What Happens After The Compiler in C++ (How Linking Works)
summary
Walks through real object files and executables produced by Compiler Explorer and inspects them with objdump and readelf, showing raw bytes, relocations (e.g. call E8 with a zero operand patched to -0x21), how the linker lays out .text/.data/.bss/.rodata, why -fPIC changes code shape, how writable globals use a per-process global offset table (GOT) and lazy function resolution uses the procedure linkage table (PLT) with the loader fixing addresses at runtime.
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chapters (21)
- 0:00Linking in C++
- 1:25Simple C++ program example
- 3:10Refactoring and compiler output
- 5:37Inspecting object files
- 9:49Linker resolves addresses
- 11:34Understanding relocations
- 17:01Relocations for function calls
- 19:27Linking object files
- 22:57Data access in compiled code
- 27:31Global variables and static storage
- 31:41Static globals need relocations
- 33:10ELF global data sections
- 39:58Static vs dynamic linking
- 41:03Dynamic linking and relocations
- 42:29Shared libraries at load time
- 44:33Global Offset Table (GOT)
- 47:24Role of -fPIC
- 50:15Populating GOT at startup
- 52:21Function calls in shared libraries
- 53:46Lazy loading with PLT/GOT
- 57:37Summary of linking
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