This patch introduces alpha-specific version of store_data_bypass_p that
ignores TRAP_IF that would result in assertion failure (and internal
compiler error) in the generic store_data_bypass_p function.

While at it, also remove ev4_ist_c reservation, store_data_bypass_p
can handle the patterns with multiple sets since some time ago.

2022-06-17  Uroš Bizjak  <ubizjak@gmail.com>

gcc/ChangeLog:

    PR target/105209
    * config/alpha/alpha-protos.h (alpha_store_data_bypass_p): New.
    * config/alpha/alpha.cc (alpha_store_data_bypass_p): New function.
    (alpha_store_data_bypass_p_1): Ditto.
    * config/alpha/ev4.md: Use alpha_store_data_bypass_p instead
    of generic store_data_bypass_p.
    (ev4_ist_c): Remove insn reservation.

gcc/testsuite/ChangeLog:

    PR target/105209
    * gcc.target/alpha/pr105209.c: New test.

Tested with a cross-compiler.

Pushed to master.

Uros.