[PATCH] D102073: [TargetLowering] Legalize "vscale x 1" types in more cases

[Sander de Smalen via Phabricator via llvm-commits]

sdesmalen added a comment.

Hi @frasercrmck, thanks for working on this. We're currently investigating legalization of <vscale x 1 x eltty> vectors for SVE, so we'll be able to add some tests for the widening case.



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Comment at: llvm/lib/CodeGen/TargetLoweringBase.cpp:997
+    if (LK.first == TypeExpandInteger) {
+      if (VT.getVectorElementCount() == ElementCount::getScalable(1))
+        report_fatal_error("Cannot legalize this scalable vector");
----------------
I found that when widening <vscale x 1 x eltty>, it shouldn't go down this code-path and hit the fatal error, but rather continue down the code path below (so that it will actually try to widening to <vscale x 2 x eltty>, <vscale x 4 x eltty>, etc. until it has found a legal one.

That said, without a way to test this having the fatal_error is fine for now, especially since we'll soon share some patches that implements the widening of these types with corresponding tests. vscale x 1 types are never legal for SVE and always need widening.


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Comment at: llvm/lib/CodeGen/TargetLoweringBase.cpp:1515
   LegalizeTypeAction TA = getTypeAction(Context, VT);
-  if (EltCnt.getKnownMinValue() != 1 &&
+  if ((EltCnt.isScalable() || EltCnt.getFixedValue() != 1) &&
       (TA == TypeWidenVector || TA == TypePromoteInteger)) {
----------------
Is this equivalent to `EltCnt.isVector()` ? (I assume we can assert that a minimum value of 0 is not allowed)


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D102073/new/

https://reviews.llvm.org/D102073