Solidity Profiler

Sometimes it could be excruciating to find out most hungry lines of solidity code. It could happen because of wrong loop condition or overflow, and unclear. We've thought that Solidity profiler is missing part for the Ethereum development eco-system and decided to implement working prototype during hackathon using wide known tools.


We've forked solidity coverage. And after did following fixes:

  • Bulk renaming to save compatibility with the original project.
  • Extend code coverage event with gasleft() value
  • Patch event procession and report generation step, to nicely render it with Istanbul code coverage utils that is a part of solidity coverage

Demo project

To demonstrate how profiler works we take our fork of ecsol project. On that fork we apply has gas optimization that was purposed by Vitalik. So, we were really curious to know the details of our gas optimization.

To get solidity profiler output on sample project do the following:

First, you need the following global dependencies installed:

npm install -g truffle
npm install -g ganache-cli

After clone repositories and perform npm i and npm run profiler

mkdir solidity-profiler-demo
cd solidity-profiler-demo

git clone
cd solidity-profiler
npm i
cd ../

git clone -b feature/solidity-profiler
cd ecsol
npm i

npm run profiler

Discover report file in ecsol/coverage/index.html directory

Challenges we run into

We've made a couple of mistakes in our implementation:

  • We've calculated gas consumption by nested calls in the wrong way.
  • We don't calculate correctly gas consumption by event emission
  • We have a lot of things to improve in visualization in the report

At first, we've decided to extend Istanbul output to add Gas consumption by a line near the line entrance amount.

Further Plas

Our hackathon solution is just a proof of concept and we think that can improve it in the following way:

  • Display min/max/avg/median gas consumption for each line
  • Split complex lines to multiple lines with indentation
  • Make a lot of other improvements and fixes on a long way to the production use ;-)
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