We help IT Professionals succeed at work.
Get Started

gcc code optimization

effiqua asked
Last Modified: 2014-07-09
I have a C function like below which is part of a file xyz.c and the file is compile using O2 optimization using gcc. The function GetValue() is called almost 200million times  to generate specific data. But for this specific operation cond1 is passed as false, hence code under this condition is never exercise. But, why there is lot of CPU difference in executing GetValue function, when the code chunk 'abc' is commented vs un-commented eventhough the code in that block under (cond1 == true) is not exercised at all.

if the code is commented then GetValue() take - 100 cpu seconds
                     uncomented then GetValue() take  - 120 cpu seconds why ? Is there any problem with GCC optimization ?

inline GetValue(int cond1)

   if (cond1 == true)

      // -- code chunk 'abc'--


Open in new window

Watch Question
Data Warehouse / Database Architect
This problem has been solved!
Unlock 1 Answer and 3 Comments.
See Answer
Why Experts Exchange?

Experts Exchange always has the answer, or at the least points me in the correct direction! It is like having another employee that is extremely experienced.

Jim Murphy
Programmer at Smart IT Solutions

When asked, what has been your best career decision?

Deciding to stick with EE.

Mohamed Asif
Technical Department Head

Being involved with EE helped me to grow personally and professionally.

Carl Webster
CTP, Sr Infrastructure Consultant
Ask ANY Question

Connect with Certified Experts to gain insight and support on specific technology challenges including:

  • Troubleshooting
  • Research
  • Professional Opinions
Did You Know?

We've partnered with two important charities to provide clean water and computer science education to those who need it most. READ MORE