[llvm] [RISCV] Enabled masked interleaved access (PR #149981)

[Philip Reames via llvm-commits]

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@@ -1358,7 +1358,9 @@ class LoopVectorizationCostModel {
       return;
     // Override forced styles if needed.
     // FIXME: Investigate opportunity for fixed vector factor.
+    // FIXME: Support interleave accesses.
     bool EVLIsLegal = UserIC <= 1 && IsScalableVF &&
+                      !InterleaveInfo.hasGroups() &&
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preames wrote:

> It's just that addresses which were originally written to only once may now be written to multiple times. The value written the first time might be incorrect, but it will eventually be overwritten with the correct value.

Just FYI, this reasoning is suspect.  Introducing a duplicate write to the same location is possibly a violation of the memory model.  I'd have to think that through carefully to see if it was, but it's definitely undesirable if we can reasonable avoid.  

(Topic switch)

If I'm following this thread correctly, the issue being theorized here is a problem for any interleave group with EVL right?  Not just the masked variants?

https://github.com/llvm/llvm-project/pull/149981