difftest to support --no-diff test

* ci: add cacheoptest test (--no-diff)

* dcache: use sram to build ecc array

* MainPipe: latch s1_encTag to last until s1_fire
Authored-by: Nzhanglinjuan <zhanglinjuan20s@ict.ac.cn>

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 removed PriorityEncoder in sbuffer enq path. It should improve sbuffer enqueue timing.

* pma: allow r/w priv for l3-cache op mmio space

* bump huancun

* bump huancun

* bump huancun

* Add Naive Instruction Prefetch

* Add instruction prefetch module in ICache

* send Hint to L2 (prefetched data stores in L2)

* Ftq: add prefetchPtr and prefetch interface

* Fix IPrefetch PMP Port preempting problem

* Fix merge conflict

Refactor Trigger

* ICache: raise access fault when L2 send corrupt

* ICache: add ECC error connection

* chores: add comments and code clean-up

* ICache: raise AF when Meta/Data Parity wrong

* Update Frontend.scala

* dcache: let ecc error and l2 corrupt raise load af

If CSR.smblockctl.cache_error_enable is disabled, ecc error and l2 corrupt
will not raise any exception.

* mem: enable cache error by default

* mem: support store ecc check, add ecc error csr

Support store / atom ecc check (early version)
Add ecc error csr to distingush ecc error and other access fault

Timing opt and unit tests to be added.

* memblock: regnext ptw's resp

* pmp: timing optimization from tlb.sram.ppn to pmp, add static pmp check

long latency: tlb's sram may be slow to gen ppn, ppn to pmp may be
long latency.
Solution: add static pmp check.

Fatal problem: pmp grain is smalled than TLB pages(4KB, 2MB, 1GB)
Solution: increase pmp'grain to 4K, for 4K entries, pre-check pmp and
store the result into tlb storage. For super pages, still dynamic check
that translation and check.

* pmp: change pmp grain to 4KB, change pma relative init config

* bump ready-to-run, update nemu so for pmp grain

* bump ready-to-run, update nemu so for pmp grain again

  update pmp unit test. The old test assumes that pmp grain is less than 512bit.

* Change L3 to 6MB

* Bump huancun

We have singlestep already so triggers do not need to hit after inst commits

* dcache: fix bug in ecc check

* dcache: remove redundant ecc array

* CacheInstruction: fix typo

* dcache: fix bugs in cache instruction on ecc

* MetaArray: wrap ecc array as a single module

* fix invalidTakenFault use wrong seqTarget

* IFU: fix oversize bug

* ctrl: mark all flushes as level.flush for frontend

This commit changes how flushes behave for frontend.

When ROB commits an instruction with a flush, we notify the frontend
of the flush without the commit.

Flushes to frontend may be delayed by some cycles and commit before
flush causes errors. Thus, we make all flush reasons to behave the
same as exceptions for frontend, that is, RedirectLevel.flush.

* IFU: exclude lastTaken situation when judging beyond fetch
Co-authored-by: NYinan Xu <xuyinan@ict.ac.cn>

* Debug Mode: support basic difftest with spike

* Debug Mode: fix some bugs

Bugs fixed are:
1. All interrupts and exceptions cause debug mode to enter park loop
2. Debug interrupt ignored due to flushPipe

* mmpma: fix read/write io decoupled logic

* pma: fix init pma config

This commit adds fused load support by bypassing LUI results to load.

For better timing, detection is done at the rename stage. Imm is stored
in psrc(1), psrc(0) and imm.

This commit optimizes Dispatch2Rs timing by ignoring lsq.canAccept
when sending bits to reservation stations.

* ICache: add ReplacePipe for Probe & Release

* remove ProbeUnit

* Probe & Release enter ReplacePipe

* fix bugs when running Linux on MinimalConfig

* TODO: set conflict for ReplacePipe

* ICache: fix ReplacePipe invalid write bug

* chores: code clean up

* IFU: optimize timing

* PreDecode: separate into 2 module for timing optimization

* IBuffer: add enqEnable to replace valid for timing

* IFU/ITLB: optimize timing

* IFU: calculate cut_ptr in f1

* TLB: send req in f1 and wait resp in f2

* ICacheMainPipe: add tlb miss logic in s0

* Optimize IFU timing

* IFU: fix lastHalfRVI bug

* IFU: fix performance bug

* IFU: optimize MMIO commit timing

* IFU: optmize trigger timing and add frontendTrigger

* fix compile error

* IFU: fix mmio stuck bug

This commit changes the condition to update mtval and stval.

According to the RISC-V spec, when a trap is taken into M/S-mode,
mtval/stval is either set to zero or written wrih exception-specific
information to assist software in handling the trap.

Previously in XiangShan, mtval/stval is updated depending on the
current priviledge mode, which is incorrect.

* MissQueue: loose merging condition to ease timing stress

* MissQueue: remove grant_beats

* MissQueue: compare block addr, not the whole addr bits

* dcache: optimize timing for generating ready to sbuffer
Co-authored-by: NWilliam Wang <zeweiwang@outlook.com>