How does GCC optimize out an unused variable incremented inside a loop?

How does GCC optimize out an unused variable incremented inside a loop?

c gcc compiler-optimization disassembly

c

Why does this memory address %fs:0x28 ( fs[0x28] ) have a random value?

c gcc x86-64 buffer-overflow disassembly

c

Find out what functions a static C library has

c static-libraries dump disassembly

c

Compilers: Understanding assembly code generated from small programs

c linux gcc x86-64 disassembly

c