[PATCH 7/8] [BRIGFE] phsa-specific optimizations

[Pekka Jääskeläinen]

Committed as r259957.

On Fri, May 4, 2018 at 5:02 PM, Pekka Jääskeläinen <pekka@parmance.com> wrote:
> Add flag -fassume-phsa that is on by default. If -fno-assume-phsa
> is given, these optimizations are disabled.
>
> With this flag, gccbrig can generate GENERIC that assumes we are
> targeting a phsa-runtime based implementation, which allows us
> to expose the work-item context accesses to retrieve WI IDs etc.
> which helps optimizers.
>
> First optimization that takes advantage of this is to get rid of
> the setworkitemid calls whenever we have non-inlined calls that
> use IDs internally.
>
> Other optimizations added in this commit:
>
> - expand absoluteid to similar level of simplicity as workitemid.
> At the moment absoluteid is the best indexing ID to end up with
> WG vectorization.
> - propagate ID variables closer to their uses. This is mainly
> to avoid known useless casts, which confuse at least scalar
> evolution analysis.
> - use signed long long for storing IDs. Unsigned integers have
> defined wraparound semantics, which confuse at least scalar
> evolution analysis, leading to unvectorizable WI loops.
> - also refactor some BRIG function generation helpers to brig_function.
> - no point in having the wi-loop as a for-loop. It's really
> a do...while and SCEV can analyze it just fine still.
> - add consts to ptrs etc. in BRIG builtin defs.
> Improves optimization opportunities.
> - add qualifiers to generated function parameters.
> Const and restrict on the hidden local/private pointers,
> the arg buffer and the context pointer help some optimizations.
> ---
>  gcc/brig-builtins.def                              |  27 +-
>  gcc/brig/brigfrontend/brig-basic-inst-handler.cc   | 172 +---
>  gcc/brig/brigfrontend/brig-branch-inst-handler.cc  |  21 +-
>  gcc/brig/brigfrontend/brig-cmp-inst-handler.cc     |   6 +-
>  gcc/brig/brigfrontend/brig-code-entry-handler.cc   | 503 +----------
>  gcc/brig/brigfrontend/brig-code-entry-handler.h    |  21 -
>  gcc/brig/brigfrontend/brig-control-handler.cc      |  20 +-
>  gcc/brig/brigfrontend/brig-cvt-inst-handler.cc     |   6 +
>  gcc/brig/brigfrontend/brig-function-handler.cc     |  89 +-
>  gcc/brig/brigfrontend/brig-function.cc             | 925
> +++++++++++++++++++--
>  gcc/brig/brigfrontend/brig-function.h              |  43 +
>  gcc/brig/brigfrontend/brig-label-handler.cc        |   3 +
>  gcc/brig/brigfrontend/brig-lane-inst-handler.cc    |   2 +-
>  gcc/brig/brigfrontend/brig-mem-inst-handler.cc     |   7 +-
>  gcc/brig/brigfrontend/phsa.h                       |   9 +
>  gcc/brig/lang.opt                                  |   5 +
>  gcc/builtin-types.def                              |   4 +
>  gcc/testsuite/brig.dg/test/gimple/smoke_test.hsail |  10 +-
>  libhsail-rt/include/internal/phsa-rt.h             |   1 -
>  libhsail-rt/include/internal/workitems.h           |  50 +-
>  libhsail-rt/rt/workitems.c                         |  84 +-
>  21 files changed, 1195 insertions(+), 813 deletions(-)
>