Hojun-Cho
1b0955c97b
First step toward top-level mutable `let`. Adds a sibling directive to DATA whose bytes land in a separate writable .data PROGBITS section (SHF_ALLOC|SHF_WRITE, STT_OBJECT) instead of .text. The section is emitted only when DATAW was used, so inputs without it produce a byte-identical .o — tests 991 (selfhost .o diff) and 995 (self-rebuild) keep passing unchanged. w6l still treats data-resident syms as undefined; that's the next step.
116 lines
2.5 KiB
C
116 lines
2.5 KiB
C
/*
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* a.h — w6a-private header. Modelled on Plan 9 cmd/6a/a.h, trimmed
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* to the instruction subset that w6c emits.
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*
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* w6a is line-oriented and has no preprocessor: each non-blank, non-
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* label line is one instruction. We read the whole file into a list
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* of `Aprog`s, then encode and emit ELF64.
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*/
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#ifndef SIX_A_H
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#define SIX_A_H
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#include "6.out.h"
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#include <stddef.h>
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#include <stdint.h>
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#include <stdio.h>
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typedef int8_t i8;
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typedef int16_t i16;
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typedef int32_t i32;
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typedef int64_t i64;
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typedef uint8_t u8;
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typedef uint16_t u16;
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typedef uint32_t u32;
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typedef uint64_t u64;
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typedef struct Aoperand Aoperand;
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typedef struct Aprog Aprog;
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typedef struct Asym Asym;
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typedef struct Areloc Areloc;
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typedef struct Asm Asm;
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struct Aoperand {
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int type; /* D_NONE, D_AX..D_R15, D_CONST, D_INDIR, D_EXTERN, D_BRANCH */
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int reg; /* base register for D_INDIR */
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i64 offset; /* immediate or displacement */
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const char *sym;
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};
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struct Aprog {
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int as; /* opcode (A_*) */
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Aoperand from;
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Aoperand to;
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int line;
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const char *label; /* label preceding this prog, if any */
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Aprog *link;
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/* for A_DATA: raw payload bytes interned by the parser */
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u8 *bytes;
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u64 nbytes;
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};
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struct Asym {
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const char *name;
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int defined; /* 1 if we own its address */
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int is_text; /* if 1, address is in .text */
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int is_data; /* if 1, address is in .data (mutually exclusive with is_text) */
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int is_global; /* exported (TEXT) */
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u64 addr; /* offset within section if defined */
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int idx; /* ELF symtab index, filled at emit time */
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Asym *next;
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};
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struct Areloc {
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u64 off; /* offset within .text where relocation lands */
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int kind; /* R_X86_64_PLT32 (4), R_X86_64_PC32 (2) */
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Asym *sym;
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i64 addend;
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Areloc *next;
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};
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struct Asm {
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/* parser state */
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const char *file;
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const char *src;
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u64 srclen;
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u64 pos;
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int line;
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/* program list */
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Aprog *head, *tail;
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/* output text section */
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u8 *text;
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u64 textcap, textlen;
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/* output data section (writable). Empty unless any DATAW directive
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* was seen; in that case obj.c emits an extra .data PROGBITS
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* section with SHF_WRITE. */
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u8 *data;
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u64 datacap, datalen;
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/* symbols */
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Asym *syms;
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Areloc *relocs;
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int errs;
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};
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/* lex.c / parse.c */
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void a_init(Asm*, const char *file, const char *src, u64 len);
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int a_parse(Asm*);
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/* asm.c */
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int a_encode(Asm*);
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/* obj.c */
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int a_emit_elf(Asm*, FILE *out);
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/* helpers */
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Asym *a_intern(Asm*, const char *name);
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void a_emit_byte(Asm*, u8);
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void a_emit_u32(Asm*, u32);
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void a_emit_data_byte(Asm*, u8);
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void a_addreloc(Asm*, u64 off, int kind, Asym *s, i64 add);
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#endif
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