[compiler-rt] [scudo] Add primary option to zero block on dealloc. (PR #142394)

[via llvm-commits]

================
@@ -1345,6 +1352,19 @@ class Allocator {
         BlockBegin = retagBlock(Options, TaggedPtr, Ptr, Header, Size, true);
       }
 
+#ifdef SCUDO_FUCHSIA
+      if (AllocatorConfig::getEnableZeroOnDealloc()) {
+        // Clearing the header and is incompatible with quarantine and tagging.
+        // Hence, it is fine to implement it only when quanrantine is bypassed.
+        DCHECK(!useMemoryTagging<AllocatorConfig>(Options));
+        uptr length = reinterpret_cast<uptr>(Ptr) + Size -
+                      reinterpret_cast<uptr>(BlockBegin);
+        if (length <= ZeroOnDeallocMaxSize) {
+          memset(BlockBegin, 0, length);
+        }
----------------
ChiaHungDuan wrote:

nit: simple single statement, https://llvm.org/docs/CodingStandards.html#don-t-use-braces-on-simple-single-statement-bodies-of-if-else-loop-statements

https://github.com/llvm/llvm-project/pull/142394