[NFC][asan] Switch from list to DynInitGlobalsByModule

[vitalybuka]

The patch just switches container from plain
list of globals, to a map grouped by module.

Prepare for incremental poisoning in #101837

[llvmbot]

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Vitaly Buka (vitalybuka)

Changes

Prepare for incremental poisoning, poisoning all
globals for every TU is expensive.

---

Full diff: https://github.com/llvm/llvm-project/pull/101596.diff

1 Files Affected:

• (modified) compiler-rt/lib/asan/asan_globals.cpp (+61-28)

diff --git a/compiler-rt/lib/asan/asan_globals.cpp b/compiler-rt/lib/asan/asan_globals.cpp
index cc5308a24fe89..c7dcc47460e83 100644
--- a/compiler-rt/lib/asan/asan_globals.cpp
+++ b/compiler-rt/lib/asan/asan_globals.cpp
@@ -47,8 +47,6 @@ struct DynInitGlobal {
   bool initialized = false;
   DynInitGlobal *next = nullptr;
 };
-typedef IntrusiveList<DynInitGlobal> DynInitGlobals;
-static DynInitGlobals dynamic_init_globals SANITIZER_GUARDED_BY(mu_for_globals);
 
 // We want to remember where a certain range of globals was registered.
 struct GlobalRegistrationSite {
@@ -72,6 +70,22 @@ static ListOfGlobals &GlobalsByIndicator(uptr odr_indicator)
   return (*globals_by_indicator)[odr_indicator];
 }
 
+using DynInitGLobalsByModule =
+    DenseMap<const char *, IntrusiveList<DynInitGlobal>>;
+
+// TODO: Add a NoDestroy helper, this patter is very common in sanitizers.
+static DynInitGLobalsByModule &DynInitGlobals()
+    SANITIZER_REQUIRES(mu_for_globals) {
+  static DynInitGLobalsByModule *globals_by_module = nullptr;
+  if (!globals_by_module) {
+    alignas(alignof(DynInitGLobalsByModule)) static char
+        placeholder[sizeof(DynInitGLobalsByModule)];
+    globals_by_module = new (placeholder) DynInitGLobalsByModule();
+  }
+
+  return *globals_by_module;
+}
+
 ALWAYS_INLINE void PoisonShadowForGlobal(const Global *g, u8 value) {
   FastPoisonShadow(g->beg, g->size_with_redzone, value);
 }
@@ -257,8 +271,8 @@ static void RegisterGlobal(const Global *g) SANITIZER_REQUIRES(mu_for_globals) {
   AddGlobalToList(list_of_all_globals, g);
 
   if (g->has_dynamic_init) {
-    dynamic_init_globals.push_back(new (GetGlobalLowLevelAllocator())
-                                       DynInitGlobal{*g, false});
+    DynInitGlobals()[g->module_name].push_back(
+        new (GetGlobalLowLevelAllocator()) DynInitGlobal{*g, false});
   }
 }
 
@@ -284,20 +298,42 @@ static void UnregisterGlobal(const Global *g)
   }
 }
 
-void StopInitOrderChecking() {
-  if (!flags()->check_initialization_order)
-    return;
-  Lock lock(&mu_for_globals);
-  flags()->check_initialization_order = false;
-  for (const DynInitGlobal &dyn_g : dynamic_init_globals) {
+static void UnpoisonDynamicGlobals(IntrusiveList<DynInitGlobal> &dyn_globals,
+                                   bool mark_initialized) {
+  for (auto &dyn_g : dyn_globals) {
     const Global *g = &dyn_g.g;
+    if (dyn_g.initialized)
+      continue;
     // Unpoison the whole global.
     PoisonShadowForGlobal(g, 0);
     // Poison redzones back.
     PoisonRedZones(*g);
+    if (mark_initialized)
+      dyn_g.initialized = true;
+  }
+}
+
+static void PoisonDynamicGlobals(
+    const IntrusiveList<DynInitGlobal> &dyn_globals) {
+  for (auto &dyn_g : dyn_globals) {
+    const Global *g = &dyn_g.g;
+    if (dyn_g.initialized)
+      continue;
+    PoisonShadowForGlobal(g, kAsanInitializationOrderMagic);
   }
 }
 
+void StopInitOrderChecking() {
+  if (!flags()->check_initialization_order)
+    return;
+  Lock lock(&mu_for_globals);
+  flags()->check_initialization_order = false;
+  DynInitGlobals().forEach([&](auto &kv) {
+    UnpoisonDynamicGlobals(kv.second, /*mark_initialized=*/false);
+    return true;
+  });
+}
+
 static bool IsASCII(unsigned char c) { return /*0x00 <= c &&*/ c <= 0x7F; }
 
 const char *MaybeDemangleGlobalName(const char *name) {
@@ -458,15 +494,16 @@ void __asan_before_dynamic_init(const char *module_name) {
   Lock lock(&mu_for_globals);
   if (flags()->report_globals >= 3)
     Printf("DynInitPoison module: %s\n", module_name);
-  for (DynInitGlobal &dyn_g : dynamic_init_globals) {
-    const Global *g = &dyn_g.g;
-    if (dyn_g.initialized)
-      continue;
-    if (g->module_name != module_name)
-      PoisonShadowForGlobal(g, kAsanInitializationOrderMagic);
-    else if (!strict_init_order)
-      dyn_g.initialized = true;
-  }
+
+  DynInitGlobals().forEach([&](auto &kv) {
+    if (kv.first != module_name) {
+      PoisonDynamicGlobals(kv.second);
+    } else {
+      UnpoisonDynamicGlobals(kv.second,
+                             /*mark_initialized=*/!strict_init_order);
+    }
+    return true;
+  });
 }
 
 // This method runs immediately after dynamic initialization in each TU, when
@@ -479,13 +516,9 @@ void __asan_after_dynamic_init() {
   Lock lock(&mu_for_globals);
   if (flags()->report_globals >= 3)
     Printf("DynInitUnpoison\n");
-  for (const DynInitGlobal &dyn_g : dynamic_init_globals) {
-    const Global *g = &dyn_g.g;
-    if (!dyn_g.initialized) {
-      // Unpoison the whole global.
-      PoisonShadowForGlobal(g, 0);
-      // Poison redzones back.
-      PoisonRedZones(*g);
-    }
-  }
+
+  DynInitGlobals().forEach([&](auto &kv) {
+    UnpoisonDynamicGlobals(kv.second, /*mark_initialized=*/false);
+    return true;
+  });
 }