[llvm] [VPlan] Handle some VPInstructions in may{Read,Write}FromMemory (PR #120058)

[Florian Hahn via llvm-commits]

================
@@ -423,12 +413,16 @@ else.2:
 loop.latch:
   %iv.next = add i64 %iv, 1
   %ec = icmp eq i64 %iv, 64
-  br i1 %ec, label %exit, label %loop.header
+  br i1 %ec, label %exit, label %loop.header, !llvm.loop !0
 
 exit:
   ret void
 }
 
+!0 = distinct !{!0, !1}
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fhahn wrote:

How much work would it be to make the relevant instructions (the ones computing the block masks?) not loop-invariant?


Something like 
```
  %gep.1 = getelementptr inbounds i64, ptr %src.1, i64 %iv
  %x = load i64, %gep.1
  %c1 = icmp eq i64 %x, 0
```

https://github.com/llvm/llvm-project/pull/120058