Revert "[ASan] Removed ASAN_SHADOW_SCALE."

[kstoimenov]

Summary

This reverts commit e4800fc099ad204f88c432276e6488772042bffc.

[MaskRay]

A revert needs a description why it was made so that people doing archaeology would have better idea what happened.
For this case they would be curious why the change was brought back.

[kstoimenov]

Got it. Will provide revert description next time. In this case it was a build failure caused by bad merge.

[MaskRay]

In D115286#3177954, @kstoimenov wrote:

Got it. Will provide revert description next time. In this case it was a build failure caused by bad merge.

Thanks:) Such reverts (to fix a build failure, you are the original author/reviewer, committed recently) don't need a revision. You could just push the commit :)

compiler-rt/CMakeLists.txt

 mark_as_advanced(COMPILER_RT_BUILD_MEMPROF)
 option(COMPILER_RT_BUILD_XRAY_NO_PREINIT "Build xray with no preinit patching" OFF)
 mark_as_advanced(COMPILER_RT_BUILD_XRAY_NO_PREINIT)
 option(COMPILER_RT_BUILD_ORC "Build ORC runtime" ON)
 mark_as_advanced(COMPILER_RT_BUILD_ORC)
 option(COMPILER_RT_BUILD_GWP_ASAN "Build GWP-ASan, and link it into SCUDO" ON)
 mark_as_advanced(COMPILER_RT_BUILD_GWP_ASAN)
 
+set(COMPILER_RT_ASAN_SHADOW_SCALE ""
+    CACHE STRING "Override the shadow scale to be used in ASan runtime")
+
+if (NOT COMPILER_RT_ASAN_SHADOW_SCALE STREQUAL "")
+  # Check that the shadow scale value is valid.
+  if (NOT (COMPILER_RT_ASAN_SHADOW_SCALE GREATER -1 AND
+           COMPILER_RT_ASAN_SHADOW_SCALE LESS 8))
+    message(FATAL_ERROR "
+      Invalid ASan Shadow Scale '${COMPILER_RT_ASAN_SHADOW_SCALE}'.")
+  endif()
+
+  set(COMPILER_RT_ASAN_SHADOW_SCALE_LLVM_FLAG
+      -mllvm -asan-mapping-scale=${COMPILER_RT_ASAN_SHADOW_SCALE})
+  set(COMPILER_RT_ASAN_SHADOW_SCALE_DEFINITION
+      ASAN_SHADOW_SCALE=${COMPILER_RT_ASAN_SHADOW_SCALE})
+  set(COMPILER_RT_ASAN_SHADOW_SCALE_FLAG
+      -D${COMPILER_RT_ASAN_SHADOW_SCALE_DEFINITION})
+endif()
+
 if(FUCHSIA)
   set(COMPILER_RT_HWASAN_WITH_INTERCEPTORS_DEFAULT OFF)
 else()
   set(COMPILER_RT_HWASAN_WITH_INTERCEPTORS_DEFAULT ON)
 endif()
 set(COMPILER_RT_HWASAN_WITH_INTERCEPTORS ${COMPILER_RT_HWASAN_WITH_INTERCEPTORS_DEFAULT} CACHE BOOL "Enable libc interceptors in HWASan (testing mode)")
 
 set(COMPILER_RT_BAREMETAL_BUILD OFF CACHE BOOL

compiler-rt/lib/asan/asan_mapping.h

 // (the exact location of HighShadow/HighMem may vary depending
 //  on WoW64, /LARGEADDRESSAWARE, etc).
 // || `[0x50000000, 0xffffffff]` || HighMem    ||
 // || `[0x3a000000, 0x4fffffff]` || HighShadow ||
 // || `[0x36000000, 0x39ffffff]` || ShadowGap  ||
 // || `[0x30000000, 0x35ffffff]` || LowShadow  ||
 // || `[0x00000000, 0x2fffffff]` || LowMem     ||
 
-#define SHADOW_SCALE 3
-
+#if defined(ASAN_SHADOW_SCALE)
+static const u64 kDefaultShadowScale = ASAN_SHADOW_SCALE;
+#else
+static const u64 kDefaultShadowScale = 3;
+#endif
 static const u64 kDefaultShadowSentinel = ~(uptr)0;
 
