[Bug c/91514] New: optimization needs ficktive memory allocation

[akonn7 at mail dot ru]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91514

            Bug ID: 91514
           Summary: optimization needs ficktive memory allocation
           Product: gcc
           Version: 8.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: akonn7 at mail dot ru
  Target Milestone: ---

Created attachment 46738
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46738&action=edit
Example project for optimized gemm, with optimization bug

In attachment(file gemm.h) exist optimization bug: we need to allocate fictive
memory block for kc, without it we won't get vectorization in inner most loop,
but kc is still dynamically traverse across big memory block for subdivided
matrix C, so i'm suppose optimizer is too paranoid for possible data
dependencies.