Was just wondering how to properly inspect the assembly of my executable, since with femit-asm=main.s I get quite a large file, I don't quite know where to look
#Best way to view asm of executable
dusty cedar
wary forum
Was just wondering how to properly inspect the assembly of my executable, since ...
it might help to use ReleaseSmall to get the size down
although that might also “obfuscate” stuff a bit since itll be more optimized
what exactly are you looking for
dusty cedar
honestly I am just curious to see how much my code gets optimised by the compiler
hot trail
use objdump with -dS flag in the binary. build it in Debug mode.
that’ll show what lines of code correspond to what assembly
or you can use something like https://zig.godbolt.org if your code is pretty small
dusty cedar
use objdump with -dS flag in the binary. build it in Debug mode.
that’ll show w...
any way to have this visually in something like vs code?
hot trail
wdym
steel urchin
i made a gist for this https://gist.github.com/travisstaloch/02820dc30e694a3baa48d2cddaae49a7
haven't used it in while tho
hot trail
there isn't really a need for your own _start function
objdump adds headers to functions that indicate their name and origin, so you can just search by that
steel urchin
i think i added that to reduce the asm size. not sure
(the _start() fn)
no i think thats necessary for some reason. pretty sure you can't do much of anything in _start().
steel urchin
well let me know if there are any issues. i'm sure i put it there for a reason.
regal sable
i think i added that to reduce the asm size. not sure
probably this, the difference is quite a lot
dusty cedar
it might help to use ReleaseSmall to get the size down
this in combination with -fstrip, and just searching for whatever function i am interested in works for my purposes
thanks guys
regal sable
zig does a good bit of startup code, none of which will be there if you make your own _start
modest grail
any way to have this visually in something like vs code?
In CodeLLDB (VS Code plugin) one can see disassembly output
regal sable
this in combination with `-fstrip`, and just searching for whatever function i a...
it doesnt hurt but the -fstrip is unnecessary, releasesmall strips by default
dusty cedar
In CodeLLDB (VS Code plugin) one can see disassembly output
ill take a look!
dusty cedar
it doesnt hurt but the `-fstrip` is unnecessary, releasesmall strips by default
oh lol, makes sense
modest grail
ill take a look!
You need to look up the "LLDB: Toggle Disassembly" command in the Shift+Cmd+P/Shift+Ctrl+P list
dusty cedar
You need to look up the "LLDB: Toggle Disassembly" command in the Shift+Cmd+P/Sh...
how does this work? it doesnt seem to do much
pearl swallow
Just use Compiler Explorer
If you just wanna see how code optimizes, Compiler Explorer is the easiest way
modest grail
how does this work? it doesnt seem to do much
It shows you the disassembly of the current code location you are debugging at.
modest grail
If you just wanna see how code optimizes, Compiler Explorer is the easiest way
IIUC this works for small code snippets, but whenever you want to inspect real code generated for your project, I'm not sure how to use compiler explorer for that and have been always using the debugger's disassembly (combined with some breakpoints). Am I missing something?
pearl swallow
- it's often useful to examine small snippets
- you can run compiler explorer locally to use it with larger projects
modest grail
- you can run compiler explorer locally to use it with larger projects
You mean like offline? I was not aware of this option, nice. Still the debugger's disassembler does everything I need ATM 😉
pearl swallow
Yep
It's open source, you can just download it and host it yourself
And in that mode it'll read files from your local drive if you want
And yeah, debugger works fine if you know what you're doing
It's a bit more confusing for someone who's not used to debuggers
And again, compiler explorer is super nice for testing small snippets