Clang-3.8在從全局變量編譯來自llvm字節碼的目標文件時對`main'的未定義引用

Question

我試圖通過C++ API在llvm中實現嵌套函數。在我執行語義檢查後（爲了確保要編譯的程序具有正確的嵌套引用等），我在llvm的同一個作用域中定義了所有函數，並將所有變量設置爲全局變量。我期待這個工作，但我發現有很大的問題，而自己從.o文件將得到一個可執行文件，命令：

"llvm-as-3.8 output.ll| llc-3.8 -filetype=obj | clang-3.8 ../library/library.a -v -o out" 

通過使用任一llvm::GlobalValue::WeakAnyLinkage或llvm::GlobalValue::ExternalLinkage聯動全局變量我得到：

/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 0 has invalid symbol index 11

/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 1 has invalid symbol index 12

/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 8 has invalid symbol index 12

...

/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_line): relocation 0 has invalid symbol index 2

/usr/bin/../lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o: In function `_start':

(.text+0x20): undefined reference to `main'

這似乎已經與主要的定義，誰在我的紅外代碼的定義來做爲代表：

; Function Attrs: nounwind uwtable define void @main() #0 {

問題是，當我沒有使用全局變量時，同樣的命令沒有任何問題，當然，在子函數中使用變量的情況下，這是我嘗試將alloca更改爲全局的原因。

幫助找到解決此問題的方法。 在此先感謝。 注1：我用LLVM-3.8

UPDATE： 當我從鐺命令的結果是刪除-v：

refined_output.o: In function bsort': refined_output.ll:(.text+0x4): undefined reference to x' refined_output.ll:(.text+0xa): undefined reference to n' refined_output.ll:(.text+0x10): undefined reference to changed' refined_output.ll:(.text+0x22): undefined reference to i' refined_output.ll:(.text+0x2c): undefined reference to changed' refined_output.ll:(.text+0x42): undefined reference to i' refined_output.ll:(.text+0x48): undefined reference to n' refined_output.ll:(.text+0x50): undefined reference to i' refined_output.ll:(.text+0x59): undefined reference to x' refined_output.ll:(.text+0x60): undefined reference to i' refined_output.ll:(.text+0x75): undefined reference to x' refined_output.ll:(.text+0x7c): undefined reference to i' refined_output.ll:(.text+0x95): undefined reference to changed' refined_output.ll:(.text+0xa3): undefined reference to changed' refined_output.o: In function swap': refined_output.ll:(.text+0xc3): undefined reference to x.1' refined_output.ll:(.text+0xca): undefined reference to y' refined_output.ll:(.text+0xd1): undefined reference to x.1' refined_output.ll:(.text+0xd9): undefined reference to t' refined_output.ll:(.text+0xe0): undefined reference to x.1' refined_output.ll:(.text+0xe7): undefined reference to y' refined_output.ll:(.text+0xf2): undefined reference to y' refined_output.ll:(.text+0xf8): undefined reference to t' refined_output.o: In function main': refined_output.ll:(.text+0x102): undefined reference to i.4' refined_output.ll:(.text+0x10c): undefined reference to seed' refined_output.ll:(.text+0x123): undefined reference to x.2' refined_output.ll:(.text+0x12a): undefined reference to i.4' refined_output.ll:(.text+0x130): undefined reference to seed' refined_output.ll:(.text+0x15d): undefined reference to seed' refined_output.ll:(.text+0x166): undefined reference to i.4' refined_output.ll:(.text+0x16c): undefined reference to i.4' refined_output.ll:(.text+0x177): undefined reference to x.2' refined_output.ll:(.text+0x18d): undefined reference to x.2' refined_output.ll:(.text+0x19e): undefined reference to x.2' refined_output.o: In function printArray': refined_output.ll:(.text+0x1c4): undefined reference to msg' refined_output.ll:(.text+0x1cb): undefined reference to x.2' refined_output.ll:(.text+0x1d1): undefined reference to n.3' refined_output.ll:(.text+0x1d8): undefined reference to msg' refined_output.ll:(.text+0x1e3): undefined reference to i.4' refined_output.ll:(.text+0x1f3): undefined reference to x.2' refined_output.ll:(.text+0x1fa): undefined reference to i.4' refined_output.ll:(.text+0x208): undefined reference to i.4' refined_output.ll:(.text+0x20e): undefined reference to i.4' refined_output.ll:(.text+0x214): undefined reference to n.3' refined_output.ll:(.text+0x21c): undefined reference to i.4'

clang: error: linker command failed with exit code 1 (use -v to see invocation)

，所有這個變量在我的計劃中LLVM IR開始定義作爲：

@x = external global i32* 
@n = external global i32 
@i = external global i32 
@changed = external global i1 
@x.1 = external global i32* 
@y = external global i32* 
@t = external global i32 
@msg = external global i8* 
@x.2 = external global i32* 
@n.3 = external global i32 
@i.4 = external global i32 
@const_string_temp = private constant [3 x i8] c", \00", align 1 
@const_string_temp.5 = private constant [2 x i8] c"\0A\00", align 1 
@i.6 = external global i32 
@x.7 = external global i32 
@seed = external global i32 
@const_string_temp.8 = private constant [16 x i8] c"Initial array: \00", align 1 
@const_string_temp.9 = private constant [15 x i8] c"Sorted array: \00", align 1 

我希望這可以幫助你，幫助我---或者在我的紅外代碼生成中發現問題。

我期待着它..

Answer 1

@x = external global i32* 

等都是全局變量聲明，而不是定義。因此，「未定義參考」錯誤是有效的，您確實需要定義它們。

有關更多信息，請參見http://llvm.org/docs/LangRef.html#global-variables

還要注意，LLVM-AS/LLC一部分是多餘的 - 鐺可以編譯.ll/.BC文件就好了。