Reduce the size of quarantine cache in ASAN_LOW_MEMORY configuration.

[alekseyshl]

Summary

Experiments show that on Android the current values result in too much
of the memory consumption for all quarantined chunks.

[eugenis]

LGTM

lib/asan/asan_allocator.cc

235

1 << 16

lib/asan/asan_internal.h

39

Please remove a line in lib/asan/CMakeLists.txt that sets ASAN_LOW_MEMORY for Android.

[eugenis]

Btw ASAN_LOW_MEMORY was set for all 32-bit targets in r171052 by kcc.
I don't understand why.
IMHO, it should be a property of environment (i.e. OS), not architecture. If necessary, we can always test for 32-bit platform directly. And we do, see all the FIRST_32_SECOND_64 macros!

I'd support removing "|| (SANITIZER_WORDSIZE == 32)" from this definition.

[alekseyshl]

• Define ASAN_LOW_MEMORY based on the target platform, not bitness.

[alekseyshl]

lib/asan/asan_allocator.cc

235

Sure, but doesn't it make it a bit less cryptic using 64 and Kb (1 << 10) than 1 << 16?

[eugenis]

lib/asan/asan_allocator.cc

235

it's a matter of taste, I guess
It's also consistent with other constants in this file, like 1<<18 and 1<<20.

[alekseyshl]

• Addressing comments.

[alekseyshl]

Done

[kubamracek]

The Darwin bots are failing the ThreadedQuarantineTest test: http://lab.llvm.org:8080/green/job/clang-stage1-configure-RA_check/25044/console

Can you please take a look?

[alekseyshl]

Looking

lib/asan/CMakeLists.txt

 include_directories(..)
 
 set(ASAN_CFLAGS ${SANITIZER_COMMON_CFLAGS})
 append_rtti_flag(OFF ASAN_CFLAGS)
 
 set(ASAN_DYNAMIC_LINK_FLAGS)
 
 if(ANDROID)
-  list(APPEND ASAN_COMMON_DEFINITIONS
-    ASAN_LOW_MEMORY=1)
 # On Android, -z global does not do what it is documented to do.
 # On Android, -z global moves the library ahead in the lookup order,
 # placing it right after the LD_PRELOADs. This is used to compensate for the fact
 # that Android linker does not look at the dependencies of the main executable
 # that aren't dependencies of the current DSO when resolving symbols from said DSO.
 # As a net result, this allows running ASan executables without LD_PRELOAD-ing the
 # ASan runtime library.
 # The above is applicable to L MR1 or newer.

lib/asan/asan_allocator.cc

void AllocatorOptions::CopyTo(Flags *f, CommonFlags *cf) {
   f->alloc_dealloc_mismatch = alloc_dealloc_mismatch;
   cf->allocator_release_to_os_interval_ms = release_to_os_interval_ms;
 }
 
 struct Allocator {
   static const uptr kMaxAllowedMallocSize =
       FIRST_32_SECOND_64(3UL << 30, 1ULL << 40);
   static const uptr kMaxThreadLocalQuarantine =
-      FIRST_32_SECOND_64(1 << 18, 1 << 20);
+      // It is not advised to go lower than 64Kb, otherwise quarantine batches
+      // pushed from thread local quarantine to global one will create too much
+      // overhead. One quarantine batch size is 8Kb and it  holds up to 1021
+      // chunk, which amounts to 1/8 memory overhead per batch when thread local
+      // quarantine is set to 64Kb.
+      (ASAN_LOW_MEMORY) ? 1 << 16 : FIRST_32_SECOND_64(1 << 18, 1 << 20);
 
   AsanAllocator allocator;
   AsanQuarantine quarantine;
   StaticSpinMutex fallback_mutex;
   AllocatorCache fallback_allocator_cache;
   QuarantineCache fallback_quarantine_cache;
 
   // ------------------- Options --------------------------

lib/asan/asan_flags.cc

if (f->quarantine_size >= 0 && f->quarantine_size_mb >= 0) {
     Report("%s: please use either 'quarantine_size' (deprecated) or "
            "quarantine_size_mb, but not both\n", SanitizerToolName);
     Die();
   }
   if (f->quarantine_size >= 0)
     f->quarantine_size_mb = f->quarantine_size >> 20;
   if (f->quarantine_size_mb < 0) {
     const int kDefaultQuarantineSizeMb =
-        (ASAN_LOW_MEMORY) ? 1UL << 6 : 1UL << 8;
+        (ASAN_LOW_MEMORY) ? 1UL << 4 : 1UL << 8;
     f->quarantine_size_mb = kDefaultQuarantineSizeMb;
   }
   if (!f->replace_str && common_flags()->intercept_strlen) {
     Report("WARNING: strlen interceptor is enabled even though replace_str=0. "
            "Use intercept_strlen=0 to disable it.");
   }
   if (!f->replace_str && common_flags()->intercept_strchr) {
     Report("WARNING: strchr* interceptors are enabled even though "

lib/asan/asan_internal.h

 // If set, asan will intercept C++ exception api call(s).
 #ifndef ASAN_HAS_EXCEPTIONS
 # define ASAN_HAS_EXCEPTIONS 1
 #endif
 
 // If set, values like allocator chunk size, as well as defaults for some flags
 // will be changed towards less memory overhead.
 #ifndef ASAN_LOW_MEMORY
-# if SANITIZER_IOS || (SANITIZER_WORDSIZE == 32)
+# if SANITIZER_IOS || SANITIZER_ANDROID
 #  define ASAN_LOW_MEMORY 1
 # else
 #  define ASAN_LOW_MEMORY 0
 # endif
 #endif
 
 #ifndef ASAN_DYNAMIC
 # ifdef PIC