[PATCH] D71342: [sanitizer] Construct InternalMmapVector without memory allocation.

[Igor Kudrin via Phabricator via llvm-commits]

ikudrin created this revision.
ikudrin added reviewers: kcc, samsonov, eugenis, vitalybuka, earthdok.
ikudrin added projects: Sanitizers, LLVM.

Construction of `InternalMmapVector` is often followed by a call to `reserve()`, which may result in immediate reallocation of the memory for the internal storage. This patch delays that allocation until it is really needed.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D71342

Files:
  compiler-rt/lib/sanitizer_common/sanitizer_common.h
  compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp


Index: compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp
===================================================================
--- compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp
+++ compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp
@@ -131,7 +131,7 @@
     EXPECT_EQ((uptr)i, vector.size());
   }
   InternalMmapVector<uptr> empty_vector;
-  CHECK_GT(empty_vector.capacity(), 0U);
+  CHECK_EQ(empty_vector.capacity(), 0U);
   CHECK_EQ(0U, empty_vector.size());
 }
 
Index: compiler-rt/lib/sanitizer_common/sanitizer_common.h
===================================================================
--- compiler-rt/lib/sanitizer_common/sanitizer_common.h
+++ compiler-rt/lib/sanitizer_common/sanitizer_common.h
@@ -552,7 +552,7 @@
 template<typename T>
 class InternalMmapVector : public InternalMmapVectorNoCtor<T> {
  public:
-  InternalMmapVector() { InternalMmapVectorNoCtor<T>::Initialize(1); }
+  InternalMmapVector() { InternalMmapVectorNoCtor<T>::Initialize(0); }
   explicit InternalMmapVector(uptr cnt) {
     InternalMmapVectorNoCtor<T>::Initialize(cnt);
     this->resize(cnt);


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