Implement #pragma pack use in structure packing. The general approach
is to encode the state of the #pragma pack stack as an attribute when
the structure is declared.
- Extend PackedAttr to take an alignment (in bits), and reuse for
both __attribute__((packed)) (which takes no argument, instead
packing tightly (to "minimize the memory required") and for #pragma
pack (which allows specification of the maximum alignment in
bytes). __attribute__((packed)) is just encoded as Alignment=1.
This conflates two related but different mechanisms, but it didn't
seem worth another attribute.
- I have attempted to follow the MSVC semantics as opposed to the gcc
ones, since if I understand correctly #pragma pack originated with
MSVC. The semantics are generally equivalent except when the stack
is altered during the definition of a structure; its not clear if
anyone does this in practice. See testcase if curious.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@57623 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index 3ab0c91..5c04bf0 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -256,7 +256,7 @@
}
if (TagDecl *TD = dyn_cast<TagDecl>(d))
- TD->addAttr(new PackedAttr());
+ TD->addAttr(new PackedAttr(1));
else if (FieldDecl *FD = dyn_cast<FieldDecl>(d)) {
// If the alignment is less than or equal to 8 bits, the packed attribute
// has no effect.
@@ -266,7 +266,7 @@
diag::warn_attribute_ignored_for_field_of_type,
Attr.getName()->getName(), FD->getType().getAsString());
else
- FD->addAttr(new PackedAttr());
+ FD->addAttr(new PackedAttr(1));
} else
S.Diag(Attr.getLoc(), diag::warn_attribute_ignored,
Attr.getName()->getName());