From: Duncan Sands <baldrick@free.fr>
Date: Tue, 30 Oct 2012 16:03:32 +0000 (+0000)
Subject: Fix isEliminableCastPair to work correctly in the presence of pointers
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=446cf94cdbbc1f8e22452fc46664ac73d810c6a2;p=oota-llvm.git

Fix isEliminableCastPair to work correctly in the presence of pointers
with different sizes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167018 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/InstrTypes.h b/include/llvm/InstrTypes.h
index b661372f53b..74e51ffa0fb 100644
--- a/include/llvm/InstrTypes.h
+++ b/include/llvm/InstrTypes.h
@@ -594,7 +594,9 @@ public:
     Type *SrcTy, ///< SrcTy of 1st cast
     Type *MidTy, ///< DstTy of 1st cast & SrcTy of 2nd cast
     Type *DstTy, ///< DstTy of 2nd cast
-    Type *IntPtrTy ///< Integer type corresponding to Ptr types, or null
+    Type *SrcIntPtrTy, ///< Integer type corresponding to Ptr SrcTy, or null
+    Type *MidIntPtrTy, ///< Integer type corresponding to Ptr MidTy, or null
+    Type *DstIntPtrTy  ///< Integer type corresponding to Ptr DstTy, or null
   );
 
   /// @brief Return the opcode of this CastInst
diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 119d2f5c99d..1807bea2352 100644
--- a/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -238,16 +238,20 @@ isEliminableCastPair(
   // Get the opcodes of the two Cast instructions
   Instruction::CastOps firstOp = Instruction::CastOps(CI->getOpcode());
   Instruction::CastOps secondOp = Instruction::CastOps(opcode);
+  Type *SrcIntPtrTy = TD && SrcTy->isPtrOrPtrVectorTy() ?
+    TD->getIntPtrType(SrcTy) : 0;
+  Type *MidIntPtrTy = TD && MidTy->isPtrOrPtrVectorTy() ?
+    TD->getIntPtrType(MidTy) : 0;
+  Type *DstIntPtrTy = TD && DstTy->isPtrOrPtrVectorTy() ?
+    TD->getIntPtrType(DstTy) : 0;
   unsigned Res = CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy,
-                                                DstTy,
-                                  TD ? TD->getIntPtrType(DstTy) : 0);
+                                                DstTy, SrcIntPtrTy, MidIntPtrTy,
+                                                DstIntPtrTy);
 
   // We don't want to form an inttoptr or ptrtoint that converts to an integer
   // type that differs from the pointer size.
-  if ((Res == Instruction::IntToPtr &&
-          (!TD || SrcTy != TD->getIntPtrType(DstTy))) ||
-      (Res == Instruction::PtrToInt &&
-          (!TD || DstTy != TD->getIntPtrType(SrcTy))))
+  if ((Res == Instruction::IntToPtr && SrcTy != DstIntPtrTy) ||
+      (Res == Instruction::PtrToInt && DstTy != SrcIntPtrTy))
     Res = 0;
 
   return Instruction::CastOps(Res);
diff --git a/lib/VMCore/ConstantFold.cpp b/lib/VMCore/ConstantFold.cpp
index 60cd3fbe22d..fe3edac42e7 100644
--- a/lib/VMCore/ConstantFold.cpp
+++ b/lib/VMCore/ConstantFold.cpp
@@ -87,9 +87,13 @@ foldConstantCastPair(
   Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
   Instruction::CastOps secondOp = Instruction::CastOps(opc);
 
+  // Assume that pointers are never more than 64 bits wide.
+  IntegerType *FakeIntPtrTy = Type::getInt64Ty(DstTy->getContext());
+
   // Let CastInst::isEliminableCastPair do the heavy lifting.
   return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
-                                        Type::getInt64Ty(DstTy->getContext()));
+                                        FakeIntPtrTy, FakeIntPtrTy,
+                                        FakeIntPtrTy);
 }
 
