ncc: describe what each file does in its header
[neatcc/cc.git] / gen.h
blob9ae99bcc71cb09ea658416c722c364f1e690a0f6
1 /* neatcc code generation interface */
2 /* basic types */
3 #define BT_SZMASK 0x00ff
4 #define BT_SIGNED 0x0100
5 #define BT_SZ(bt) ((bt) & BT_SZMASK)
7 #define O_SIGNED 0x100
8 /* binary instructions for o_bop() */
9 #define O_ADD 0x00
10 #define O_SUB 0x01
11 #define O_AND 0x02
12 #define O_OR 0x03
13 #define O_XOR 0x04
14 #define O_SHL 0x10
15 #define O_SHR 0x11
16 #define O_MUL 0x20
17 #define O_DIV 0x21
18 #define O_MOD 0x22
19 #define O_LT 0x30
20 #define O_GT 0x31
21 #define O_LE 0x32
22 #define O_GE 0x33
23 #define O_EQ 0x34
24 #define O_NEQ 0x35
25 /* unary instructions for o_uop() */
26 #define O_NEG 0x40
27 #define O_NOT 0x41
28 #define O_LNOT 0x42
30 /* operations on the stack */
31 void o_bop(int op); /* binary operation */
32 void o_uop(int op); /* unary operation */
33 void o_cast(unsigned bt);
34 void o_memcpy(void);
35 void o_memset(void);
36 void o_call(int argc, int ret);
37 void o_ret(int ret);
38 void o_assign(unsigned bt);
39 void o_deref(unsigned bt);
40 void o_load(void);
41 int o_popnum(long *c);
42 /* pushing values to the stack */
43 void o_num(long n);
44 void o_local(long addr);
45 void o_sym(char *sym);
46 void o_tmpdrop(int n);
47 void o_tmpswap(void);
48 void o_tmpcopy(void);
49 /* handling locals */
50 long o_mklocal(int size);
51 void o_rmlocal(long addr, int sz);
52 long o_arg2loc(int i);
53 /* branches */
54 void o_label(int id);
55 void o_jmp(int id);
56 void o_jz(int id);
57 void o_jnz(int id);
58 /* conditional instructions */
59 void o_fork(void);
60 void o_forkpush(void);
61 void o_forkjoin(void);
62 /* data/bss sections */
63 long o_dsnew(char *name, int size, int global);
64 void o_dscpy(long addr, void *buf, int len);
65 void o_dsset(char *name, int off, unsigned bt);
66 void o_bsnew(char *name, int size, int global);
67 /* functions */
68 void o_func_beg(char *name, int argc, int global, int vararg);
69 void o_func_end(void);
70 /* output */
71 void o_write(int fd);
72 /* passes */
73 void o_pass1(void);
74 void o_pass2(void);
77 * neatcc architecture-dependent code-generation interface
79 * To make maintaining three different architectures easier and unifying the
80 * optimization patch, I've extracted gen.c from x86.c and arm.c. The i_*()
81 * functions are now the low level architecture-specific code generation
82 * entry points. The differences between RISC and CISC architectures,
83 * actually the annoying asymmetry in CISC architecture, made this interface
84 * a bit more complex than it could have ideally been. Nevertheless, the
85 * benefits of extracting gen.c and the cleaner design, especially with the
86 * presence of the optimization patch, is worth the added complexity.
88 * I tried to make the interface as small as possible. I'll describe the
89 * key functions and macros here. Overall, there were many challenges for
90 * extracting gen.c including:
91 * + Different register sets; caller/callee saved and argument registers
92 * + CISC-style instructions that work on limited registers and parameters
93 * + Different instruction formats and immediate value limitations
94 * + Producing epilog, prolog, and local variable addresses when optimizing
96 * Instructions:
97 * + i_reg(): The mask of allowed registers for each operand of an instruction.
98 * If md is zero, we assume the destination register should be equal to the
99 * first register, as in CISC architectures. m2 can be zero which means
100 * the instruction doesn't have three operands. mt denotes the mask of
101 * registers that may lose their contents after the instruction.
102 * + i_load(), i_save(), i_mov(), i_num(), i_sym(): The name is clear.
103 * + i_imm(): Specifies if the given immediate can be encoded for the given
104 * instruction.
105 * + i_jmp(), i_fill(): Branching instructions. If rn >= 0, the branch is
106 * a conditional branch: jump only the register rn is zero (or nonzero if
107 * jc is nonzero). nbytes specifies the number of bytes necessary for
108 * holding the jump distance; useful if the architecture supports short
109 * branching instructions. i_fill() actually fills the jump at src in
110 * code segment. It returns the amount of bytes jumped.
111 * + i_args(): The offset of the first argument from the frame pointer.
112 * It is probably positive.
113 * + i_args(): The offset of the first local from the frame pointer.
114 * It is probably negative
115 * + tmpregs: Register that can be used for holding temporaries.
116 * + argregs: Register for holding the first N_ARGS arguments.
118 * There are a few other macros defined in arch headers. See x64.h as
119 * an example.
122 #ifdef NEATCC_ARM
123 #include "arm.h"
124 #endif
125 #ifdef NEATCC_X64
126 #include "x64.h"
127 #endif
128 #ifdef NEATCC_X86
129 #include "x86.h"
130 #endif
132 /* intermediate instructions */
133 #define O_IMM 0x200 /* mask for immediate instructions */
134 #define O_MSET 0x51 /* memset() */
135 #define O_MCPY 0x52 /* memcpy() */
136 #define O_MOV 0x53 /* mov */
137 #define O_SX 0x54 /* sign extend */
138 #define O_ZX 0x55 /* zero extend */
140 void i_load(int rd, int rn, int off, int bt);
141 void i_save(int rd, int rn, int off, int bt);
142 void i_mov(int rd, int rn);
143 void i_reg(int op, int *md, int *m1, int *m2, int *mt);
144 void i_op(int op, int rd, int r1, int r2);
145 int i_imm(int op, long imm);
146 void i_op_imm(int op, int rd, int r1, long n);
148 void i_num(int rd, long n);
149 void i_sym(int rd, char *sym, int off);
151 void i_jmp(int rn, int jc, int nbytes);
152 long i_fill(long src, long dst, int nbytes);
154 void i_call(char *sym, int off);
155 void i_call_reg(int rd);
156 void i_memset(int r0, int r1, int r2);
157 void i_memcpy(int r0, int r1, int r2);
159 int i_args(void); /* the address of the first arg relative to fp */
160 int i_sp(void); /* the address of the first local relative to fp */
162 void i_prolog(int argc, int varg, int sargs, int sregs, int initfp, int subsp);
163 void i_epilog(int sp_max);
164 void i_done(void);
166 extern int tmpregs[];
167 extern int argregs[];
169 /* code segment text */
170 extern char cs[]; /* code segment */
171 extern int cslen; /* code segment length */
172 extern int pass1; /* first pass */
174 void os(void *s, int n);
175 void oi(long n, int l);