[compiler-rt] 0d45bbc - [scudo] Skip releaseToOSMaybe if there's no byte in freelist

[Chia-hung Duan via llvm-commits]

Author: Chia-hung Duan
Date: 2023-05-10T20:20:17Z
New Revision: 0d45bbcb6007f5c345bacd30f94d61f6d9dfebb2

URL: https://github.com/llvm/llvm-project/commit/0d45bbcb6007f5c345bacd30f94d61f6d9dfebb2
DIFF: https://github.com/llvm/llvm-project/commit/0d45bbcb6007f5c345bacd30f94d61f6d9dfebb2.diff

LOG: [scudo] Skip releaseToOSMaybe if there's no byte in freelist

In primary32, the unused region will have max/min region index with 0
value and it's an invalid index. Skip releaseToOSMaybe in both primary32
and primary64 even it's M_PURGE_ALL.

Differential Revision: https://reviews.llvm.org/D150243

Added: 
    

Modified: 
    compiler-rt/lib/scudo/standalone/primary32.h
    compiler-rt/lib/scudo/standalone/primary64.h

Removed: 
    


################################################################################
diff  --git a/compiler-rt/lib/scudo/standalone/primary32.h b/compiler-rt/lib/scudo/standalone/primary32.h
index 7ac8df9dd95e4..726db754f245e 100644
--- a/compiler-rt/lib/scudo/standalone/primary32.h
+++ b/compiler-rt/lib/scudo/standalone/primary32.h
@@ -737,6 +737,9 @@ template <typename Config> class SizeClassAllocator32 {
         Sci->AllocatedUser -
         (Sci->Stats.PoppedBlocks - Sci->Stats.PushedBlocks) * BlockSize;
 
+    if (UNLIKELY(BytesInFreeList == 0))
+      return 0;
+
     bool MaySkip = false;
 
     if (BytesInFreeList <= Sci->ReleaseInfo.BytesInFreeListAtLastCheckpoint) {

diff  --git a/compiler-rt/lib/scudo/standalone/primary64.h b/compiler-rt/lib/scudo/standalone/primary64.h
index b954b7c0bf2ae..39248376eaac7 100644
--- a/compiler-rt/lib/scudo/standalone/primary64.h
+++ b/compiler-rt/lib/scudo/standalone/primary64.h
@@ -845,6 +845,9 @@ template <typename Config> class SizeClassAllocator64 {
         Region->AllocatedUser -
         (Region->Stats.PoppedBlocks - Region->Stats.PushedBlocks) * BlockSize;
 
+    if (UNLIKELY(BytesInFreeList == 0))
+      return 0;
+
     bool MaySkip = false;
 
     // Always update `BytesInFreeListAtLastCheckpoint` with the smallest value