[cfe-commits] r90820 - in /cfe/trunk: lib/CodeGen/CGRecordLayoutBuilder.cpp test/CodeGenCXX/class-layout.cpp

[Anders Carlsson]

Author: andersca
Date: Mon Dec  7 19:24:23 2009
New Revision: 90820

URL: http://llvm.org/viewvc/llvm-project?rev=90820&view=rev
Log:
No need to add tail padding if the resulting LLVM struct type will have the same size as the final record size.

Modified:
    cfe/trunk/lib/CodeGen/CGRecordLayoutBuilder.cpp
    cfe/trunk/test/CodeGenCXX/class-layout.cpp

Modified: cfe/trunk/lib/CodeGen/CGRecordLayoutBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGRecordLayoutBuilder.cpp?rev=90820&r1=90819&r2=90820&view=diff

==============================================================================
--- cfe/trunk/lib/CodeGen/CGRecordLayoutBuilder.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGRecordLayoutBuilder.cpp Mon Dec  7 19:24:23 2009
@@ -88,8 +88,6 @@
 
   AppendBytes(NumBytesToAppend);
 
-  AlignmentAsLLVMStruct = std::max(AlignmentAsLLVMStruct, getTypeAlignment(Ty));
-
   BitsAvailableInLastField =
     NextFieldOffsetInBytes * 8 - (FieldOffset + FieldSize);
 }
@@ -247,6 +245,14 @@
   uint64_t RecordSizeInBytes = RecordSize / 8;
   assert(NextFieldOffsetInBytes <= RecordSizeInBytes && "Size mismatch!");
 
+  uint64_t AlignedNextFieldOffset = 
+    llvm::RoundUpToAlignment(NextFieldOffsetInBytes, AlignmentAsLLVMStruct);
+
+  if (AlignedNextFieldOffset == RecordSizeInBytes) {
+    // We don't need any padding.
+    return;
+  }
+  
   unsigned NumPadBytes = RecordSizeInBytes - NextFieldOffsetInBytes;
   AppendBytes(NumPadBytes);
 }

Modified: cfe/trunk/test/CodeGenCXX/class-layout.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/class-layout.cpp?rev=90820&r1=90819&r2=90820&view=diff

==============================================================================
--- cfe/trunk/test/CodeGenCXX/class-layout.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/class-layout.cpp Mon Dec  7 19:24:23 2009
@@ -1,5 +1,9 @@
-// RUN: clang-cc %s -emit-llvm -o %t
+// RUN: clang-cc %s -emit-llvm -o - | FileCheck %s
 
 // An extra byte shoudl be allocated for an empty class.
-// RUN: grep '%.truct.A = type { i8 }' %t
+// CHECK: %struct.A = type { i8 }
 struct A { } a;
+
+// No need to add tail padding here.
+// CHECK: %struct.B = type { i8*, i32 }
+struct B { void *a; int b; } b;