[LICM][AA] Move isWritableObject() to AA (NFC)

Move this helper from LICM to AA, so it can be reused.

1 files changed, 17 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/AliasAnalysis.cpp b/llvm/lib/Analysis/AliasAnalysis.cpp
index 7b2f91f..75fe68a8 100644
--- a/llvm/lib/Analysis/AliasAnalysis.cpp
+++ b/llvm/lib/Analysis/AliasAnalysis.cpp
@@ -908,3 +908,20 @@ 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) {
+  // 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;
+
+  // TODO: Also handle sret.
+  if (auto *A = dyn_cast<Argument>(Object))
+    return A->hasByValAttr();
+
+  // TODO: Noalias shouldn't imply writability, this should check for an
+  // allocator function instead.
+  return isNoAliasCall(Object);
+}