EIP-7939: added CLZ opcode for Osaka

circle.yml

@@ -470,13 +470,13 @@ jobs:
           working_directory: ~/build
           command: >
             bin/evmone-statetest ~/spec-tests/fixtures/state_tests/
-            --gtest_filter='-cancun/eip4844_blobs/blob_txs.invalid_tx_blob_count:frontier/precompiles/precompiles.precompiles:osaka/eip7594_peerdas/max_blob_per_tx.invalid_max_blobs_per_tx:osaka/eip7825_transaction_gas_limit_cap/tx_gas_limit.transaction_gas_limit_cap:osaka/eip7939_count_leading_zeros/*.*:osaka/eip7951_p256verify_precompiles/*.*:prague/eip7702_set_code_tx/set_code_txs.set_code_to_precompile'
+            --gtest_filter='-cancun/eip4844_blobs/blob_txs.invalid_tx_blob_count:frontier/precompiles/precompiles.precompiles:osaka/eip7594_peerdas/max_blob_per_tx.invalid_max_blobs_per_tx:osaka/eip7825_transaction_gas_limit_cap/tx_gas_limit.transaction_gas_limit_cap:osaka/eip7951_p256verify_precompiles/*.*:prague/eip7702_set_code_tx/set_code_txs.set_code_to_precompile'
       - run:
           name: "Fusaka pre-release execution spec tests (blockchain_tests)"
           working_directory: ~/build
           command: >
             bin/evmone-blockchaintest ~/spec-tests/fixtures/blockchain_tests/
-            --gtest_filter='-cancun/eip4844_blobs/blob_txs.valid_blob_tx_combinations:frontier/precompiles/precompiles.precompiles:osaka/eip7594_peerdas/max_blob_per_tx.max_blobs_per_tx_fork_transition:osaka/eip7825_transaction_gas_limit_cap/tx_gas_limit.transaction_gas_limit_cap_at_transition:osaka/eip7918_blob_reserve_price/*.*:osaka/eip7934_block_rlp_limit/max_block_rlp_size.block_at_rlp_size_limit_boundary:osaka/eip7939_count_leading_zeros/*.*:osaka/eip7951_p256verify_precompiles/*.*:prague/eip7702_set_code_tx/set_code_txs.set_code_to_precompile'
+            --gtest_filter='-cancun/eip4844_blobs/blob_txs.valid_blob_tx_combinations:frontier/precompiles/precompiles.precompiles:osaka/eip7594_peerdas/max_blob_per_tx.max_blobs_per_tx_fork_transition:osaka/eip7825_transaction_gas_limit_cap/tx_gas_limit.transaction_gas_limit_cap_at_transition:osaka/eip7918_blob_reserve_price/*.*:osaka/eip7934_block_rlp_limit/max_block_rlp_size.block_at_rlp_size_limit_boundary:osaka/eip7951_p256verify_precompiles/*.*:prague/eip7702_set_code_tx/set_code_txs.set_code_to_precompile'
       - collect_coverage_clang
       - upload_coverage:
           flags: eest-fusaka

lib/evmone/instructions.hpp

@@ -352,6 +352,11 @@ inline void sar(StackTop stack) noexcept
     x = (x >> y) | (sign_mask << mask_shift);
 }
 
+inline void clz(StackTop stack) noexcept
+{
+    stack.top() = clz(stack.top());
+}
+
 inline Result keccak256(StackTop stack, int64_t gas_left, ExecutionState& state) noexcept
 {
     const auto& index = stack.pop();

lib/evmone/instructions_opcodes.hpp

@@ -41,6 +41,7 @@ enum Opcode : uint8_t
     OP_SHL = 0x1b,
     OP_SHR = 0x1c,
     OP_SAR = 0x1d,
+    OP_CLZ = 0x1e,
 
     OP_KECCAK256 = 0x20,
 

lib/evmone/instructions_traits.hpp

@@ -173,6 +173,7 @@ constexpr inline GasCostTable gas_costs = []() noexcept {
     table[EVMC_PRAGUE] = table[EVMC_CANCUN];
 
     table[EVMC_OSAKA] = table[EVMC_PRAGUE];
+    table[EVMC_OSAKA][OP_CLZ] = 5;
 
     table[EVMC_EXPERIMENTAL] = table[EVMC_OSAKA];
 
