From cb4e20aa2a07e355935306a962b562ad83d79fde Mon Sep 17 00:00:00 2001
From: Alex Beregszaszi <alex@rtfs.hu>
Date: Thu, 18 Jul 2019 23:12:29 +0100
Subject: [PATCH] Introduce particle gas costs for Istanbul

---
 lib/evmone/analysis.cpp     | 15 +++++++++++++--
 lib/evmone/analysis.hpp     |  2 ++
 lib/evmone/execution.cpp    |  6 ++++++
 lib/evmone/instructions.cpp |  8 ++++++--
 4 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/lib/evmone/analysis.cpp b/lib/evmone/analysis.cpp
index 3089cf6890..54c4555cf8 100644
--- a/lib/evmone/analysis.cpp
+++ b/lib/evmone/analysis.cpp
@@ -50,6 +50,15 @@ evmc_call_kind op2call_kind(uint8_t opcode) noexcept
 code_analysis analyze(
     const exec_fn_table& fns, evmc_revision rev, const uint8_t* code, size_t code_size) noexcept
 {
+    // FIXME: change to an if outside
+    static auto to_gas_cost = [&](int64_t gas_cost)
+    {
+        if (rev >= EVMC_ISTANBUL)
+            return static_cast<int>(gas_cost / particles_per_gas);
+        else
+            return static_cast<int>(gas_cost);
+    };
+
     code_analysis analysis;
     // TODO: Check if final result exceeds the reservation.
     analysis.instrs.reserve(code_size + 1);
@@ -113,11 +122,13 @@ code_analysis analyze(
         else if (c >= OP_SWAP1 && c <= OP_SWAP16)
             instr.arg.p.number = c - OP_SWAP1 + 1;
         else if (c == OP_GAS)
-            instr.arg.p.number = static_cast<int>(block->gas_cost);
+        {
+            instr.arg.p.number = to_gas_cost(block->gas_cost);
+        }
         else if (c == OP_DELEGATECALL || c == OP_CALL || c == OP_CALLCODE || c == OP_STATICCALL ||
                  c == OP_CREATE || c == OP_CREATE2)
         {
-            instr.arg.p.number = static_cast<int>(block->gas_cost);
+            instr.arg.p.number = to_gas_cost(block->gas_cost);
             instr.arg.p.call_kind = op2call_kind(c == OP_STATICCALL ? uint8_t{OP_CALL} : c);
         }
         else if (c == OP_PC)
diff --git a/lib/evmone/analysis.hpp b/lib/evmone/analysis.hpp
index 037ae013b1..a328422a90 100644
--- a/lib/evmone/analysis.hpp
+++ b/lib/evmone/analysis.hpp
@@ -32,6 +32,8 @@ static_assert(continue_status == 0, "The 'continue' status is not 0");
 /// The EVMC_INTERNAL_ERROR MUST NOT be used in evmone for any other case.
 constexpr auto stop_status = EVMC_INTERNAL_ERROR;
 
+constexpr unsigned particles_per_gas = 1000;
+
 /// The stack for 256-bit EVM words.
 ///
 /// This implementation reserves memory inplace for all possible stack items (1024),
diff --git a/lib/evmone/execution.cpp b/lib/evmone/execution.cpp
index af5169a460..c46b3b7a17 100644
--- a/lib/evmone/execution.cpp
+++ b/lib/evmone/execution.cpp
@@ -28,6 +28,8 @@ evmc_result execute(evmc_instance*, evmc_context* ctx, evmc_revision rev, const
     state->host = evmc::HostContext{ctx};
     state->gas_left = msg->gas;
     state->rev = rev;
+    if (rev >= EVMC_ISTANBUL)
+        state->gas_left *= particles_per_gas;
     while (state->status == continue_status)
     {
         auto& instr = analysis.instrs[state->pc];
@@ -44,7 +46,11 @@ evmc_result execute(evmc_instance*, evmc_context* ctx, evmc_revision rev, const
     result.status_code = state->status != stop_status ? state->status : continue_status;
 
     if (result.status_code == EVMC_SUCCESS || result.status_code == EVMC_REVERT)
+    {
         result.gas_left = state->gas_left;
+        if (rev >= EVMC_ISTANBUL)
+            result.gas_left /= particles_per_gas;
+    }
 
     if (state->output_size > 0)
     {
diff --git a/lib/evmone/instructions.cpp b/lib/evmone/instructions.cpp
index f12390c1b6..271b712baf 100644
--- a/lib/evmone/instructions.cpp
+++ b/lib/evmone/instructions.cpp
@@ -37,8 +37,9 @@ bool check_memory(execution_state& state, const uint256& offset, const uint256&
     const auto new_size = o + s;
     if (m < new_size)
     {
+        auto cost_per_word = (state.rev >= EVMC_ISTANBUL) ? 3 : 3 * particles_per_gas;
         auto w = (new_size + 31) / 32;
-        auto new_cost = 3 * w + w * w / 512;
+        auto new_cost = cost_per_word * w + w * w / 512;
         auto cost = new_cost - state.memory_prev_cost;
         state.memory_prev_cost = new_cost;
 
@@ -514,7 +515,10 @@ void op_gas(execution_state& state, instr_argument arg) noexcept
 {
     const auto correction = state.current_block_cost - arg.p.number;
     const auto gas = static_cast<uint64_t>(state.gas_left + correction);
-    state.stack.push(gas);
+    if (state.rev >= EVMC_ISTANBUL)
+        state.stack.push(gas / particles_per_gas);
+    else
+        state.stack.push(gas);
 }
 
 void op_gasprice(execution_state& state, instr_argument) noexcept