[PATCH] D152278: [SCEV] Compute SCEV for ashr(add(shl(x, n), c), m) instr triplet

[Vedant Paranjape via Phabricator via llvm-commits]

vedant-amd added inline comments.


================
Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:7899
+            // Add constant should be shifted right by AShr amount.
+            APInt AddOperand = AddOperandCI->getValue().ashr(AShrAmt);
+            const SCEV *AddConstant =
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vedant-amd wrote:
> nikic wrote:
> > We should verify that the add constant has lowest n bits unset, to make reassociation valid. It doesn't matter if n==m, but it matters if n!=m.
> Do you mean to say check for unset bits from nth bit to the mth bit ? because anything lower than mth bit will anyways be irrelevant once we right shift by m amount.
I tried to understand this, I am not able to make sense of it. Can you explain further what you mean to say ?


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  https://reviews.llvm.org/D152278/new/

https://reviews.llvm.org/D152278