8 Commits

Author SHA1 Message Date
Johannes Doerfert
41bd26dff9 [Attributor] Delete dead stores
D106185 allows us to determine if a store is needed easily. Using that
knowledge we can start to delete dead stores.

In AAIsDead we now track more state as an instruction can be dead (= the
old optimisitc state) or just "removable". A store instruction can be
removable while being very much alive, e.g., if it stores a constant
into an alloca or internal global. If we would pretend it was dead
instead of only removablewe we would ignore it when we determine what
values a load can see, so that is not what we want.

Differential Revision: https://reviews.llvm.org/D106188
2021-07-26 23:33:36 -05:00
Johannes Doerfert
adddd3dbda [Attributor] Introduce getPotentialCopiesOfStoredValue and use it
This patch introduces `getPotentialCopiesOfStoredValue` which uses
AAPointerInfo to determine all "aliases" or "potential copies" of a
value that is stored into memory. This operation can fail but if it
succeeds it means we can visit all "uses" of a value even if it is
temporarily stored in memory.

There are two users for the function:
  1) `Attributor::checkForAllUses` which will now ignore the value use
     in a store if all "potential copies" can be identified and instead
     be visited. This allows various AAs, including AAPointerInfo
     itself, to look through memory.
  2) `AANoCapture` which uses a custom use tracking through the
     CaptureTracker interface and therefore needs to be thought
     explicitly.

Differential Revision: https://reviews.llvm.org/D106185
2021-07-26 23:33:36 -05:00
Giorgis Georgakoudis
f8c40ed8f8 [OpenMP] Use AAHeapToStack/AAHeapToShared analysis in SPMDization
SPMDization D102307 detects incompatible OpenMP runtime calls to abort converting a target region to SPMD mode. Calls to memory allocation/de-allocation routines kmpc_alloc_shared, kmpc_free_shared are incompatible unless they are removed by AAHeapToStack/AAHeapToShared analysis. This patch extends SPMDization detection to include AAHeapToStack/AAHeapToShared analysis results for enlarging the scope of possible SPMDized regions detected.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D105634
2021-07-22 18:08:37 -07:00
Joseph Huber
7d57639264 [OpenMP] Add new execution mode for SPMD execution with Generic semantics
Qualified kernels can be transformed from generic-mode to SPMD mode using an
optimization in OpenMPOpt. This patch introduces a new execution mode to
indicate kernels that have been transformed from generic-mode to SPMD-mode.
These kernels have SPMD-mode execution, but need generic-mode semantics for
scheduling the blocks and threads. Without this far too few blocks will be
scheduled for a generic region as SPMD mode expects the trip count to be
divided by the number of threads.

Reviewed By: ggeorgakoudis

Differential Revision: https://reviews.llvm.org/D106460
2021-07-21 20:57:28 -04:00
Giorgis Georgakoudis
e8439ec893 [OpenMP] Set RequiresFullRuntime false in SPMDization
SPMDization in D102307 does not change the RequiresFullRuntime argument of kmpc_target_init/deinit calls. However, the constraints of SPMDization detection for converting a target region to SPMD mode should guarantee that the region does not require full runtime support. Hence, this patch sets RequiresFullRuntime to false for improved execution performance.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D105556
2021-07-20 09:54:51 -07:00
Johannes Doerfert
514c033db1 [OpenMP] Detect SPMD compatible kernels and execute them as such
In the spirit of TRegions [0], this patch analyzes a kernel and tracks
if it can be executed in SPMD-mode. If so, we flip the arguments of
the __kmpc_target_init and deinit call to enable the mode. We also
update the `<kernel>_exec_mode` flag to indicate to the runtime we
changed the mode to SPMD.

The code analysis is done interprocedurally by extending the
AAKernelInfo abstract attribute to track SPMD compatibility as well.

[0] https://link.springer.com/chapter/10.1007/978-3-030-28596-8_11

Differential Revision: https://reviews.llvm.org/D102307
2021-07-10 18:44:25 -05:00
Nico Weber
d3e7491333 Revert Attributor patch series
Broke check-clang, see https://reviews.llvm.org/D102307#2869065
Ran `git revert -n ebbe149a6f08535ede848a531a601ae6591cfbc5..269416d41908bb670f67af689155d5ab8eea689a`
2021-07-10 16:15:55 -04:00
Johannes Doerfert
d39179d7fa [OpenMP] Detect SPMD compatible kernels and execute them as such
In the spirit of TRegions [0], this patch analyzes a kernel and tracks
if it can be executed in SPMD-mode. If so, we flip the arguments of
the __kmpc_target_init and deinit call to enable the mode. We also
update the `<kernel>_exec_mode` flag to indicate to the runtime we
changed the mode to SPMD.

The code analysis is done interprocedurally by extending the
AAKernelInfo abstract attribute to track SPMD compatibility as well.

[0] https://link.springer.com/chapter/10.1007/978-3-030-28596-8_11

Differential Revision: https://reviews.llvm.org/D102307
2021-07-10 12:32:51 -05:00