[PATCH] D156618: [IR] Fix a memory leak if Function::dropAllReferences() is followed by setHungoffOperand

[Liqiang Tao via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
taolq marked an inline comment as not done.
Closed by commit rG85ec68d69bca: [IR] Fix a memory leak if Function::dropAllReferences() is followed by… (authored by taolq).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D156618/new/

https://reviews.llvm.org/D156618

Files:
  llvm/include/llvm/IR/Function.h
  llvm/lib/IR/Function.cpp


Index: llvm/lib/IR/Function.cpp
===================================================================
--- llvm/lib/IR/Function.cpp
+++ llvm/lib/IR/Function.cpp
@@ -518,15 +518,7 @@
   Src.setValueSubclassData(Src.getSubclassDataFromValue() | (1 << 0));
 }
 
-// dropAllReferences() - This function causes all the subinstructions to "let
-// go" of all references that they are maintaining.  This allows one to
-// 'delete' a whole class at a time, even though there may be circular
-// references... first all references are dropped, and all use counts go to
-// zero.  Then everything is deleted for real.  Note that no operations are
-// valid on an object that has "dropped all references", except operator
-// delete.
-//
-void Function::dropAllReferences() {
+void Function::deleteBodyImpl(bool ShouldDrop) {
   setIsMaterializable(false);
 
   for (BasicBlock &BB : *this)
@@ -537,10 +529,18 @@
   while (!BasicBlocks.empty())
     BasicBlocks.begin()->eraseFromParent();
 
-  // Drop uses of any optional data (real or placeholder).
   if (getNumOperands()) {
-    User::dropAllReferences();
-    setNumHungOffUseOperands(0);
+    if (ShouldDrop) {
+      // Drop uses of any optional data (real or placeholder).
+      User::dropAllReferences();
+      setNumHungOffUseOperands(0);
+    } else {
+      // The code needs to match Function::allocHungoffUselist().
+      auto *CPN = ConstantPointerNull::get(PointerType::get(getContext(), 0));
+      Op<0>().set(CPN);
+      Op<1>().set(CPN);
+      Op<2>().set(CPN);
+    }
     setValueSubclassData(getSubclassDataFromValue() & ~0xe);
   }
 
Index: llvm/include/llvm/IR/Function.h
===================================================================
--- llvm/include/llvm/IR/Function.h
+++ llvm/include/llvm/IR/Function.h
@@ -116,6 +116,8 @@
 
   void clearArguments();
 
+  void deleteBodyImpl(bool ShouldDrop);
+
   /// Function ctor - If the (optional) Module argument is specified, the
   /// function is automatically inserted into the end of the function list for
   /// the module.
@@ -667,7 +669,7 @@
   /// the linkage to external.
   ///
   void deleteBody() {
-    dropAllReferences();
+    deleteBodyImpl(/*ShouldDrop=*/false);
     setLinkage(ExternalLinkage);
   }
 
@@ -882,7 +884,9 @@
   /// function, dropping all references deletes the entire body of the function,
   /// including any contained basic blocks.
   ///
-  void dropAllReferences();
+  void dropAllReferences() {
+    deleteBodyImpl(/*ShouldDrop=*/true);
+  }
 
   /// hasAddressTaken - returns true if there are any uses of this function
   /// other than direct calls or invokes to it, or blockaddress expressions.


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