"Rohit Arul Raj" <[EMAIL PROTECTED]> writes: > I am upgrading my cross-compiler from 3.4.6 to 4.1.1. It has built > successfully. But while running the test suites, i am getting lots of > run time errors during optimization tests (Mostly size optimization - > Os). But the same code with same level of optimization works fine with > 3.4.6. > > 1. What are the differences in implementation of optimization levels > of 3.4.6 and 4.1.1?
The 4.1.1 optimizers are very different from the 3.4.6 optimizers. 4.1.1 uses the tree-ssa framework which was introduced in 4.0. > 2. For 4.1.1, The same test code works with all levels of optimization > except -Os. > Other than flags, what are the ways in which the implementation of > Optimization levels differ? -Os is like -O2 except that it sets the global variable optimize_size. Grep for optimize_size to see the differences. Ian