 static Constant *FoldBitCast(Constant *V, Type *DestTy) {
diff --git a/lib/VMCore/Instructions.cpp b/lib/VMCore/Instructions.cpp
index e9b96d6cd22..39ba4df15b4 100644
--- a/lib/VMCore/Instructions.cpp
+++ b/lib/VMCore/Instructions.cpp
@@ -2141,7 +2141,8 @@ bool CastInst::isNoopCast(const DataLayout &DL) const {
 /// If no such cast is permited, the function returns 0.
 unsigned CastInst::isEliminableCastPair(
   Instruction::CastOps firstOp, Instruction::CastOps secondOp,
-  Type *SrcTy, Type *MidTy, Type *DstTy, Type *IntPtrTy) {
+  Type *SrcTy, Type *MidTy, Type *DstTy, Type *SrcIntPtrTy, Type *MidIntPtrTy,
+  Type *DstIntPtrTy) {
   // Define the 144 possibilities for these two cast instructions. The values
   // in this matrix determine what to do in a given situation and select the
   // case in the switch below.  The rows correspond to firstOp, the columns 
@@ -2244,9 +2245,9 @@ unsigned CastInst::isEliminableCastPair(
       return 0;
     case 7: { 
       // ptrtoint, inttoptr -> bitcast (ptr -> ptr) if int size is >= ptr size
-      if (!IntPtrTy)
+      if (!SrcIntPtrTy || DstIntPtrTy != SrcIntPtrTy)
         return 0;
-      unsigned PtrSize = IntPtrTy->getScalarSizeInBits();
+      unsigned PtrSize = SrcIntPtrTy->getScalarSizeInBits();
       unsigned MidSize = MidTy->getScalarSizeInBits();
       if (MidSize >= PtrSize)
         return Instruction::BitCast;
@@ -2285,9 +2286,9 @@ unsigned CastInst::isEliminableCastPair(
       return 0;
     case 13: {
       // inttoptr, ptrtoint -> bitcast if SrcSize<=PtrSize and SrcSize==DstSize
-      if (!IntPtrTy)
+      if (!MidIntPtrTy)
         return 0;
-      unsigned PtrSize = IntPtrTy->getScalarSizeInBits();
+      unsigned PtrSize = MidIntPtrTy->getScalarSizeInBits();
       unsigned SrcSize = SrcTy->getScalarSizeInBits();
       unsigned DstSize = DstTy->getScalarSizeInBits();
       if (SrcSize <= PtrSize && SrcSize == DstSize)
diff --git a/unittests/VMCore/InstructionsTest.cpp b/unittests/VMCore/InstructionsTest.cpp
index 4cadc36f8f0..a3b13ce92d1 100644
--- a/unittests/VMCore/InstructionsTest.cpp
+++ b/unittests/VMCore/InstructionsTest.cpp
@@ -243,5 +243,42 @@ TEST(InstructionsTest, FPMathOperator) {
   delete I;
 }
 
+
+TEST(InstructionsTest, isEliminableCastPair) {
+  LLVMContext &C(getGlobalContext());
+
+  Type* Int32Ty = Type::getInt32Ty(C);
+  Type* Int64Ty = Type::getInt64Ty(C);
+  Type* Int64PtrTy = Type::getInt64PtrTy(C);
+
+  // Source and destination pointers have same size -> bitcast.
+  EXPECT_EQ(CastInst::isEliminableCastPair(CastInst::PtrToInt,
+                                           CastInst::IntToPtr,
+                                           Int64PtrTy, Int64Ty, Int64PtrTy,
+                                           Int32Ty, 0, Int32Ty),
+            CastInst::BitCast);
+
+  // Source and destination pointers have different sizes -> fail.
+  EXPECT_EQ(CastInst::isEliminableCastPair(CastInst::PtrToInt,
+                                           CastInst::IntToPtr,
+                                           Int64PtrTy, Int64Ty, Int64PtrTy,
+                                           Int32Ty, 0, Int64Ty),
+            0U);
+
+  // Middle pointer big enough -> bitcast.
+  EXPECT_EQ(CastInst::isEliminableCastPair(CastInst::IntToPtr,
+                                           CastInst::PtrToInt,
+                                           Int64Ty, Int64PtrTy, Int64Ty,
+                                           0, Int64Ty, 0),
+            CastInst::BitCast);
+
+  // Middle pointer too small -> fail.
+  EXPECT_EQ(CastInst::isEliminableCastPair(CastInst::IntToPtr,
+                                           CastInst::PtrToInt,
+                                           Int64Ty, Int64PtrTy, Int64Ty,
+                                           0, Int32Ty, 0),
+            0U);
+}
+
 }  // end anonymous namespace
 }  // end namespace llvm