llvm-project

Commit Graph

Author	SHA1	Message	Date
Sanjay Patel	efd8885772	[InstSimplify] fold negation of sign-bit 0 - X --> X, if X is 0 or the minimum signed value 0 - X --> 0, if X is 0 or the minimum signed value and the sub is NSW I noticed this pattern might be created in the backend after the change from D25485, so we'll want to add a similar fold for the DAG. The use of computeKnownBits in InstSimplify may be something to investigate if the compile time of InstSimplify is noticeable. We could replace computeKnownBits with specific pattern matchers or limit the recursion. Differential Revision: https://reviews.llvm.org/D25785 llvm-svn: 284649	2016-10-19 21:23:45 +00:00
Sanjay Patel	cf26c27478	[InstSimplify] move one and add more tests for potential negation folds llvm-svn: 284627	2016-10-19 18:42:12 +00:00

Author

SHA1

Message

Date

Sanjay Patel

efd8885772

[InstSimplify] fold negation of sign-bit

0 - X --> X, if X is 0 or the minimum signed value
0 - X --> 0, if X is 0 or the minimum signed value and the sub is NSW

I noticed this pattern might be created in the backend after the change from D25485, 
so we'll want to add a similar fold for the DAG.

The use of computeKnownBits in InstSimplify may be something to investigate if the
compile time of InstSimplify is noticeable. We could replace computeKnownBits with 
specific pattern matchers or limit the recursion.

Differential Revision: https://reviews.llvm.org/D25785

llvm-svn: 284649

2016-10-19 21:23:45 +00:00

Sanjay Patel

cf26c27478

[InstSimplify] move one and add more tests for potential negation folds

llvm-svn: 284627

2016-10-19 18:42:12 +00:00

2 Commits