richardcavell@xxxxxxxx writes: > I'm compiling using gcc -std=c99 -pedantic -Wall -Wextra, no > optimization, on Ubuntu 10.10 32-bit. Currently my executable size is > 54956 bytes. > > Occasionally I change a small bit of code, and recompile. My > executable file size doesn't change, even when the code definitely > does something different. However, I would like to know what changes > are made. Occasionally I could code thing one way or another, and if > I could shave off a few bytes doing it the other way, I'd like to do > it. > > Why does the executable size not change? Is there some type of > rounding-up going on? How are you measuring the size? If you are using ls -l, then, yes, there are various sorts of rounding to page boundaries going on. Since you are interested in code size, a better approach would be to run the "size" program and look at the "text" field. I don't know what you care about, but note that as a general rule the size of a program running on GNU/Linux does not correlate very well to runtime performance. If you just want to see what changed, use objdump -d and examine the generated assembler code. Or use the --save-temps option with gcc and examine the generated .s file. You can ask gcc to optimize for reduced code size using the -Os option. Ian
