index: add method for checking range on DenseBitSet

Author: nia-e

compiler/rustc_index/src/bit_set.rs

@@ -234,6 +234,28 @@ impl<T: Idx> DenseBitSet<T> {
         self.clear_excess_bits();
     }
 
+    /// Checks whether any bit in the given range is a 1.
+    #[inline]
+    pub fn contains_any(&self, elems: impl RangeBounds<T>) -> bool {
+        let Some((start, end)) = inclusive_start_end(elems, self.domain_size) else {
+            return true;
+        };
+        let (start_word_index, start_mask) = word_index_and_mask(start);
+        let (end_word_index, end_mask) = word_index_and_mask(end);
+
+        if self.words[start_word_index] & (!start_mask | !(start_mask - 1)) != 0 {
+            return true;
+        }
+
+        let remaining = start_word_index + 1..end_word_index;
+        if !remaining.is_empty() {
+            self.words[remaining].iter().position(|&w| w != 0).is_some()
+                || self.words[end_word_index] & (end_mask | (end_mask - 1)) != 0
+        } else {
+            false
+        }
+    }
+
     /// Returns `true` if the set has changed.
     #[inline]
     pub fn remove(&mut self, elem: T) -> bool {

src/tools/miri/src/alloc/isolated_alloc.rs

@@ -145,10 +145,7 @@ impl IsolatedAlloc {
             if pinfo.domain_size() < offset_pinfo + size_pinfo {
                 break;
             }
-            // FIXME: is there a more efficient way to check whether the entire range is unset
-            // in the bitset?
-            let range_avail = !(offset_pinfo..offset_pinfo + size_pinfo).any(|i| pinfo.contains(i));
-            if range_avail {
+            if !pinfo.contains_any(offset_pinfo..offset_pinfo + size_pinfo) {
                 pinfo.insert_range(offset_pinfo..offset_pinfo + size_pinfo);
                 // SAFETY: We checked the available bytes after `idx` in the call
                 // to `domain_size` above and asserted there are at least `idx +