[fromdoon]

I had once had the opportunity to investigate a heisenbug. We could see that the bug disappeared after turning the optimization off, but our clients were not satisfied and wanted a more detailed explanation and exact root cause analysis.

We were using a proprietary C compiler tool chain provided by our vendor and did not get much help from them either.

Finally, We had to sit down, get the assembly from disassembler and went through whole 800 lines of it. And we found the bug, sitting quietly in one of the pipelines.

I am not a compiler guy, but that day I understood the beauty of compiler optimization.