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Writing Efficient C Code?

posted by LaminatorX on Sunday March 16 2014, @03:28AM   
from the premature-optimization-is-the-root-of-all-evil dept.

Subsentient writes:

"I've been writing C for quite some time, but I never followed good conventions I'm afraid, and I never payed much attention to the optimization tricks of the higher C programmers. Sure, I use const when I can, I use the pointer methods for manual string copying, I even use register for all the good that does with modern compilers, but now, I'm trying to write a C-string handling library for personal use, but I need speed, and I really don't want to use inline ASM. So, I am wondering, what would other Soylenters do to write efficient, pure, standards-compliant C?"

• Re:Never trust the compiler (Score: 1) by smellotron on Sunday March 16 2014, @08:30PM

  by smellotron (3346) on Sunday March 16 2014, @08:30PM (#17260)

  For compilers on the order of gcc and clang, and probably even Visual C++, the compiler writers know more than you could possibly imagine about creating efficient machine code.

  When optimizing, a large part of the value in inspecting the compiler-generated object code is in identifying pessimizations that the compiler was forced to make to follow the language standard. It is very common in code that I write (not games, but still latency-sensitive) that some trivial reordering of operations in the C code will reduce or remove stack usage, or replace a nested function call with a tail call. Especially because compiler writers tend to be the sharpest optimizers in the room, there is value in double-checking their output to detect data-dependency/optimization bugs in your code.

  Parent