[lld] 691e3c6 - [lld-macho] Fix `Defined` size increase with `-mms-bitfields` (#107545)

[via llvm-commits]

Author: Daniel Bertalan
Date: 2024-09-06T10:58:19+02:00
New Revision: 691e3c64d08c32955c8f5f740d4ce0db00ee2307

URL: https://github.com/llvm/llvm-project/commit/691e3c64d08c32955c8f5f740d4ce0db00ee2307
DIFF: https://github.com/llvm/llvm-project/commit/691e3c64d08c32955c8f5f740d4ce0db00ee2307.diff

LOG: [lld-macho] Fix `Defined` size increase with `-mms-bitfields` (#107545)

Under the Microsoft ABI, only those bit fields can be merged whose
underlying types have the same size.

d175616 (`[lld-macho][arm64] Enhance safe ICF with thunk-based
deduplication`) added an enum field (`identicalCodeFoldingKind`) next to
booleans in the `Defined` class, which increased the size under the MS
ABI. On MinGW targets, this triggered the `static_assert` which checks
the size of `Defined` (for MSVC targets, the check is disabled due to
another problem). Let's store it as a `uint8_t` to allow merging to take
place.

Fixes #107511

Added: 
    

Modified: 
    lld/MachO/Symbols.h

Removed: 
    


################################################################################
diff  --git a/lld/MachO/Symbols.h b/lld/MachO/Symbols.h
index 70fd195f25c929..beb97b35bf8817 100644
--- a/lld/MachO/Symbols.h
+++ b/lld/MachO/Symbols.h
@@ -14,6 +14,7 @@
 #include "Target.h"
 
 #include "llvm/Object/Archive.h"
+#include "llvm/Support/Compiler.h"
 #include "llvm/Support/MathExtras.h"
 
 namespace lld {
@@ -152,7 +153,8 @@ class Defined : public Symbol {
   // Whether this symbol should appear in the output symbol table.
   bool includeInSymtab : 1;
   // The ICF folding kind of this symbol: None / Body / Thunk.
-  ICFFoldKind identicalCodeFoldingKind : 2;
+  LLVM_PREFERRED_TYPE(ICFFoldKind)
+  uint8_t identicalCodeFoldingKind : 2;
   // Symbols marked referencedDynamically won't be removed from the output's
   // symbol table by tools like strip. In theory, this could be set on arbitrary
   // symbols in input object files. In practice, it's used solely for the