[PATCH] D36443: [InstCombine] Support pulling left shifts through a subtract with constant LHS

Eli Friedman via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Tue Aug 8 13:03:13 PDT 2017

efriedma accepted this revision.
efriedma added a comment.
This revision is now accepted and ready to land.

LGTM, with one small question.

Comment at: lib/Transforms/InstCombine/InstCombineShifts.cpp:518
+      if (isLeftShift && Op0BO->getOpcode() == Instruction::Sub &&
+          match(Op0BO->getOperand(0), m_APInt(Op0C))) {
+        Constant *NewRHS = ConstantExpr::get(I.getOpcode(),
It looks like this can match a vector?  If it can, please add a vector testcase.


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