Teach SCEVExpander::InsertCastOfTo to avoid creating inttoptr-of-ptrtoint

and ptrtoint-of-inttoptr expressions. This fixes a regression in 300.twolf.

llvm-svn: 69293

2 files changed, 10 insertions, 2 deletions

diff --git a/llvm/include/llvm/Analysis/ScalarEvolutionExpander.h b/llvm/include/llvm/Analysis/ScalarEvolutionExpander.h
index 8126a589a45..2f660c9c5b3 100644
--- a/llvm/include/llvm/Analysis/ScalarEvolutionExpander.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolutionExpander.h
@@ -83,8 +83,8 @@ namespace llvm {
 
     /// InsertCastOfTo - Insert a cast of V to the specified type, doing what
     /// we can to share the casts.
-    static Value *InsertCastOfTo(Instruction::CastOps opcode, Value *V, 
-                                 const Type *Ty);
+    Value *InsertCastOfTo(Instruction::CastOps opcode, Value *V,
+                          const Type *Ty);
     /// InsertBinop - Insert the specified binary operator, doing a small amount
     /// of work to avoid inserting an obviously redundant operation.
     static Value *InsertBinop(Instruction::BinaryOps Opcode, Value *LHS,
diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
index d91061b2b3a..0033fb4ae4a 100644
--- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -26,6 +26,14 @@ Value *SCEVExpander::InsertCastOfTo(Instruction::CastOps opcode, Value *V,
   if (opcode == Instruction::BitCast && V->getType() == Ty)
     return V;
 
+  // Short-circuit unnecessary inttoptr<->ptrtoint casts.
+  if (opcode == Instruction::PtrToInt && Ty == TD.getIntPtrType())
+    if (IntToPtrInst *ITP = dyn_cast<IntToPtrInst>(V))
+      return ITP->getOperand(0);
+  if (opcode == Instruction::IntToPtr && V->getType() == TD.getIntPtrType())
+    if (PtrToIntInst *PTI = dyn_cast<PtrToIntInst>(V))
+      return PTI->getOperand(0);
+
   // FIXME: keep track of the cast instruction.
   if (Constant *C = dyn_cast<Constant>(V))
     return ConstantExpr::getCast(opcode, C, Ty);