[PATCH] D14980: PR18513: make gcc compatible layout for bit-fields with explicit aligned attribute

[Richard Smith via cfe-commits]

rsmith added a subscriber: rsmith.
rsmith added a comment.

GCC's behavior (`aligned` on a field specifies the alignment of the start of that field) makes a little more sense to me than Clang's behavior (the type and alignment of a field specify a flavour of storage unit, and the field goes in the next such storage unit that it fits into), but both seem defensible.

John, are we intentionally deviating from GCC's behaviour here?


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Comment at: lib/AST/RecordLayoutBuilder.cpp:1606
@@ -1605,1 +1605,3 @@
+    } else if (ExplicitFieldAlign)
+      FieldOffset = llvm::RoundUpToAlignment(FieldOffset, ExplicitFieldAlign);
 
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You should round up to `FieldAlign` here.


http://reviews.llvm.org/D14980