The assembler output
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The assembler output
(last updated for fpc version 1.0.x)
All code is generated via special linked lists of instructions. The base of this is a special object, an abstract assembler which implements all directives which are usually implemented in the different assemblers available on the market. When the code generator and parser generates the final output, it is generated as a linked list for each of the sections available for the output assembler. Each entry in the linked list is either an instruction, or one of the abstract directives for the assembler.
http://www.pjh2.de/fpc/CompilerInternalsFigure11.png
Assembler generation organisation
The different possible sections which are output are as follows:
| Internal section name | Description |
|---|---|
| ExparAsmList | temporary list |
| DataSegment | initialized variables |
| CodeSegment | instructions and general code directives |
| DebugList | debugging information |
| WithDebugList | ??????????????? |
| Consts read | only constants |
| ImportSection | imported symbols |
| ExportSection | exported symbols |
| ResourceSection | Resource data |
| RttiList | runtime type information data |
| ResourceStringList | resource string data |
The following directives for the abstract assembler currently exist:
Abstract assembler node types:
| Node entry Type | Description |
|---|---|
| Ait_None | This entry in the linked list is invalid (this should normally never occur) |
| Ait_Direct | Direct output to the resulting assembler file (as string) |
| Ait_String | Shortstring with a predefined length |
| Ait_Label | Numbered assembler label used for jumps |
| Ait_Comment | Assembler output comment |
| Ait_Instruction | Processor specific instruction |
| Ait_DataBlock | Unitialized data block (BSS) |
| Ait_Symbol | Entry represents a symbol (exported, imported, or other public symbol type)
Possible symbol types : NONE, EXTERNAL, LOCAL and GLOBAL eg : A symbol followed by an Ait_const_32bit |
| Ait_Symbol_End | Symbol end (for example the end of a routine) |
| Ait_Const_32bit | Initialized 32-bit constant (without a symbol) |
| Ait_Const_16bit | Initialized 16-bit constant (without a symbol) |
| Ait_Const_8bit | Initialized 8-bit constant (without a symbol) |
| Ait_Const_symbol | ???????????? |
| Ait_Real_80bit | (x86) Initialized 80-bit floating point constant (without symbol) |
| Ait_Real_64bit | Initialized Double IEEE floating point constant (without symbol) |
| Ait_Real_32bit | Initialized Single IEEE floating point constant (without symbol) |
| Ait_Comp_64bit | (x86) Initialized 64-bit floating point integer (without symbol) |
| Ait_Align Alignment | directive |
| Ait_Section Section | directive |
| Ait_const_rva | (Win32) |
| Ait_Stabn | stabs debugging information (numerical value) |
| Ait_Stabs | stabs debugging information (string) |
| Ait_Force_Line stabs | debugging line information |
| Ait_Stab_Function_Name | stabs debug information routine name |
| Ait_Cut | Cut in the assembler files (used for smartlinking) |
| Ait_RegAlloc | Debugging information for the register allocator |
| Ait_Marker | ???????????? |
| Ait_Frame | (Alpha) |
| Ait_Ent | (Alpha) |
| Ait_Labeled_Instruction | (m68k) |
| Ait_Dummy | Unused - should never appear |
