Compiling process

[modest copper]

Just a quick question, what is the compiling process called where you have your source files, they turn into obj, linked then you get your executable? I wanted to find some videos or documentation to learn more about this process. Thanks!!

[wispy zinc]

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[bleak crag]

Linking

I mean the last part is linking

The first part is compilation and assembly

Compilation per se just turns source files (text) into assembly files (text too). Only when you assemble those you get object files (binary)

[mint prism]

that isn't the only approach, I would doubt it is even the statistically dominant one

gcc does that, msvc and clang - don't

[bleak crag]

I don't think even gcc does it anymore

Oh wait not it probably does, that's why it needs binutils

But idk if they actually go through the effort of generating an assembly file, don't they just keep it in memory and somehow pass that to the assembler?
Anyway I'm curious, what does clang/llvm do different?

I know I can tell clang to generate assembly files with pretty much the same command line options as with gcc, but maybe they just put that for compatibility reasons

[mint prism]

that is compatibility, as far as I know normally the frontend generates just binary intermediate representation (this one can also be dumped in the text format), that one is transformed for optimizations and the backend generates machine code directly

as for gcc:

$ strace -fe openat gcc x.c|&grep -E 'O_(WRONLY|RDWR)'
openat(AT_FDCWD, "/tmp/cct6f6UK.s", O_RDWR|O_CREAT|O_EXCL, 0600) = 3
[pid 61621] openat(AT_FDCWD, "/tmp/cct6f6UK.s", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 3
openat(AT_FDCWD, "/tmp/ccHfVZFG.o", O_RDWR|O_CREAT|O_EXCL, 0600) = 3
[pid 61622] openat(AT_FDCWD, "/tmp/ccHfVZFG.o", O_RDWR|O_CREAT|O_TRUNC, 0666) = 3
openat(AT_FDCWD, "/tmp/ccZvGItH.res", O_RDWR|O_CREAT|O_EXCL, 0600) = 3
[pid 61623] openat(AT_FDCWD, "/tmp/ccROl07Z.cdtor.c", O_RDWR|O_CREAT|O_EXCL, 0600) = 3
[pid 61623] openat(AT_FDCWD, "/tmp/cc0zDhqN.cdtor.o", O_RDWR|O_CREAT|O_EXCL, 0600) = 3
[pid 61624] openat(AT_FDCWD, "a.out", O_RDWR|O_CREAT|O_TRUNC, 0666) = 3

[bleak crag]

That's interesting, I wonder how that interferes with inline assembly

in the gcc mode of operation you just emit the inline assembly, does clang need to also call a completely different assembly front end?

Which would be a kinda trivial one I suppose

[mint prism]

I don't know the details, but for sure it is more sophisticated than in gcc, iirc it has even msvc-compatibility mode when it is the compiler role to infer clobbered registers

so it's not a dumb copy-paste

or even just blindly assemble and paste machine code

[bleak crag]

That's neat, the gcc syntax is a bit of a headache

The extended one

[mint prism]

ineed, and msvc had an easy one for x86-32, but dropped for x86-64 and I thiiiiink I've seen that clang can do MS-way in x86-64 as well

[bleak crag]

I feel like having a full blown assembler let's you do some powerful and cursed stuff with inline assembly tho, like you could pass inline directives to define a symbol within it and have some kind of nested function definition

Or trick the compiler into jumping from one function to another

I wonder if there are sanity checks for that

[livid kindle]

Hi

Does anyone use vs code here

I have problem while running code

Code is not running

Give me suggestions what to do