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I have a very very simple C++ file as follows that I'm compiling on Solaris 5-10 with the CC compiler. Here is the source code in my file myTest.C:

#include <map>
std::map<int, bool> myVar2;

I would like to first run the CC pre-processor on this file, examine the pre-processed file, and then compile that pre-processed file into an object file. I call this "indirect-compiling". To do this, I do the following:

% CC -P -o myFile_indirect.i myFile.C
% CC -c -o myFile_indirect.o myFile_indirect.i

I would also like to compile this file without a separate pre-processing step as is normally done. I call this "direct-compiling". To do this, I do the following:

% CC -c -o myFile_direct.o myFile.C

In theory, myFile_direct.o and myFile_indirect.o should be functionally equivalent. They should certainly contain the same number of symbols in their respective symbol tables right? So let's examine their symbols:

% gnm myFile_direct.o | c++filt > direct_symbols.txt
% gnm myFile_indirect.o | c++filt > indirect_symbols.txt
% wc -l *direct_symbols.txt
55 direct_symbols.txt
43 indirect_symbols.txt

Shockingly, the directly-compiled object file contains 12 symbols that are absent from the indirectly compiled file. Why? This seems like a serious bug to me. Why are these symbols absent from the indirectly compiled file? If they are unnecessary, why are they included in the directly compiled file? Isn't direct-compilation supposed to do the same pre-processing first and just hide it from the user? What is going on here?

PS. I don't recognize the twelve extra symbols nor do I understand what their purpose is:

00000010 T __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__nil()
00000010 T __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::iterator __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::erase(__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::iterator)
00000010 T void __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__erase(__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*)
00000010 T __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*&__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__right(__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*)
00000010 T __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::iterator&__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::iterator::operator++()
00000010 T __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__maximum(__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*)
00000010 T __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__minimum(__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*)
00000010 T __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*&__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__leftmost()
00000010 T __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*&__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rightmost()
00000010 T void __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__erase_leaf(__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*)
00000010 T void __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rotate_left(__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*)
00000010 T void __rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rotate_right(__rwstd::__rb_tree<int,std::pair<const int,bool>,__rwstd::__select1st<std::pair<const int,bool>,int>,std::less<int>,std::allocator<std::pair<const int,bool> > >::__rb_tree_node*)
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1 回答 1

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尝试使用CC -E代替CC -P. 当我这样做时，nm(1)列表是相同的，并且目标文件仅相差几个字节（鉴于我可以在这种差异中看到文件*.c的名称并不奇怪）。*.i*.o

手册页并没有真正解释这两个标志之间的区别，但确实强调了 C++，-E所以我想知道是否-P只打算成为 C。

如果您想弄清楚直接方法的真正含义，那么这可能会很有启发性：

truss -f -a -texec CC myFile.C

直接编译方法不调用CC -P，CC -E而是调用ccfe 一大堆标志（fbe然后ld......）。

于 2012-10-15T23:03:19.243 回答