[libc-commits] [PATCH] D130310: [libc] Don't call user comparator function for equal pointers

Alex Brachet via Phabricator via libc-commits libc-commits at lists.llvm.org
Thu Jul 21 14:57:44 PDT 2022

abrachet created this revision.
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The standard says two equal pointers must compare equal so there is no need to call the user comparator function in this case.



Index: libc/src/stdlib/qsort.cpp
--- libc/src/stdlib/qsort.cpp
+++ libc/src/stdlib/qsort.cpp
@@ -42,6 +42,10 @@
   int elem_compare(size_t i, const uint8_t *other) const {
+    // An element must compare equal to itself so we don't need to consult the
+    // user provided comparator.
+    if (get(i) == other)
+      return 0;
     return compare(get(i), other);

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