[Bug tree-optimization/98953] New: Failure to optimize two reads from adjacent addresses into one

[gabravier at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98953

            Bug ID: 98953
           Summary: Failure to optimize two reads from adjacent addresses
                    into one
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gabravier at gmail dot com
  Target Milestone: ---

int f(uint8_t *read, size_t abs)
{
    return read[abs] + 0x100 * read[abs + 1];;
}

This can be optimized to (ignoring aliasing) `return *(uint16_t *)(read +
abs)`. This transformation is done by LLVM, but not by GCC.