llvm-6502/lib/Transforms
Hal Finkel 245b657ab6 BBVectorize: Better use of TTI->getShuffleCost
When flipping the pair of subvectors that form a vector, if the
vector length is 2, we can use the SK_Reverse shuffle kind to get
more-accurate cost information. Also we can use the SK_ExtractSubvector
shuffle kind to get accurate subvector extraction costs.

The current cost model implementations don't yet seem complex enough
for this to make a difference (thus, there are no test cases with this
commit), but it should help in future.

Depending on how the various targets optimize and combine shuffles in
practice, we might be able to get more-accurate costs by combining the
costs of multiple shuffle kinds. For example, the cost of flipping the
subvector pairs could be modeled as two extractions and two subvector
insertions. These changes, however, should probably be motivated
by specific test cases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173621 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-27 20:07:01 +00:00
..
Hello
InstCombine Use the AttributeSet instead of AttributeWithIndex. 2013-01-27 02:08:22 +00:00
Instrumentation [msan] A comment on ICmp handling logic. 2013-01-25 15:35:29 +00:00
IPO Use the AttributeSet instead of AttributeWithIndex. 2013-01-27 01:57:28 +00:00
Scalar Renamed function IsPotentialUse to IsPotentialRetainableObjPtr. 2013-01-27 06:19:48 +00:00
Utils Re-revert r173342, without losing the compile time improvements, flat 2013-01-27 06:42:03 +00:00
Vectorize BBVectorize: Better use of TTI->getShuffleCost 2013-01-27 20:07:01 +00:00
CMakeLists.txt
LLVMBuild.txt
Makefile