[compiler-rt] [scudo] Move getResidentPages function (PR #183138)

[via llvm-commits]

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@@ -71,6 +71,21 @@ template <class Derived> class MemMapBase {
     invokeImpl(&Derived::releaseAndZeroPagesToOSImpl, From, Size);
   }
 
+  // Get the total number of resident pages for From to From + Size.
+  // This function can run slowly, and is only expected to be called
+  // from getStats functions where performance does not matter. From represents
+  // the absolute address of the start of a memory region, not a relative offset
+  // from getBase().
+  s64 getResidentPages(uptr From, uptr Size) {
+    if (!isAllocated()) {
+      return 0;
+    }
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ChiaHungDuan wrote:

I think this is better to be handled in each MemMap instance. Otherwise, on the targets which don't support this, if they have region unallocated, it returns 0 and somehow becomes "support getResidentPages"

https://github.com/llvm/llvm-project/pull/183138