From: David Majnemer <david.majnemer@gmail.com>
Date: Tue, 17 Nov 2015 08:15:14 +0000 (+0000)
Subject: [AliasAnalysis] CatchPad and CatchRet can modify escaped memory
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=bef6034cc2b3c10c7762d8aa7831bf4b44d56854

[AliasAnalysis] CatchPad and CatchRet can modify escaped memory

CatchPad and CatchRet behave a lot like function calls: they can
potentially modify any memory which has been escaped.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253323 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/Analysis/AliasAnalysis.h b/include/llvm/Analysis/AliasAnalysis.h
index 2f4722fb964..5cc840a64a6 100644
--- a/include/llvm/Analysis/AliasAnalysis.h
+++ b/include/llvm/Analysis/AliasAnalysis.h
@@ -421,6 +421,26 @@ public:
     return getModRefInfo(I, MemoryLocation(P, Size));
   }
 
+  /// getModRefInfo (for catchpads) - Return information about whether
+  /// a particular catchpad modifies or reads the specified memory location.
+  ModRefInfo getModRefInfo(const CatchPadInst *I, const MemoryLocation &Loc);
+
+  /// getModRefInfo (for catchpads) - A convenience wrapper.
+  ModRefInfo getModRefInfo(const CatchPadInst *I, const Value *P,
+                           uint64_t Size) {
+    return getModRefInfo(I, MemoryLocation(P, Size));
+  }
+
+  /// getModRefInfo (for catchrets) - Return information about whether
+  /// a particular catchret modifies or reads the specified memory location.
+  ModRefInfo getModRefInfo(const CatchReturnInst *I, const MemoryLocation &Loc);
+
+  /// getModRefInfo (for catchrets) - A convenience wrapper.
+  ModRefInfo getModRefInfo(const CatchReturnInst *I, const Value *P,
+                           uint64_t Size) {
+    return getModRefInfo(I, MemoryLocation(P, Size));
+  }
+
   /// Check whether or not an instruction may read or write memory (without
   /// regard to a specific location).
   ///
@@ -461,6 +481,10 @@ public:
       return getModRefInfo((const AtomicRMWInst*)I, Loc);
     case Instruction::Call:   return getModRefInfo((const CallInst*)I,  Loc);
     case Instruction::Invoke: return getModRefInfo((const InvokeInst*)I,Loc);
+    case Instruction::CatchPad:
+      return getModRefInfo((const CatchPadInst *)I, Loc);
+    case Instruction::CatchRet:
+      return getModRefInfo((const CatchReturnInst *)I, Loc);
     default:
       return MRI_NoModRef;
     }
diff --git a/lib/Analysis/AliasAnalysis.cpp b/lib/Analysis/AliasAnalysis.cpp
index 0fef5c66651..35f2e97622f 100644
--- a/lib/Analysis/AliasAnalysis.cpp
+++ b/lib/Analysis/AliasAnalysis.cpp
@@ -247,6 +247,32 @@ ModRefInfo AAResults::getModRefInfo(const VAArgInst *V,
   return MRI_ModRef;
 }
 
+ModRefInfo AAResults::getModRefInfo(const CatchPadInst *CatchPad,
+                                    const MemoryLocation &Loc) {
+  if (Loc.Ptr) {
+    // If the pointer is a pointer to constant memory,
+    // then it could not have been modified by this catchpad.
+    if (pointsToConstantMemory(Loc))
+      return MRI_NoModRef;
+  }
+
+  // Otherwise, a catchpad reads and writes.
+  return MRI_ModRef;
+}
+
+ModRefInfo AAResults::getModRefInfo(const CatchReturnInst *CatchRet,
+                                    const MemoryLocation &Loc) {
+  if (Loc.Ptr) {
+    // If the pointer is a pointer to constant memory,
+    // then it could not have been modified by this catchpad.
+    if (pointsToConstantMemory(Loc))
+      return MRI_NoModRef;
+  }
+
+  // Otherwise, a catchret reads and writes.
+  return MRI_ModRef;
+}
+
 ModRefInfo AAResults::getModRefInfo(const AtomicCmpXchgInst *CX,
                                     const MemoryLocation &Loc) {
   // Acquire/Release cmpxchg has properties that matter for arbitrary addresses.