How Can I Access the Assembly Code Generated from C/C Source Using GCC?

Accessing Assembler Output from C/C Source in GCC

To analyze the compilation process, it is often useful to extract the emitted assembly code. This can be achieved in two ways using GCC:

Using the -S Option:

By adding the -S option to the gcc command, the preprocessor will be invoked, and the initial compilation will occur. However, the process will halt before the assembly stage. This partial compilation output, typically named file_name.s, contains the assembly code that corresponds to the original C/C source.

Using objdump:

If only the object file is available, the objdump utility can be used to extract assembly code. By adding the --disassemble (-d) option, objdump will generate a disassembly of the object file. If the compilation was performed with debug information (using -g), the source lines will be interleaved with the disassembly for better readability.

Example:

gcc -S source_file.c
objdump -S --disassemble object_file.o > assembly_output.txt

The -S option with gcc will generate an assembly file named source_file.s. The objdump command will create a text file named assembly_output.txt containing the disassembly of the object file, with source lines included if available.

Additional objdump options for customizing the output include:

• -rwC: Show symbol relocations, disable line-wrapping, and demangle C names.
• -Mintel: Use Intel syntax for x86 assembly instead of AT&T.

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