refactor(compiler): inline EVM CLZ lowering (drop runtime-fallback path) - #21
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refactor(compiler): inline EVM CLZ lowering (drop runtime-fallback path)#21abmcar wants to merge 2 commits into
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✅ Performance Check Passed (interpreter) Performance Benchmark Results (threshold: 25%)
Summary: 194 benchmarks, 0 regressions |
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✅ Performance Check Passed (multipass) Performance Benchmark Results (threshold: 25%)
Summary: 194 benchmarks, 0 regressions |
⚡ Performance Regression Check Results✅ Performance Check Passed (interpreter)Performance Benchmark Results (threshold: 25%)
Summary: 194 benchmarks, 0 regressions ✅ Performance Check Passed (multipass)Performance Benchmark Results (threshold: 25%)
Summary: 194 benchmarks, 0 regressions |
Replace pure runtime fallback (callRuntimeFor -> intx::clz) with inline chain-select pattern modeled on handleExp's computeExpByteSize lambda (evm_mir_compiler.cpp:2511-2562). Saves HostArgScratch + Uint256ReturnBuffer roundtrip per CLZ. Tag result with ValueRange::U64 so downstream narrow consumers (PR DTVMStack#493 EVMRangeAnalyzer) can fire across basic blocks. clz(0) handled via outer Select(IsZero, 256, ...) for spec fidelity per EIP-7939, plus a defense-in-depth Limb|1 guard mirroring handleExp. Test: multipass unittests 223/223 (all 4 evm.clz_* incl. clz_osaka with 9 vectors), multipass statetest fork_Cancun 2723/2723.
handleClz now inlines a 4-limb chain-select pattern in the multipass frontend (previous commit), so the GetClz runtime helper has no remaining callers. Drop the typedef field, declaration, dispatch table registration, and implementation.
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Superseded by upstream DTVMStack#516 (now includes dead-code cleanup as a second commit). |
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✅ Performance Check Passed (interpreter) Performance Benchmark Results (threshold: 25%)
Summary: 194 benchmarks, 0 regressions |
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✅ Performance Check Passed (multipass) Performance Benchmark Results (threshold: 25%)
Summary: 194 benchmarks, 0 regressions |
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Summary
Replace
handleClzruntime-fallback path with an inline 4-limb expansion:when the EVM
CLZopcode (EIP-7939) is executed, the JIT now emits achain of compares +
OP_clz(64-bit) + selects, then an outer guardSelect(IsZero(value), 256, partial)for the all-zero input case. Theinner limb is also OR-masked with
1so the 64-bitOP_clzoperandis never zero on any select arm.
Output
Operandis taggedValueRange::U64(CLZ result is always ≤ 256,trivially U64). This is consistent with
EVMRangeAnalyzer, which alreadyclassifies
OP_CLZas U64 in its dataflow transfer table — the MIR taghelps same-block consumers; cross-BB consumers continue to be served by
the analyzer.
What this does NOT do
RuntimeFunctions.GetClzandevmGetClz(src/compiler/evm_frontend/evm_imported.{h,cpp}) areno longer called from the JIT path but remain in the table as dead
surface. Cleanup deferred to a follow-up to keep this diff focused.
CLZ-density signal; this PR is correctness-and-cleanup, not perf.
Test plan
tools/format.sh check— passcmake --build build --target dtvmapi— pass, no new warningsevmone-unittestscurated 223/223 — includingevm.clz_gas,evm.clz_osaka,evm.clz_pre_osaka,evm.clz_stack_underflowevmone-statetest -k fork_Cancun2723/2723 (fork_Cancunfilter excludes osaka/ tests, so statetest does not exercise EIP-7939
directly — coverage comes from unittests)
DRAFT — personal fork integration test
Drafting on
abmcar/DTVM(personal fork) for review/integration testing.Not for
DTVMStack/DTVMupstream submission yet.