iceCREAM (debugger)
UPDATE IceCream has been removed as of 0.9.0 in favour of more advanced other tools.
Go Ethereum comes with a handy EVM debugger called iceCREAM (after the famous 'SoftICE' kernel debugger). This article will give you a basic understanding of debugging EVM code and operating the iceCREAM debugger.
The interface of the debugger is pretty straight forward and can be accessed from within Ethereal menu (⌘-D)
- In the centre of the window you'll find the main editor which support mutan and serpent.
- On the left side you'll find the disassembled instruction sequence.
- Right top corner are pre-made snippets
- Right side you'll find the simulated data field, endowment, amount of gas & gas price.
- Temp is the VM stack
- Memory is the current in-use memory. Each item is one word (32 bytes)
- Storage inspector
- Debugger CLI
- Debugger log
The debugger supports break points on an instruction level (so don't try to use line numbers). Adding a breakpoint through the debugger CLI (⌘-L) can be done with break <instr number>. When the EVM encounters a breakpoint it will halt the execution and displays the current state of the VM such as the current memory, storage and stack, and allows you to step through the following instructions using the next button (⌘-N).
The debugger supports the following shortcut keys:
- ⌘-L Debugger CLI
- ⌘-R Debug run
- ⌘-N Next sequence (during break)
- ⌘-G Continue (during break)
- ⌘-1 Focus editor
- ⌘-2 Focus data