[PATCH] D103597: [AArch64LoadStoreOptimizer] Generate more STPs by renaming registers earlier

[Florian Hahn via Phabricator via llvm-commits]

fhahn added a comment.

In D103597#2808045 <https://reviews.llvm.org/D103597#2808045>, @MeeraN wrote:

> @fhahn in response to your inline comment about performing the renaming registers check twice, if we don't have it we won't try to rename the registers at all, since the check on line 1764 is not reached in our case as we never enter the if statement that contains it. So we brought it earlier to make sure that it tries to rename the registers, if it can. I'll follow-up the rest of the comments in a new diff.

As I mentioned inline, this seems to be skipping a legality check (around line 1734), which is probably the source of the mis-compiles (please add a test for that).

I understand the motivation about trying to find a rename register earlier, but I was wondering if we can detect the need for renaming at a single (possible new) place. It may not be possible, because the register to check for renaming depends on whether we merge forward or backwards.


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