[Bug target/70119] AArch64 should take advantage of implicit truncation of variable shift amount without defining SHIFT_COUNT_TRUNCATED

["collison at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70119

--- Comment #6 from collison at gcc dot gnu.org ---
Author: collison
Date: Thu Jun 29 09:21:57 2017
New Revision: 249774

URL: https://gcc.gnu.org/viewcvs?rev=249774&root=gcc&view=rev
Log:
2017-06-29  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
            Michael Collison <michael.collison@arm.com>

        PR target/70119
        * config/aarch64/aarch64.md (*aarch64_<optab>_reg_<mode>3_mask1):
        New pattern.
        (*aarch64_reg_<mode>3_neg_mask2): New pattern.
        (*aarch64_reg_<mode>3_minus_mask): New pattern.
        (*aarch64_<optab>_reg_di3_mask2): New pattern.
        * config/aarch64/aarch64.c (aarch64_rtx_costs): Account for cost
        of shift when the shift amount is masked with constant equal to
        the size of the mode.
        * config/aarch64/predicates.md (subreg_lowpart_operator): New
        predicate.


2017-06-29  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
            Michael Collison <michael.collison@arm.com>

        PR target/70119
        * gcc.target/aarch64/var_shift_mask_1.c: New test.

Added:
    trunk/gcc/testsuite/gcc.target/aarch64/var_shift_mask_1.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/aarch64/aarch64.c
    trunk/gcc/config/aarch64/aarch64.md
    trunk/gcc/config/aarch64/predicates.md
    trunk/gcc/testsuite/ChangeLog