[Bug target/79251] New: PowerPC vec_insert generates store-hit-load if the element number is variable

[meissner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79251

            Bug ID: 79251
           Summary: PowerPC vec_insert generates store-hit-load if the
                    element number is variable
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: meissner at gcc dot gnu.org
  Target Milestone: ---

In looking at the code generated for vec_insert, except for vec_insert of
64-bit items (i.e. long long, long on 64-bit platforms, and double), the
current GCC compiler generates a vector store to a temporary variable on the
stack, and element store to do the insert, and a vector load.

Perhaps there is a sequence that performs better that can be generated when the
element number is variable.