@@ -281,6 +282,7 @@ constexpr inline std::array<Traits, 256> traits = []() noexcept {
     table[OP_SHL] = {"SHL", 0, false, 2, -1, EVMC_CONSTANTINOPLE, REV_EOF1};
     table[OP_SHR] = {"SHR", 0, false, 2, -1, EVMC_CONSTANTINOPLE, REV_EOF1};
     table[OP_SAR] = {"SAR", 0, false, 2, -1, EVMC_CONSTANTINOPLE, REV_EOF1};
+    table[OP_CLZ] = {"CLZ", 0, false, 1, 0, EVMC_OSAKA, REV_EOF1};
 
     table[OP_KECCAK256] = {"KECCAK256", 0, false, 2, -1, EVMC_FRONTIER, REV_EOF1};
 

lib/evmone/instructions_xmacro.hpp

@@ -63,7 +63,7 @@
     ON_OPCODE_IDENTIFIER(OP_SHL, shl)                         \
     ON_OPCODE_IDENTIFIER(OP_SHR, shr)                         \
     ON_OPCODE_IDENTIFIER(OP_SAR, sar)                         \
-    ON_OPCODE_UNDEFINED(0x1e)                                 \
+    ON_OPCODE_IDENTIFIER(OP_CLZ, clz)                         \
     ON_OPCODE_UNDEFINED(0x1f)                                 \
                                                               \
     ON_OPCODE_IDENTIFIER(OP_KECCAK256, keccak256)             \

test/unittests/CMakeLists.txt

@@ -29,6 +29,7 @@ target_sources(
     evm_eip3860_initcode_test.cpp
     evm_eip4844_blobhash_test.cpp
     evm_eip7516_blobbasefee_test.cpp
+    evm_eip7939_clz_test.cpp
     evm_eof_test.cpp
     evm_eof_calls_test.cpp
     evm_eof_function_test.cpp

test/unittests/evm_eip7939_clz_test.cpp

@@ -0,0 +1,56 @@
+// evmone: Fast Ethereum Virtual Machine implementation
+// Copyright 2025 The evmone Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+/// This file contains EVM unit tests for EIP-7939 "Count leading zeros (CLZ) opcode"
+/// https://eips.ethereum.org/EIPS/eip-7939
+
+#include "evm_fixture.hpp"
+
+using namespace evmc::literals;
+using namespace evmone::test;
+
+TEST_P(evm, clz_pre_osaka)
+{
+    rev = EVMC_PRAGUE;
+    const auto code = bytecode{OP_CLZ};
+
+    execute(code);
+    EXPECT_STATUS(EVMC_UNDEFINED_INSTRUCTION);
+}
+
+TEST_P(evm, clz_gas)
+{
+    rev = EVMC_OSAKA;
+    execute(bytecode{} + OP_PUSH0 + OP_CLZ);
+    EXPECT_GAS_USED(EVMC_SUCCESS, 2 + 5);
+}
+
+TEST_P(evm, clz_osaka)
+{
+    rev = EVMC_OSAKA;
+    const std::vector<std::pair<bytecode, intx::uint256>> cases{
+        {0, 256},
+        {1, 255},
+        {0x8000000000000000000000000000000000000000000000000000000000000000_bytes32, 0},
+        {0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff_bytes32, 0},
+        {0x4000000000000000000000000000000000000000000000000000000000000000_bytes32, 1},
+        {0x7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff_bytes32, 1},
+        {0x0000000000000000000000000000000100000000000000000000000000000000_bytes32, 127},
+        {0x0000000000000000000000000000000000000000000000010000000000000000_bytes32, 191},
+        {0x0000000000000000000000000000000000000000000000008000000000000000_bytes32, 192},
+    };
+    for (const auto& [input, expected_output] : cases)
+    {
+        execute(clz(input) + ret_top());
+        EXPECT_GAS_USED(EVMC_SUCCESS, 23);
+        EXPECT_OUTPUT_INT(expected_output);
+    }
+}
+
+TEST_P(evm, clz_stack_underflow)
+{
+    rev = EVMC_OSAKA;
+    execute(OP_CLZ);
+    EXPECT_STATUS(EVMC_STACK_UNDERFLOW);
+}

test/unittests/instructions_test.cpp

@@ -115,6 +115,7 @@ constexpr bool instruction_only_in_evmone(evmc_revision rev, Opcode op) noexcept
 
     switch (op)
     {
+    case OP_CLZ:
     case OP_BLOBHASH:
     case OP_BLOBBASEFEE:
     case OP_RJUMP:

test/utils/bytecode.hpp

@@ -296,6 +296,11 @@ inline bytecode eq(bytecode a, bytecode b)
     return b + a + OP_EQ;
 }
 
+inline bytecode clz(bytecode a)
+{
+    return a + OP_CLZ;
+}
+
 inline bytecode byte(bytecode a, bytecode n)
 {
     return a + n + OP_BYTE;

test/utils/utils.cpp

@@ -56,6 +56,8 @@ RevisionSchedule to_rev_schedule(std::string_view s)
         return {EVMC_SHANGHAI, EVMC_CANCUN, 15'000};
     if (s == "CancunToPragueAtTime15k")
         return {EVMC_CANCUN, EVMC_PRAGUE, 15'000};
+    if (s == "PragueToOsakaAtTime15k")
+        return {EVMC_PRAGUE, EVMC_OSAKA, 15'000};
 
     const auto single_rev = to_rev(s);
     return {single_rev, single_rev, 0};