[PATCH] D81367: [ASan][NFC] Refactor redzone size calculation

[Marco Elver via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG8af7fa07aa24: [ASan][NFC] Refactor redzone size calculation (authored by melver).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D81367/new/

https://reviews.llvm.org/D81367

Files:
  llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp


Index: llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -537,7 +537,7 @@
   return Mapping;
 }
 
-static size_t RedzoneSizeForScale(int MappingScale) {
+static uint64_t getRedzoneSizeForScale(int MappingScale) {
   // Redzone used for stack and globals is at least 32 bytes.
   // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
   return std::max(32U, 1U << MappingScale);
@@ -797,9 +797,10 @@
   StringRef getGlobalMetadataSection() const;
   void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
   void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
-  size_t MinRedzoneSizeForGlobal() const {
-    return RedzoneSizeForScale(Mapping.Scale);
+  uint64_t getMinRedzoneSizeForGlobal() const {
+    return getRedzoneSizeForScale(Mapping.Scale);
   }
+  uint64_t getRedzoneSizeForGlobal(uint64_t SizeInBytes) const;
   int GetAsanVersion(const Module &M) const;
 
   const GlobalsMetadata &GlobalsMD;
@@ -1824,7 +1825,7 @@
   //   - Need to poison all copies, not just the main thread's one.
   if (G->isThreadLocal()) return false;
   // For now, just ignore this Global if the alignment is large.
-  if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
+  if (G->getAlignment() > getMinRedzoneSizeForGlobal()) return false;
 
   // For non-COFF targets, only instrument globals known to be defined by this
   // TU.
@@ -2312,7 +2313,6 @@
       M, M.getModuleIdentifier(), /*AllowMerging*/ false, kAsanGenPrefix);
 
   for (size_t i = 0; i < n; i++) {
-    static const uint64_t kMaxGlobalRedzone = 1 << 18;
     GlobalVariable *G = GlobalsToChange[i];
 
     // FIXME: Metadata should be attched directly to the global directly instead
@@ -2326,16 +2326,8 @@
         /*AllowMerging*/ true, kAsanGenPrefix);
 
     Type *Ty = G->getValueType();
-    uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
-    uint64_t MinRZ = MinRedzoneSizeForGlobal();
-    // MinRZ <= RZ <= kMaxGlobalRedzone
-    // and trying to make RZ to be ~ 1/4 of SizeInBytes.
-    uint64_t RZ = std::max(
-        MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
-    uint64_t RightRedzoneSize = RZ;
-    // Round up to MinRZ
-    if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
-    assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
+    const uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
+    const uint64_t RightRedzoneSize = getRedzoneSizeForGlobal(SizeInBytes);
     Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
 
     StructType *NewTy = StructType::get(Ty, RightRedZoneTy);
@@ -2351,7 +2343,7 @@
                            "", G, G->getThreadLocalMode());
     NewGlobal->copyAttributesFrom(G);
     NewGlobal->setComdat(G->getComdat());
-    NewGlobal->setAlignment(MaybeAlign(MinRZ));
+    NewGlobal->setAlignment(MaybeAlign(getMinRedzoneSizeForGlobal()));
     // Don't fold globals with redzones. ODR violation detector and redzone
     // poisoning implicitly creates a dependence on the global's address, so it
     // is no longer valid for it to be marked unnamed_addr.
@@ -2473,6 +2465,23 @@
   return true;
 }
 
+uint64_t
+ModuleAddressSanitizer::getRedzoneSizeForGlobal(uint64_t SizeInBytes) const {
+  constexpr uint64_t kMaxRZ = 1 << 18;
+  const uint64_t MinRZ = getMinRedzoneSizeForGlobal();
+
+  // Calculate RZ, where MinRZ <= RZ <= MaxRZ, and RZ ~ 1/4 * SizeInBytes.
+  uint64_t RZ =
+      std::max(MinRZ, std::min(kMaxRZ, (SizeInBytes / MinRZ / 4) * MinRZ));
+
+  // Round up to multiple of MinRZ.
+  if (SizeInBytes % MinRZ)
+    RZ += MinRZ - (SizeInBytes % MinRZ);
+  assert((RZ + SizeInBytes) % MinRZ == 0);
+
+  return RZ;
+}
+
 int ModuleAddressSanitizer::GetAsanVersion(const Module &M) const {
   int LongSize = M.getDataLayout().getPointerSizeInBits();
   bool isAndroid = Triple(M.getTargetTriple()).isAndroid();


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