21. 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'.

21.1 Controlling the Compilation Driver, `gcc'		Controlling how the driver runs the compilation passes.
21.2 Run-time Target Specification		Defining `-m' options like `-m68000' and `-m68020'.
21.3 Defining data structures for per-function information.
21.4 Storage Layout		Defining sizes and alignments of data.
21.5 Layout of Source Language Data Types		Defining sizes and properties of basic user data types.
21.6 Register Usage		Naming and describing the hardware registers.
21.7 Register Classes		Defining the classes of hardware registers.
21.8 Stack Layout and Calling Conventions		Defining which way the stack grows and by how much.
21.9 Implementing the Varargs Macros		Defining the varargs macros.
21.10 Trampolines for Nested Functions		Code set up at run time to enter a nested function.
21.11 Implicit Calls to Library Routines		Controlling how library routines are implicitly called.
21.12 Addressing Modes		Defining addressing modes valid for memory operands.
21.13 Condition Code Status		Defining how insns update the condition code.
21.14 Describing Relative Costs of Operations		Defining relative costs of different operations.
21.15 Dividing the Output into Sections (Texts, Data, ...)		Dividing storage into text, data, and other sections.
21.16 Position Independent Code		Macros for position independent code.
21.17 Defining the Output Assembler Language		Defining how to write insns and pseudo-ops to output.
21.18 Controlling Debugging Information Format		Defining the format of debugging output.
21.19 Cross Compilation and Floating Point		Handling floating point for cross-compilers.
21.20 Mode Switching Instructions		Insertion of mode-switching instructions.
21.21 Miscellaneous Parameters		Everything else.