无法使用MS Linker链接LLVM编译器生成的obj文件 [英] Failed to link obj files generated by LLVM compiler using MS Linker

问题描述

我使用llvm在线编译器来编译示例C代码，

I used llvm online compiler to compile my sample C code,

int main() { return 0; }

生成的LLVM程序集

 ; ModuleID = '/tmp/webcompile/_31588_0.bc'
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

define i32 @main() nounwind uwtable {
  %1 = alloca i32, align 4
  store i32 0, i32* %1
  ret i32 0
}

然后我将LLVM程序集编译为obj文件

then I compiled LLVM assembly to obj file,

llc -filetype=obj a.ll

当我尝试使用link.exe a.o链接obj文件时，出现错误

when I tried to link the obj file using link.exe a.o I got the error

 fatal error LNK1107: invalid or corrupt file: cannot read at 0x438

如何生成正确的obj文件以馈入link.exe?

How can I generate the right obj file to feed into link.exe?

更多信息

• 我使用Visual Studio 11构建了LLVM.我没有安装cygwin.
• link.exe也来自Visual Studio 11
• LLVM是从最新的源代码构建的.

如果我使用VC ++编译器将相同的代码编译为汇编，则看起来像这样，

If I compile the same code using VC++ compiler into assembly, it looks like this,

; Listing generated by Microsoft (R) Optimizing Compiler Version 17.00.50402.0 

include listing.inc

INCLUDELIB LIBCMT
INCLUDELIB OLDNAMES

PUBLIC  main
; Function compile flags: /Odtp
_TEXT   SEGMENT
main    PROC
; File c:\tmp\u.c
; Line 1
    xor eax, eax
    ret 0
main    ENDP
_TEXT   ENDS
END

llc -filetype=asm j.ll生成以下代码.使用ml.exe也会失败.

llc -filetype=asm j.ll generates the following code. It fails with ml.exe either.

    .def     _main;
    .scl    2;
    .type   32;
    .endef
    .text
    .globl  _main
    .align  16, 0x90
_main:                                  # @main
# BB#0:
    pushl   %eax
    movl    $0, (%esp)
    xorl    %eax, %eax
    popl    %edx
    ret

推荐答案

您的IR用于x86-64/linux，如目标三元组中所述.因此，llc将为您生成(默认情况下)ELF对象文件，而不是COFF.肯定link.exe将不会接受它.

You IR is for x86-64/linux as stated in target triplet. So, llc will generate (by default) ELF object file for you, not COFF. Surely link.exe will not accept it.

请注意，您不能仅将目标三元组更改为某些窗口并假定一切正常:

Note that you cannot just change the target triple to some windows and assume everything will work:

1. 发射COFF目标代码是WIP
2. C/C ++不是目标无关的语言，因此，您不能在此处获取目标无关的IR: http://llvm.org/docs/FAQ.html#platformindependent

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