perf(evm): skip redundant initial Snapshot in OCC executor path

[pdrobnjak]

Summary

• Skip the redundant initial Snapshot() call in NewDBImpl for the OCC executor hot path
• Add NewDBImplWithoutSnapshot() used only by executeEVMTxWithGigaExecutor
• Original NewDBImpl preserved for all other callers (tests, RPC, ante handlers)

Problem

In the OCC executor path, each EVM transaction creates 3 CacheMultiStore layers:

prepareTask:   CMS1 (VIS-wrapped)       ← needed for OCC isolation
NewDBImpl:     CMS2 (wrapping CMS1)     ← REDUNDANT
Prepare:       CMS3 (wrapping CMS2)     ← needed for EVM revert support

CMS2 exists to provide a GetCommittedState baseline via snapshottedCtxs[0]. But no state changes occur between NewDBImpl and Prepare (called by go-ethereum's StateTransition.Execute), so Prepare's Snapshot provides the same baseline.

Profiling after #2808 (30s, M4 Max, 1000 EVM transfers/block):

Metric	Value
DBImpl.Snapshot alloc_space (cum)	44.8 GB
cachemulti.newStoreWithoutGiga alloc_space	22.5 GB
CMS layers per tx	3 (only 2 needed)

Changes

• giga/deps/xevm/state/statedb.go: Add NewDBImplWithoutSnapshot() constructor + defensive guard on flushEvents
• giga/deps/xevm/state/state.go: Defensive guard on GetCommittedState for empty snapshottedCtxs
• app/app.go: Hot path uses NewDBImplWithoutSnapshot

Benchmark Results (M4 Max, 1000 EVM transfers/block, 30s profile)

Metric	Before (after #2808)	After	Delta
TPS (steady-state range)	7,800–9,000	7,200–8,600	median ~8,000
DBImpl.Snapshot alloc_space	44.8 GB cum	19.5 GB cum	-9.8 GB flat
cachemulti.newStoreWithoutGiga alloc	22.5 GB	12.0 GB	-10.5 GB
newCacheMultiStoreFromCMS alloc (cum)	38.8 GB	14.2 GB cum	-17.9 GB cum
Total alloc_space	457 GB	313 GB	-144 GB (-31%)
Idle CPU (usleep+kevent+pthread_cond_wait)	42.9s	30.1s	-30% idle
memclrNoHeapPointers CPU	2.1s	10.7s	+8.6s (more fresh spans)

Note: TPS is flat despite -31% alloc because freed CPU shifts from idle to allocation overhead (memclrNoHeapPointers). Workers complete faster but the GC/allocator remains the bottleneck.

pprof -alloc_space -diff_base highlights

 -9,840 MB  DBImpl.Snapshot              (direct savings — one fewer CMS per tx)
-10,482 MB  cachemulti.newStoreWithoutGiga (cascading)
 -5,807 MB  btree.NewFreeListG            (cascading)
 -6,992 MB  sync.newIndirectNode          (cascading)
 -4,622 MB  sync.newEntryNode             (cascading)
 -4,194 MB  sei-db utils.Clone            (cascading)

pprof -top -diff_base highlights (CPU)

 +8.60s  runtime.memclrNoHeapPointers  (more fresh spans allocated)
 -8.07s  runtime.usleep                (less idle — workers busier)
 -2.51s  runtime.kevent                (less idle)
 -2.22s  runtime.pthread_cond_wait     (less contention)
 +2.50s  runtime.heapBitsSmallForAddr  (more heap metadata tracking)

Why safe

• In the OCC path, core.ApplyMessage → StateTransition.Execute always calls Prepare() → Snapshot() before any EVM state reads/writes
• GetCommittedState uses snapshottedCtxs[0] which is set by Prepare's Snapshot() — same committed state baseline
• All other NewDBImpl callers (tests, RPC, ante) keep the initial Snapshot() for isolation
• Defensive guards prevent panics if snapshottedCtxs is empty

Test plan

• go test ./giga/deps/xevm/state/... -count=1 — pass (including TestSnapshot)
• go test ./giga/tests/... -count=1 — pass (all 14 giga tests)
• gofmt -s -w clean
• Benchmark 2000+ blocks with heap profiling

🤖 Generated with Claude Code

[github-actions]

The latest Buf updates on your PR. Results from workflow Buf / buf (pull_request).

Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Feb 11, 2026, 1:20 PM

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.78%. Comparing base (f1c3021) to head (08c4efe).
⚠️ Report is 6 commits behind head on perf/lazy-cachemultistore.

Files with missing lines	Patch %	Lines
giga/deps/xevm/state/state.go	0.00%	1 Missing and 1 partial ⚠️
giga/deps/xevm/state/statedb.go	84.61%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@                      Coverage Diff                      @@
##           perf/lazy-cachemultistore    #2819      +/-   ##
=============================================================
+ Coverage                      56.77%   56.78%   +0.01%     
=============================================================
  Files                           2070     2070              
  Lines                         168336   168351      +15     
=============================================================
+ Hits                           95572    95600      +28     
+ Misses                         64280    64259      -21     
- Partials                        8484     8492       +8     

Flag	Coverage Δ
sei-chain	40.89% <75.00%> (+0.01%)	⬆️
sei-cosmos	48.17% <ø> (+<0.01%)	⬆️
sei-db	68.72% <ø> (ø)
sei-tendermint	58.68% <ø> (-0.04%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
app/app.go	65.88% <100.00%> (+0.07%)	⬆️
giga/deps/xevm/state/state.go	95.12% <0.00%> (-1.58%)	⬇️
giga/deps/xevm/state/statedb.go	43.82% <84.61%> (+3.55%)	⬆️

... and 32 files with indirect coverage changes

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[pdrobnjak]

This PR was auto-merged by GitHub during a stack reorder (branch force-push made head appear merged into base). No code was actually merged to main. This PR has been superseded — see the restacked PR chain starting at #2849.