[cfe-commits] r94939 - in /cfe/trunk: lib/CodeGen/CGClass.cpp test/CodeGenCXX/derived-to-base.cpp

[Anders Carlsson]

Author: andersca
Date: Sat Jan 30 19:43:37 2010
New Revision: 94939

URL: http://llvm.org/viewvc/llvm-project?rev=94939&view=rev
Log:
When doing a base-to-derived cast we don't need to null check the derived value if the class offset is 0.

Modified:
    cfe/trunk/lib/CodeGen/CGClass.cpp
    cfe/trunk/test/CodeGenCXX/derived-to-base.cpp

Modified: cfe/trunk/lib/CodeGen/CGClass.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGClass.cpp?rev=94939&r1=94938&r2=94939&view=diff

==============================================================================
--- cfe/trunk/lib/CodeGen/CGClass.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGClass.cpp Sat Jan 30 19:43:37 2010
@@ -224,6 +224,14 @@
     return Builder.CreateBitCast(Value, DerivedPtrTy);
   }
 
+  llvm::Value *NonVirtualOffset =
+    CGM.GetNonVirtualBaseClassOffset(DerivedClass, Class);
+  
+  if (!NonVirtualOffset) {
+    // No offset, we can just cast back.
+    return Builder.CreateBitCast(Value, DerivedPtrTy);
+  }
+  
   llvm::BasicBlock *CastNull = 0;
   llvm::BasicBlock *CastNotNull = 0;
   llvm::BasicBlock *CastEnd = 0;
@@ -240,16 +248,13 @@
     EmitBlock(CastNotNull);
   }
   
-  if (llvm::Value *NonVirtualOffset =
-      CGM.GetNonVirtualBaseClassOffset(DerivedClass, Class)) {
-    // Apply the offset.
-    Value = Builder.CreatePtrToInt(Value, NonVirtualOffset->getType());
-    Value = Builder.CreateSub(Value, NonVirtualOffset);
-    Value = Builder.CreateIntToPtr(Value, DerivedPtrTy);
-  } else {
-    // Just cast.
-    Value = Builder.CreateBitCast(Value, DerivedPtrTy);
-  }
+  // Apply the offset.
+  Value = Builder.CreatePtrToInt(Value, NonVirtualOffset->getType());
+  Value = Builder.CreateSub(Value, NonVirtualOffset);
+  Value = Builder.CreateIntToPtr(Value, DerivedPtrTy);
+
+  // Just cast.
+  Value = Builder.CreateBitCast(Value, DerivedPtrTy);
 
   if (NullCheckValue) {
     Builder.CreateBr(CastEnd);

Modified: cfe/trunk/test/CodeGenCXX/derived-to-base.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/derived-to-base.cpp?rev=94939&r1=94938&r2=94939&view=diff

==============================================================================
--- cfe/trunk/test/CodeGenCXX/derived-to-base.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/derived-to-base.cpp Sat Jan 30 19:43:37 2010
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -emit-llvm %s -o -
+// RUN: %clang_cc1 %s -triple=x86_64-apple-darwin10 -emit-llvm -o - | FileCheck %s
 struct A { 
   void f(); 
   
@@ -14,3 +14,10 @@
   
   b.f();
 }
+
+// CHECK: define %struct.B* @_Z1fP1A(%struct.A* %a) nounwind
+B *f(A *a) {
+  // CHECK-NOT: br label
+  // CHECK: ret %struct.B*
+  return static_cast<B*>(a);
+}