r199172 - [ms-abi] Small Change to pack+alignment interaction.

[Warren Hunt]

Author: whunt
Date: Mon Jan 13 18:54:36 2014
New Revision: 199172

URL: http://llvm.org/viewvc/llvm-project?rev=199172&view=rev
Log:
[ms-abi] Small Change to pack+alignment interaction.

This patch makes a small behavioral change to the interaction between 
pack and alignment.  Specifically it makes __declspec(align()) on a 
field change that field's alignment without respect to pack but the 
alignment change to the record alignment as a whole still obeys pack.


Modified:
    cfe/trunk/lib/AST/RecordLayoutBuilder.cpp
    cfe/trunk/test/Layout/ms-x86-pack-and-align.cpp

Modified: cfe/trunk/lib/AST/RecordLayoutBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/RecordLayoutBuilder.cpp?rev=199172&r1=199171&r2=199172&view=diff
==============================================================================
--- cfe/trunk/lib/AST/RecordLayoutBuilder.cpp (original)
+++ cfe/trunk/lib/AST/RecordLayoutBuilder.cpp Mon Jan 13 18:54:36 2014
@@ -2186,6 +2186,9 @@ MicrosoftRecordLayoutBuilder::getAdjuste
         Context.getTypeInfoInChars(FD->getType());
     if (FD->isBitField() && FD->getMaxAlignment() != 0)
       Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
+    // Respect pragma pack.
+    if (!MaxFieldAlignment.isZero())
+      Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
   }
   // Respect packed field attribute.
   if (FD->hasAttr<PackedAttr>())
@@ -2197,12 +2200,12 @@ MicrosoftRecordLayoutBuilder::getAdjuste
     // Capture required alignment as a side-effect.
     RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
   }
-  // Respect pragma pack.
-  if (!MaxFieldAlignment.isZero())
-    Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
   // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
-  if (!(FD->isBitField() && IsUnion))
+  if (!(FD->isBitField() && IsUnion)) {
     Alignment = std::max(Alignment, Info.Alignment);
+    if (!MaxFieldAlignment.isZero())
+      Alignment = std::min(Alignment, MaxFieldAlignment);
+  }
   return Info;
 }
 

Modified: cfe/trunk/test/Layout/ms-x86-pack-and-align.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Layout/ms-x86-pack-and-align.cpp?rev=199172&r1=199171&r2=199172&view=diff
==============================================================================
--- cfe/trunk/test/Layout/ms-x86-pack-and-align.cpp (original)
+++ cfe/trunk/test/Layout/ms-x86-pack-and-align.cpp Mon Jan 13 18:54:36 2014
@@ -349,6 +349,28 @@ struct JC : JB, JA { };
 // CHECK-X64-NEXT:      | [sizeof=4, align=4
 // CHECK-X64-NEXT:      |  nvsize=4, nvalign=4]
 
+#pragma pack()
+struct KA { char a; };
+#pragma pack(1)
+struct KB : KA { __declspec(align(2)) char a; };
+
+// CHECK: *** Dumping AST Record Layout
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT:    0 | struct KB
+// CHECK-NEXT:    0 |   struct KA (base)
+// CHECK-NEXT:    0 |     char a
+// CHECK-NEXT:    2 |   char a
+// CHECK-NEXT:      | [sizeof=4, align=2
+// CHECK-NEXT:      |  nvsize=3, nvalign=2]
+// CHECK-x64: *** Dumping AST Record Layout
+// CHECK-x64: *** Dumping AST Record Layout
+// CHECK-x64-NEXT:    0 | struct KB
+// CHECK-x64-NEXT:    0 |   struct KA (base)
+// CHECK-x64-NEXT:    0 |     char a
+// CHECK-x64-NEXT:    2 |   char a
+// CHECK-x64-NEXT:      | [sizeof=4, align=2
+// CHECK-x64-NEXT:      |  nvsize=3, nvalign=2]
+
 int a[
 sizeof(X)+
 sizeof(Y)+
@@ -364,4 +386,5 @@ sizeof(YF)+
 sizeof(YF)+
 sizeof(D2)+
 sizeof(JC)+
+sizeof(KB)+
 0];