[PATCH 0/5] Add support for operand-specific alignment requirements

[Richard Sandiford <richard.sandiford@arm.com>]

SME has various instructions that require aligned register tuples.
However, the associated tuple modes are already widely used and do
not need to be aligned in other contexts.  It therefore isn't
appropriate to force alignment in TARGET_HARD_REGNO_MODE_OK.

There are also strided loads and stores that require:

- (regno & 0x8) == 0 for 2-register tuples
- (regno & 0xc) == 0 for 4-register tuples

Although the requirements for strided loads and stores could be
enforced by C++ conditions on the insn, it's convenient to handle
them in the same way as alignment.

This series of patches therefore adds a way for register constraints
to specify which start registers are valid and which aren't.  Most of
the details are in the covering note to the first patch.

This is clearly changing a performance-sensitive part of the compiler.
I've tried to ensure that the overhead is only small for targets that
use the new feature.  Almost all of the new code gets optimised away
on targets that don't use the feature.

Richard Sandiford (5):
  Add register filter operand to define_register_constraint
  recog: Handle register filters
  lra: Handle register filters
  ira: Handle register filters
  Add an aligned_register_operand predicate

 gcc/common.md          |  28 ++++++++
 gcc/doc/md.texi        |  41 +++++++++++-
 gcc/doc/tm.texi        |   3 +-
 gcc/doc/tm.texi.in     |   3 +-
 gcc/genconfig.cc       |   2 +
 gcc/genpreds.cc        | 146 ++++++++++++++++++++++++++++++++++++++++-
 gcc/gensupport.cc      |  48 +++++++++++++-
 gcc/gensupport.h       |   3 +
 gcc/ira-build.cc       |   8 +++
 gcc/ira-color.cc       |  10 +++
 gcc/ira-int.h          |  14 ++++
 gcc/ira-lives.cc       |  61 +++++++++++++++++
 gcc/lra-constraints.cc |  13 +++-
 gcc/recog.cc           |  14 +++-
 gcc/recog.h            |  24 ++++++-
 gcc/reginfo.cc         |   5 ++
 gcc/rtl.def            |   6 +-
 gcc/target-globals.cc  |   6 +-
 gcc/target-globals.h   |   3 +
 19 files changed, 421 insertions(+), 17 deletions(-)

-- 
2.25.1