This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Problem with tree pass pre


When dealing with an array with known values, pre will evaluate the first iteration of a loop over the elements. The code generator with then jump into the loop. This is at best increasing the size of the code. It also creates inferior code when the hardware supports zero overhead loops. The attached code demonstrates the difference between an unknown array and a known array. The loop size has been picked large enough for cunrolli to not fully unroll the loop. The problem did not exist in gcc 4.8.



Attachment: test.c
Description: Text document


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]