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

Wed Aug 16 02:23:37 PDT 2023

vedant-amd added a comment.

In D152278#4590846 <https://reviews.llvm.org/D152278#4590846>, @efriedma wrote:

> I'm not sure why you're having so much trouble with the unequal shift math. The case of unequal shift amount is really just treating the shl as two shifts: one shift by an arbitrary amount, followed by one shift with shift amount equal to the ashr.

I am having trouble with keeping the addition part inside the SextExpr thing, because it always returns back i64 int, but now came up with a better implementation. It seems correct to me, please take a look.

> That said I'd be okay with a patch that bailed out on that case.

In D152278#4590846 <https://reviews.llvm.org/D152278#4590846>, @efriedma wrote:

> I'm not sure why you're having so much trouble with the unequal shift math. The case of unequal shift amount is really just treating the shl as two shifts: one shift by an arbitrary amount, followed by one shift with shift amount equal to the ashr.
>
> That said I'd be okay with a patch that bailed out on that case.

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https://reviews.llvm.org/D152278