Revert "[scudo] Small cleanup of memory tagging code. (#166860)"

This reverts commit 046ae85.

Author: cferris1000

compiler-rt/lib/scudo/standalone/combined.h

@@ -171,7 +171,8 @@ class Allocator {
       Primary.Options.set(OptionBit::DeallocTypeMismatch);
     if (getFlags()->delete_size_mismatch)
       Primary.Options.set(OptionBit::DeleteSizeMismatch);
-    if (systemSupportsMemoryTagging())
+    if (allocatorSupportsMemoryTagging<AllocatorConfig>() &&
+        systemSupportsMemoryTagging())
       Primary.Options.set(OptionBit::UseMemoryTagging);
 
     QuarantineMaxChunkSize =

compiler-rt/lib/scudo/standalone/memtag.h

@@ -66,8 +66,7 @@ inline bool systemSupportsMemoryTagging() {
 #ifndef HWCAP2_MTE
 #define HWCAP2_MTE (1 << 18)
 #endif
-  static bool SupportsMemoryTagging = getauxval(AT_HWCAP2) & HWCAP2_MTE;
-  return SupportsMemoryTagging;
+  return getauxval(AT_HWCAP2) & HWCAP2_MTE;
 }
 
 inline bool systemDetectsMemoryTagFaultsTestOnly() {
@@ -262,7 +261,9 @@ inline uptr loadTag(uptr Ptr) {
 
 #else
 
-inline bool systemSupportsMemoryTagging() { return false; }
+inline NORETURN bool systemSupportsMemoryTagging() {
+  UNREACHABLE("memory tagging not supported");
+}
 
 inline NORETURN bool systemDetectsMemoryTagFaultsTestOnly() {
   UNREACHABLE("memory tagging not supported");

compiler-rt/lib/scudo/standalone/tests/memtag_test.cpp

@@ -28,6 +28,7 @@ TEST(MemtagBasicDeathTest, Unsupported) {
   EXPECT_DEATH(untagPointer((uptr)0), "not supported");
   EXPECT_DEATH(extractTag((uptr)0), "not supported");
 
+  EXPECT_DEATH(systemSupportsMemoryTagging(), "not supported");
   EXPECT_DEATH(systemDetectsMemoryTagFaultsTestOnly(), "not supported");
   EXPECT_DEATH(enableSystemMemoryTaggingTestOnly(), "not supported");
 

compiler-rt/lib/scudo/standalone/tests/secondary_test.cpp

@@ -27,7 +27,9 @@
 const scudo::uptr PageSize = scudo::getPageSizeCached();
 
 template <typename Config> static scudo::Options getOptionsForConfig() {
-  if (!scudo::systemSupportsMemoryTagging())
+  if (!Config::getMaySupportMemoryTagging() ||
+      !scudo::archSupportsMemoryTagging() ||
+      !scudo::systemSupportsMemoryTagging())
     return {};
   scudo::AtomicOptions AO;
   AO.set(scudo::OptionBit::UseMemoryTagging);

compiler-rt/lib/scudo/standalone/tests/wrappers_cpp_test.cpp

@@ -187,7 +187,8 @@ TEST_F(ScudoWrappersCppTest, ThreadedNew) {
   // TODO: Investigate why libc sometimes crashes with tag missmatch in
   // __pthread_clockjoin_ex.
   std::unique_ptr<scudo::ScopedDisableMemoryTagChecks> NoTags;
-  if (!SCUDO_ANDROID && scudo::systemSupportsMemoryTagging())
+  if (!SCUDO_ANDROID && scudo::archSupportsMemoryTagging() &&
+      scudo::systemSupportsMemoryTagging())
     NoTags = std::make_unique<scudo::ScopedDisableMemoryTagChecks>();
 
   Ready = false;