[Mlir-commits] [mlir] [mlir][ArmSVE] Add convert_to/from_svbool ops (PR #68586)

[Benjamin Maxwell]

================
@@ -481,10 +500,39 @@ class IsScalableVectorOfLengthPred<list<int> allowedLengths> :
                            == }]
                          # allowedlength>)>]>;
 
+// Normalizes an index so it can be bounds checked.
+// Negative values are mapped to their absolute value.
+//  - These are used to index in reverse (i.e. index -1 would be the last element)
+// Positive values are mapped to their value + 1.
+//  - This results the same range of values as the negative indices
+// This allows bounds checking to be: len(list) >= NormalizeIndex<idx>.ret.
+class NormalizeIndex<int value> {
+  int ret = !if(!lt(value, 0), !sub(0, value), !add(value, 1));
+}
----------------
MacDue wrote:

Rewrote the comment here to:
```
// Normalizes an index so the indices in both directions have the same value.
// For example, when indexing forwards index 2 is the third element. When
// indexing in reverse the third element is -3. This helper would map both of
// these to the "normalized" index of 3. This makes the bounds checking in
// IsNthDimSizeIsOneOfPred simpler (see first CPred).
```

https://github.com/llvm/llvm-project/pull/68586