gdb's disas command (or asm view in general) is also very helpful, especially if you want to try control-c profiling [1] and then looking at the asm instructions in the neighborhood of where you halted your program.
The tool is called Compiler Explorer; I think Matt just hosted it in his own otherwise unused existing personal domain, but the name famously stuck as it is short and memorable (at $WORK, our private compiler explorer installation is under go/godbolt!).