Commit Graph

4 Commits

Author SHA1 Message Date
David Green 0861c87b06 Revert rL357745: [SelectionDAG] Compute known bits of CopyFromReg
Certain optimisations from ConstantHoisting and CGP rely on Selection DAG not
seeing through to the constant in other blocks. Revert this patch while we come
up with a better way to handle that.

I will try to follow this up with some better tests.

llvm-svn: 358113
2019-04-10 18:00:41 +00:00
Piotr Sobczak 0376ac1d94 [SelectionDAG] Compute known bits of CopyFromReg
Summary:
Teach SelectionDAG how to compute known bits of ISD::CopyFromReg if
the virtual reg used has one def only.

This can be particularly useful when calling isBaseWithConstantOffset()
with the ISD::CopyFromReg argument, as more optimizations may get enabled
in the result.

Also add a missing truncation on X86, found by testing of this patch.

Change-Id: Id1c9fceec862d118c54a5b53adf72ada5d6daefa

Reviewers: bogner, craig.topper, RKSimon

Reviewed By: RKSimon

Subscribers: lebedev.ri, nemanjai, jvesely, nhaehnle, javed.absar, jsji, jdoerfert, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59535

llvm-svn: 357745
2019-04-05 07:44:09 +00:00
Piotr Sobczak f896785cb7 [SelectionDAG] Add 2 tests for selection across basic blocks
Summary:
Add tests for selection across basic block boundary:
 * one test containing a buffer load, where part of the offset
   computation is placed in the predecessor of the load
 * similar test, but containing two buffer loads and shared
   computations

Please note that the behaviour being tested will be updated in
a subsequent commit.

This commit was extracted from https://reviews.llvm.org/D59535.

Reviewers: RKSimon

Reviewed By: RKSimon

Subscribers: jvesely, nhaehnle, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59690

llvm-svn: 357149
2019-03-28 07:06:26 +00:00
Neil Henning 76504a4c5e [AMDGPU] Extend the SI Load/Store optimizer to combine more things.
I've extended the load/store optimizer to be able to produce dwordx3
loads and stores, This change allows many more load/stores to be combined,
and results in much more optimal code for our hardware.

Differential Revision: https://reviews.llvm.org/D54042

llvm-svn: 348937
2018-12-12 16:15:21 +00:00