+#define SHADOW_SCALE kDefaultShadowScale
+
 #if SANITIZER_FUCHSIA
 #  define SHADOW_OFFSET_CONST (0)
 #elif SANITIZER_WORDSIZE == 32
 #  if SANITIZER_ANDROID
 #    define SHADOW_OFFSET_DYNAMIC
 #  elif defined(__mips__)
 #    define SHADOW_OFFSET_CONST 0x0aaa0000
 #  elif SANITIZER_FREEBSD

compiler-rt/lib/asan/tests/CMakeLists.txt

 set(ASAN_UNITTEST_HEADERS
   asan_mac_test.h
   asan_test_config.h
   asan_test_utils.h)
 
 set(ASAN_UNITTEST_COMMON_CFLAGS
   ${COMPILER_RT_UNITTEST_CFLAGS}
   ${COMPILER_RT_GTEST_CFLAGS}
+  ${COMPILER_RT_ASAN_SHADOW_SCALE_LLVM_FLAG}
   -I${COMPILER_RT_SOURCE_DIR}/include
   -I${COMPILER_RT_SOURCE_DIR}/lib
   -I${COMPILER_RT_SOURCE_DIR}/lib/asan
   -I${COMPILER_RT_SOURCE_DIR}/lib/sanitizer_common/tests
   -fno-rtti
   -O2
   -Wno-format
   -Werror=sign-compare)

 endif()
 if(MSVC)
   list(APPEND ASAN_UNITTEST_COMMON_CFLAGS -gcodeview)
 endif()
 list(APPEND ASAN_UNITTEST_COMMON_LINK_FLAGS -g)
 
 # Use -D instead of definitions to please custom compile command.
 list(APPEND ASAN_UNITTEST_COMMON_CFLAGS
+  ${COMPILER_RT_ASAN_SHADOW_SCALE_FLAG}
   -DASAN_HAS_IGNORELIST=1
   -DASAN_HAS_EXCEPTIONS=1
   -DASAN_UAR=0
   )
 
 if(APPLE)
   list(APPEND ASAN_UNITTEST_COMMON_CFLAGS ${DARWIN_osx_CFLAGS})
   list(APPEND ASAN_UNITTEST_COMMON_LINK_FLAGS ${DARWIN_osx_LINK_FLAGS})

compiler-rt/lib/asan/tests/asan_interface_test.cpp

 }
 
 #define GOOD_ACCESS(ptr, offset)  \
     EXPECT_FALSE(__asan_address_is_poisoned(ptr + offset))
 
 #define BAD_ACCESS(ptr, offset) \
     EXPECT_TRUE(__asan_address_is_poisoned(ptr + offset))
 
+#if !defined(ASAN_SHADOW_SCALE) || ASAN_SHADOW_SCALE == 3
 static const char* kUseAfterPoisonErrorMessage = "use-after-poison";
 
 TEST(AddressSanitizerInterface, SimplePoisonMemoryRegionTest) {
   char *array = Ident((char*)malloc(120));
   // poison array[40..80)
   __asan_poison_memory_region(array + 40, 40);
   GOOD_ACCESS(array, 39);
   GOOD_ACCESS(array, 80);
TEST(AddressSanitizerInterface, OverlappingPoisonMemoryRegionTest) {
   __asan_unpoison_memory_region(array + 24, 72);
   BAD_ACCESS(array, 23);
   GOOD_ACCESS(array, 24);
   GOOD_ACCESS(array, 60);
   GOOD_ACCESS(array, 95);
   BAD_ACCESS(array, 96);
   free(array);
 }
+#endif  // !defined(ASAN_SHADOW_SCALE) || ASAN_SHADOW_SCALE == 3
 
 TEST(AddressSanitizerInterface, PushAndPopWithPoisoningTest) {
   // Vector of capacity 20
   char *vec = Ident((char*)malloc(20));
   __asan_poison_memory_region(vec, 20);
   for (size_t i = 0; i < 7; i++) {
     // Simulate push_back.
     __asan_unpoison_memory_region(vec + i, 1);