2 Commits

Author	SHA1	Message	Date
Sanjay Patel	3e80019275	[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 llvm-svn: 347478	2018-11-22 19:24:10 +00:00
Sjoerd Meijer	af30f06d5c	[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 llvm-svn: 326882	2018-03-07 09:10:44 +00:00