Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
[PowerPC] avoid masking already-zero bits in BitPermutationSelector
The current BitPermutationSelector generates a code to build a value by tracking two types of bits: ConstZero and Variable. ConstZero means a bit we need to mask off and Variable is a bit we copy from an input value. This patch add third type of bits VariableKnownToBeZero caused by AssertZext node or zero-extending load node. VariableKnownToBeZero means a bit comes from an input value, but it is known to be already zero. So we do not need to mask them. VariableKnownToBeZero enhances flexibility to group bits, since we can avoid redundant masking for these bits. This patch also renames "HasZero" to "NeedMask" since now we may skip masking even when we have zeros (of type VariableKnownToBeZero). Differential Revision: https://reviews.llvm.org/D48025 llvm-svn: 344347
- Loading branch information
Showing
5 changed files
with
143 additions
and
28 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters