Consider addrspaces in canLosslesslyBitCastTo()

Make this conservatively correct and report false for different
address spaces, which might require a nontrivial translation.

Based on the few uses of this, I don't think this currently
breaks anything.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216846 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/IR/Type.cpp b/lib/IR/Type.cpp
index ae7af8f..90fde4d 100644 (file)
--- a/lib/IR/Type.cpp
+++ b/lib/IR/Type.cpp
@@ -89,9 +89,13 @@ bool Type::canLosslesslyBitCastTo(Type *Ty) const {
 
   // At this point we have only various mismatches of the first class types
   // remaining and ptr->ptr. Just select the lossless conversions. Everything
-  // else is not lossless.
-  if (this->isPointerTy())
-    return Ty->isPointerTy();
+  // else is not lossless. Conservatively assume we can't losslessly convert
+  // between pointers with different address spaces.
+  if (const PointerType *PTy = dyn_cast<PointerType>(this)) {
+    if (const PointerType *OtherPTy = dyn_cast<PointerType>(Ty))
+      return PTy->getAddressSpace() == OtherPTy->getAddressSpace();
+    return false;
+  }
   return false;  // Other types have no identity values
 }