[Bug tree-optimization/87505] Vectorizer generates a lot of code for a small loop
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87505 --- Comment #3 from Richard Biener --- Both making i std::size_t or casting (base + 4) to int "fixes" this.
[Bug tree-optimization/87505] Vectorizer generates a lot of code for a small loop
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87505 Richard Biener changed: What|Removed |Added Status|UNCONFIRMED |RESOLVED CC||rguenth at gcc dot gnu.org Resolution|--- |INVALID --- Comment #2 from Richard Biener --- Hmm, we compute the loop iterates ((long unsigned int) base_9(D) - (long unsigned int) (int) base_9(D)) + 3 times. You can probably spot the cases of INT_MAX < base < UINT_MAX not iterating at all (i is sign-extended to std::size_t for the comparison) and base > UINT_MAX where it iterates quite a lot (eventually). We have to account for these cases. If you make the suggested adjustment then of course we know the loop always iterates 4 times. Unless I missed something of course.
[Bug tree-optimization/87505] Vectorizer generates a lot of code for a small loop
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87505 Alexander Monakov changed: What|Removed |Added CC||amonakov at gcc dot gnu.org --- Comment #1 from Alexander Monakov --- This is because 'i' is int while 'base' is size_t. Loop init expression 'int i = base' truncates base to 32 bits, and loop condition first converts i to size_t and then compares in that unsigned type. It's not exactly obvious how many iterations this loop has :) Using the proper type for 'i' results in reasonable code. Perhaps in principle niter analysis could handle this anyway?
