[PATCH] [x86] add a reassociation optimization to increase ILP via the MachineCombiner pass

[Gerolf Hoflehner]

Hi Sanjay,

is this on phabricator?

My understanding of the code is that you reassociate patterns like A = ?? op ??; B = A op X; C = B op Y, but your comments suggest A’s statement can use any operand. Please check in isReassocCandidate():

+  // We must match a simple chain of dependent ops.
+  if (checkPrevOpcode && MI1->getOpcode() != AssocOpcode)
+    return nullptr;

and note that for all incarnations checkPrevOpcode is ‘true’. Or do I miss something?

Cheers
Gerolf


http://reviews.llvm.org/D10321

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