java - Decompile C code with debug info? -


java , python byte code relatively easy decompile compiled machine code generated c/c++ compiler.

i unable find convincing answer why information -g option insufficient de-compilation, sufficient debugging? stuff contained in python/java byte code, makes decompilation easy?

i unable find convincing answer why information -g option insufficient de-compilation, sufficient debugging?

the debugging information contains mapping between addresses in generated code , source files line numbers. debugger not need decompile code - shows original sources. if source files missing, debugger won't magically show them.

that said, presence of debugging info make decompilation easier. if debug info includes layout of used types , function prototypes, decompiler can use , provide more precise decompilation. in many cases, however, still different original source.

for example, here's function decompiled hex-rays decompiler without using debug info:

int __stdcall sub_4050a0(int a1) {   int result; // eax@1    result = a1;   if ( *(_byte *)(a1 + 12) )   {     result = sub_404600(*(_dword *)a1);     *(_byte *)(a1 + 12) = 0;   }   return result; }

since not know type of a1, accesses fields represented additions , casts.

and here's same function after symbol file has been loaded:

void __thiscall mytree::write_page(mytree *this, page *src) {   if ( src->ischanged )   {     cache::set_changed(this->cache, src->baseaddr);     src->ischanged = 0;   } }

you can see it's been improved quite lot.

as why decompiling bytecode easier, in addition npe's answer check this.


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