[llvm-dev] objc object file generated for gnustep runtime for ELF target is too big
Perevalov Alexey via llvm-dev
llvm-dev at lists.llvm.org
Tue Sep 27 00:06:51 PDT 2016
От: mehdi.amini at apple.com <mehdi.amini at apple.com> от имени Mehdi Amini <mehdi.amini at apple.com>
Отправлено: 27 сентября 2016 г. 8:46
Кому: Perevalov Alexey
Копия: cfe-users at lists.llvm.org; llvm-dev at lists.llvm.org
Тема: Re: [llvm-dev] objc object file generated for gnustep runtime for ELF target is too big
> On Sep 26, 2016, at 6:33 AM, Perevalov Alexey via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> Dear community,
> I'm using gnustep runtime -fobjc-runtime=gnustep with gnustep-libobjc2 (https://github.com/gnustep/libobjc2) and
> For following source file
> #import <Foundation/Foundation.h>
> #import <UIKit/UIKit.h>
> int main(void)
> NSString *str = [NSString stringWithCString:"TEST"];
> NSLog(@"test object %@", str);
> return 0;
> Compilation in xcode's clang
I think, it doesn't matter, due to with xcode's clang all fine
but if you intersting,
xcrun -sdk iphoneos clang --version
Apple LLVM version 7.0.0 (clang-700.1.76)
Thread model: posix
also all fine with open source llvm clang if I choose ios as -fobjc-runtime, I got troubles only with gnustep runtime in clang+llvm-3.8.0 and 3.9.x.
> xcrun -sdk iphoneos clang -arch armv7s -mios-version-min=6.1 -c test_foundation.m -o test_foundation_apple.o
> gives following result:
> 1. object file has only 3156 bytes size
> 2. and in disassembler only main function
> 3. the final executable will be 49992 bytes size in this case
> But compilation in llvm's clang downloaded from http://llvm.org/releases/3.8.0/clang+llvm-3.8.0-x86_64-apple-darwin.tar.xz
> clang version 3.8.0 (tags/RELEASE_380/final)
> Target: x86_64-apple-darwin15.0.0
> Thread model: posix
> gives another results:
> 1. object file has 159044 bytes size
> 2. in disassembler a lot of unnecessary .objc_property_list, .objc_method_list, .objc_protocol_list and .objc_protocol in .bss and .data section
> 3. the final binary size is 101837 bytes size
> If comment in above sample #import <UIKit/UIKit.h, the size of object file and binary file in xcode compilation will be the same,
> but size binary and object file in case of clang+llvm-3.8.0-x86_64-apple-darwin compilation will be reduced sufficiently:
> binary 28569 and object 36952 accordingly.
> Looks like all protocols from UIKit.h is placed into binary/object even it's not used there.
> I got 3.9.0 from public git (branch release_39 of clang git repository) and found that all protocols interpret as definition (isThisDeclarationADefinition),
> and in CGObjCGNU.cpp it's placed into object file whenever it's used or not. With the same open source compiler and -fobjc-runtime=ios protocols are not putting into
> object file even in compilation for ELF (I used -target arm-linux-gnueabi).
> I used default binutil linker, not llvm's ld.ldd, due to I have problem with relocation on ARM.
> I didn't use LTO, due to my linker doesn't have plugin support (I didnt' yet recompile it).
> Could somebody point me where to solve that problem, is it AST generation stage, or linkage stage or maybe it's not a problem and just LTO could be solution here?
> p.s. It's not only one issue found by me in gnustep runtime generation, and I'll report these issues in next emails.
> Best regards,
> Alexey Perevalov
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
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