From: Eli Friedman <eli.friedman@gmail.com>
Date: Tue, 28 Feb 2012 22:07:56 +0000 (+0000)
Subject: Prefer bitcast+GEP over ptrtoint+sub+inttoptr: it's semantically equivalent here... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c5685438df6105052b02c9e02f01c34489606308;p=clang

Prefer bitcast+GEP over ptrtoint+sub+inttoptr: it's semantically equivalent here, and generally nicer to the optimizer.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151659 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CGClass.cpp b/lib/CodeGen/CGClass.cpp
index b9abbf2901..e3b5777387 100644
--- a/lib/CodeGen/CGClass.cpp
+++ b/lib/CodeGen/CGClass.cpp
@@ -249,9 +249,9 @@ CodeGenFunction::GetAddressOfDerivedClass(llvm::Value *Value,
   }
   
   // Apply the offset.
-  Value = Builder.CreatePtrToInt(Value, NonVirtualOffset->getType());
-  Value = Builder.CreateSub(Value, NonVirtualOffset);
-  Value = Builder.CreateIntToPtr(Value, DerivedPtrTy);
+  Value = Builder.CreateBitCast(Value, Int8PtrTy);
+  Value = Builder.CreateGEP(Value, Builder.CreateNeg(NonVirtualOffset),
+                            "sub.ptr");
 
   // Just cast.
   Value = Builder.CreateBitCast(Value, DerivedPtrTy);