fix PR6921 a different way. Intead of increasing the
alignment of globals with a specified alignment, we fix
common variables to obey their alignment. Add a comment
explaining why this behavior is important.
llvm-svn: 102365
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 4660e1b..6fc8833 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -228,7 +228,15 @@
const TargetData *TD = TM.getTargetData();
unsigned Size = TD->getTypeAllocSize(GV->getType()->getElementType());
- unsigned AlignLog = TD->getPreferredAlignmentLog(GV);
+
+ // If the alignment is specified, we *must* obey it. Overaligning a global
+ // with a specified alignment is a prompt way to break globals emitted to
+ // sections and expected to be contiguous (e.g. ObjC metadata).
+ unsigned AlignLog;
+ if (unsigned GVAlign = GV->getAlignment())
+ AlignLog = Log2_32(GVAlign);
+ else
+ AlignLog = TD->getPreferredAlignmentLog(GV);
// Handle common and BSS local symbols (.lcomm).
if (GVKind.isCommon() || GVKind.isBSSLocal()) {