[llvm] Allow empty range attribute and add assert for full range (PR #100601)

[Nikita Popov via llvm-commits]

================
@@ -3109,8 +3109,8 @@ bool LLParser::parseRangeAttr(AttrBuilder &B) {
   if (ParseAPSInt(BitWidth, Lower) ||
       parseToken(lltok::comma, "expected ','") || ParseAPSInt(BitWidth, Upper))
     return true;
-  if (Lower == Upper)
-    return tokError("the range should not represent the full or empty set!");
+  if (Lower == Upper && !Lower.isMinValue())
----------------
nikic wrote:

```suggestion
  if (Lower == Upper && !Lower.isZero())
```

https://github.com/llvm/llvm-project/pull/100601