Target Description Macros

In addition to the file `machine.md', a machine description includes a C header file conventionally given the name `machine.h'. This header file defines numerous macros that convey the information about the target machine that does not fit into the scheme of the `.md' file. The file `tm.h' should be a link to `machine.h'. The header file `config.h' includes `tm.h' and most compiler source files include `config.h'.

• Driver: Controlling how the driver runs the compilation passes.
• Run-time Target: Defining `-m' options like `-m68000' and `-m68020'.
• Storage Layout: Defining sizes and alignments of data.
• Type Layout: Defining sizes and properties of basic user data types.
• Registers: Naming and describing the hardware registers.
• Register Classes: Defining the classes of hardware registers.
• Stack and Calling: Defining which way the stack grows and by how much.
• Varargs: Defining the varargs macros.
• Trampolines: Code set up at run time to enter a nested function.
• Library Calls: Controlling how library routines are implicitly called.
• Addressing Modes: Defining addressing modes valid for memory operands.
• Condition Code: Defining how insns update the condition code.
• Costs: Defining relative costs of different operations.
• Sections: Dividing storage into text, data, and other sections.
• PIC: Macros for position independent code.
• Assembler Format: Defining how to write insns and pseudo-ops to output.
• Debugging Info: Defining the format of debugging output.
• Cross-compilation: Handling floating point for cross-compilers.
• Misc: Everything else.