1 files changed, 26 insertions, 1 deletions
diff --git a/contrib/llvm-project/llvm/lib/Analysis/AliasAnalysis.cpp b/contrib/llvm-project/llvm/lib/Analysis/AliasAnalysis.cpp
index 7b2f91f5392a..da18279ae9b9 100644
--- a/contrib/llvm-project/llvm/lib/Analysis/AliasAnalysis.cpp
+++ b/contrib/llvm-project/llvm/lib/Analysis/AliasAnalysis.cpp
@@ -896,7 +896,7 @@ bool llvm::isNotVisibleOnUnwind(const Value *Object,
 
   // Byval goes out of scope on unwind.
   if (auto *A = dyn_cast<Argument>(Object))
-    return A->hasByValAttr();
+    return A->hasByValAttr() || A->hasAttribute(Attribute::DeadOnUnwind);
 
   // A noalias return is not accessible from any other code. If the pointer
   // does not escape prior to the unwind, then the caller cannot access the
@@ -908,3 +908,28 @@ bool llvm::isNotVisibleOnUnwind(const Value *Object,
 
   return false;
 }
+
+// We don't consider globals as writable: While the physical memory is writable,
+// we may not have provenance to perform the write.
+bool llvm::isWritableObject(const Value *Object,
+                            bool &ExplicitlyDereferenceableOnly) {
+  ExplicitlyDereferenceableOnly = false;
+
+  // TODO: Alloca might not be writable after its lifetime ends.
+  // See https://github.com/llvm/llvm-project/issues/51838.
+  if (isa<AllocaInst>(Object))
+    return true;
+
+  if (auto *A = dyn_cast<Argument>(Object)) {
+    if (A->hasAttribute(Attribute::Writable)) {
+      ExplicitlyDereferenceableOnly = true;
+      return true;
+    }
+
+    return A->hasByValAttr();
+  }
+
+  // TODO: Noalias shouldn't imply writability, this should check for an
+  // allocator function instead.
+  return isNoAliasCall(Object);
+}