[PATCH] D138508: [TargetLowering] Teach DemandedBits about VSCALE

[Mikael Holmén via Phabricator via llvm-commits]

uabelho added inline comments.


================
Comment at: llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp:1137
+    int64_t VScaleResultUpperbound =
+        *MaxVScale * Op.getConstantOperandAPInt(0).getSExtValue();
+    bool Negative = VScaleResultUpperbound < 0;
----------------
With an UBSan build we get this
```
../lib/CodeGen/SelectionDAG/TargetLowering.cpp:1137:20: runtime error: signed integer overflow: 16 * -9223372036854775808 cannot be represented in type 'long'
```
when running lit tests
```
Failed Tests (1):
  LLVM :: CodeGen/AArch64/sve-gather-scatter-addr-opts.ll
```

I get it also on latest main (d2b070d3c95c5).


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D138508/new/

https://reviews.llvm.org/D138508