[lld] r266857 - Revert "[ELF] - Avoid using memset for zero-initialization of struct member. NFC."

[Sean Silva via llvm-commits]

Author: silvas
Date: Tue Apr 19 23:26:16 2016
New Revision: 266857

URL: http://llvm.org/viewvc/llvm-project?rev=266857&view=rev
Log:
Revert "[ELF] - Avoid using memset for zero-initialization of struct member. NFC."

This reverts commit r266618. It breaks basically everything.

I think VS2013 doesn't interpret this code in the same way.
The size field (at least) is left uninitialized, causing all sorts of havok
(e.g. creating a 34GB file for a trivial hello world program).

The offending compiler reports itself as follows:

    c:\release-vs2013>cl /?
    Microsoft (R) C/C++ Optimizing Compiler Version 18.00.40629 for x64
    Copyright (C) Microsoft Corporation.  All rights reserved.

Modified:
    lld/trunk/ELF/OutputSections.cpp
    lld/trunk/ELF/OutputSections.h

Modified: lld/trunk/ELF/OutputSections.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.cpp?rev=266857&r1=266856&r2=266857&view=diff
==============================================================================
--- lld/trunk/ELF/OutputSections.cpp (original)
+++ lld/trunk/ELF/OutputSections.cpp Tue Apr 19 23:26:16 2016
@@ -44,6 +44,7 @@ template <class ELFT>
 OutputSectionBase<ELFT>::OutputSectionBase(StringRef Name, uint32_t Type,
                                            uintX_t Flags)
     : Name(Name) {
+  memset(&Header, 0, sizeof(Elf_Shdr));
   Header.sh_type = Type;
   Header.sh_flags = Flags;
 }

Modified: lld/trunk/ELF/OutputSections.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/OutputSections.h?rev=266857&r1=266856&r2=266857&view=diff
==============================================================================
--- lld/trunk/ELF/OutputSections.h (original)
+++ lld/trunk/ELF/OutputSections.h Tue Apr 19 23:26:16 2016
@@ -97,7 +97,7 @@ public:
 
 protected:
   StringRef Name;
-  Elf_Shdr Header = {};
+  Elf_Shdr Header;
 };
 
 template <class ELFT> class GotSection final : public OutputSectionBase<ELFT> {