[NFC][lsan] Simplify root_regions initialization

GitOrigin-RevId: 64d44208246b76772b2b04980234bd75d546a4b4
diff --git a/lib/lsan/lsan_common.cpp b/lib/lsan/lsan_common.cpp
index 139abd0..308dbb3 100644
--- a/lib/lsan/lsan_common.cpp
+++ b/lib/lsan/lsan_common.cpp
@@ -131,18 +131,13 @@
   return suppression_ctx;
 }
 
-static InternalMmapVector<RootRegion> *root_regions;
+static InternalMmapVectorNoCtor<RootRegion> root_regions;
 
-InternalMmapVector<RootRegion> const *GetRootRegions() { return root_regions; }
-
-void InitializeRootRegions() {
-  CHECK(!root_regions);
-  ALIGNED(64) static char placeholder[sizeof(InternalMmapVector<RootRegion>)];
-  root_regions = new (placeholder) InternalMmapVector<RootRegion>();
+InternalMmapVectorNoCtor<RootRegion> const *GetRootRegions() {
+  return &root_regions;
 }
 
 void InitCommonLsan() {
-  InitializeRootRegions();
   if (common_flags()->detect_leaks) {
     // Initialization which can fail or print warnings should only be done if
     // LSan is actually enabled.
@@ -426,10 +421,8 @@
 // Scans root regions for heap pointers.
 static void ProcessRootRegions(Frontier *frontier) {
   if (!flags()->use_root_regions) return;
-  CHECK(root_regions);
-  for (uptr i = 0; i < root_regions->size(); i++) {
-    ProcessRootRegion(frontier, (*root_regions)[i]);
-  }
+  for (uptr i = 0; i < root_regions.size(); i++)
+    ProcessRootRegion(frontier, root_regions[i]);
 }
 
 static void FloodFillTag(Frontier *frontier, ChunkTag tag) {
@@ -966,9 +959,8 @@
 void __lsan_register_root_region(const void *begin, uptr size) {
 #if CAN_SANITIZE_LEAKS
   Lock l(&global_mutex);
-  CHECK(root_regions);
   RootRegion region = {reinterpret_cast<uptr>(begin), size};
-  root_regions->push_back(region);
+  root_regions.push_back(region);
   VReport(1, "Registered root region at %p of size %zu\n", begin, size);
 #endif // CAN_SANITIZE_LEAKS
 }
@@ -977,15 +969,14 @@
 void __lsan_unregister_root_region(const void *begin, uptr size) {
 #if CAN_SANITIZE_LEAKS
   Lock l(&global_mutex);
-  CHECK(root_regions);
   bool removed = false;
-  for (uptr i = 0; i < root_regions->size(); i++) {
-    RootRegion region = (*root_regions)[i];
+  for (uptr i = 0; i < root_regions.size(); i++) {
+    RootRegion region = root_regions[i];
     if (region.begin == reinterpret_cast<uptr>(begin) && region.size == size) {
       removed = true;
-      uptr last_index = root_regions->size() - 1;
-      (*root_regions)[i] = (*root_regions)[last_index];
-      root_regions->pop_back();
+      uptr last_index = root_regions.size() - 1;
+      root_regions[i] = root_regions[last_index];
+      root_regions.pop_back();
       VReport(1, "Unregistered root region at %p of size %zu\n", begin, size);
       break;
     }
diff --git a/lib/lsan/lsan_common.h b/lib/lsan/lsan_common.h
index 93b7d4e..1f828fa 100644
--- a/lib/lsan/lsan_common.h
+++ b/lib/lsan/lsan_common.h
@@ -140,7 +140,7 @@
   bool success = false;
 };
 
-InternalMmapVector<RootRegion> const *GetRootRegions();
+InternalMmapVectorNoCtor<RootRegion> const *GetRootRegions();
 void ScanRootRegion(Frontier *frontier, RootRegion const &region,
                     uptr region_begin, uptr region_end, bool is_readable);
 void ForEachExtraStackRangeCb(uptr begin, uptr end, void* arg);
diff --git a/lib/lsan/lsan_common_mac.cpp b/lib/lsan/lsan_common_mac.cpp
index 8516a17..4301dcc 100644
--- a/lib/lsan/lsan_common_mac.cpp
+++ b/lib/lsan/lsan_common_mac.cpp
@@ -149,7 +149,7 @@
   kern_return_t err = KERN_SUCCESS;
   mach_msg_type_number_t count = VM_REGION_SUBMAP_INFO_COUNT_64;
 
-  InternalMmapVector<RootRegion> const *root_regions = GetRootRegions();
+  InternalMmapVectorNoCtor<RootRegion> const *root_regions = GetRootRegions();
 
   while (err == KERN_SUCCESS) {
     struct vm_region_submap_info_64 info;
diff --git a/lib/sanitizer_common/sanitizer_linux.cpp b/lib/sanitizer_common/sanitizer_linux.cpp
index d4fba65..aa59d97 100644
--- a/lib/sanitizer_common/sanitizer_linux.cpp
+++ b/lib/sanitizer_common/sanitizer_linux.cpp
@@ -170,14 +170,14 @@
 
 ScopedBlockSignals::~ScopedBlockSignals() { SetSigProcMask(&saved_, nullptr); }
 
-#if SANITIZER_LINUX && defined(__x86_64__)
-#include "sanitizer_syscall_linux_x86_64.inc"
-#elif SANITIZER_LINUX && SANITIZER_RISCV64
-#include "sanitizer_syscall_linux_riscv64.inc"
-#elif SANITIZER_LINUX && defined(__aarch64__)
-#include "sanitizer_syscall_linux_aarch64.inc"
-#elif SANITIZER_LINUX && defined(__arm__)
-#include "sanitizer_syscall_linux_arm.inc"
+#  if SANITIZER_LINUX && defined(__x86_64__)
+#    include "sanitizer_syscall_linux_x86_64.inc"
+#  elif SANITIZER_LINUX && SANITIZER_RISCV64
+#    include "sanitizer_syscall_linux_riscv64.inc"
+#  elif SANITIZER_LINUX && defined(__aarch64__)
+#    include "sanitizer_syscall_linux_aarch64.inc"
+#  elif SANITIZER_LINUX && defined(__arm__)
+#    include "sanitizer_syscall_linux_arm.inc"
 #  elif SANITIZER_LINUX && defined(__hexagon__)
 #    include "sanitizer_syscall_linux_hexagon.inc"
 #  else