2 Commits

Author	SHA1	Message	Date
Sanjay Patel	c93c84c762	[DAGCombiner] form 'not' ops ahead of shifts (PR39657) ... We fail to canonicalize IR this way (prefer 'not' ops to arbitrary 'xor'), but that would not matter without this patch because DAGCombiner was reversing that transform. I think we need this transform in the backend regardless of what happens in IR to catch cases where the shift-xor is formed late from GEP or other ops. https://rise4fun.com/Alive/NC1 Name: shl Pre: (-1 << C2) == C1 %shl = shl i8 %x, C2 %r = xor i8 %shl, C1 => %not = xor i8 %x, -1 %r = shl i8 %not, C2 Name: shr Pre: (-1 u>> C2) == C1 %sh = lshr i8 %x, C2 %r = xor i8 %sh, C1 => %not = xor i8 %x, -1 %r = lshr i8 %not, C2 https://bugs.llvm.org/show_bug.cgi?id=39657 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347478 91177308-0d34-0410-b5e6-96231b3b80d8	2018-11-22 19:24:10 +00:00
Sjoerd Meijer	65019820f7	[ARM] Fix for PR36577 ... Don't PerformSHLSimplify if the given node is used by a node that also uses a constant because we may get stuck in an infinite combine loop. bugzilla: https://bugs.llvm.org/show_bug.cgi?id=36577 Patch by Sam Parker. Differential Revision: https://reviews.llvm.org/D44097 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@326882 91177308-0d34-0410-b5e6-96231b3b80d8	2018-03-07 09:10:44 +00:00