From 50e7f45b280f1e7922a6525ace10a6bd33f70fa7 Mon Sep 17 00:00:00 2001
From: Fangrui Song <maskray@google.com>
Date: Tue, 9 Jul 2019 07:12:58 +0000
Subject: [PATCH] [ELF] Assert sizeof(SymbolUnion) <= 80

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D64077

llvm-svn: 365443
---
 lld/ELF/Symbols.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lld/ELF/Symbols.h b/lld/ELF/Symbols.h
index 6ca24d4413af..f9b1fc6c4dcf 100644
--- a/lld/ELF/Symbols.h
+++ b/lld/ELF/Symbols.h
@@ -460,6 +460,11 @@ union SymbolUnion {
   alignas(LazyObject) char F[sizeof(LazyObject)];
 };
 
+// It is important to keep the size of SymbolUnion small for performance and
+// memory usage reasons. 80 bytes is a soft limit based on the size of Defined
+// on a 64-bit system.
+static_assert(sizeof(SymbolUnion) <= 80, "SymbolUnion too large");
+
 template <typename T> struct AssertSymbol {
   static_assert(std::is_trivially_destructible<T>(),
                 "Symbol types must be trivially destructible");