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ShaderPlayground / deps / luajit / include / lj_emit_arm.h
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1/*
2** ARM instruction emitter.
3** Copyright (C) 2005-2026 Mike Pall. See Copyright Notice in luajit.h
4*/
5
6/* -- Constant encoding --------------------------------------------------- */
7
8static uint8_t emit_invai[16] = {
9 /* AND */ (ARMI_AND^ARMI_BIC) >> 21,
10 /* EOR */ 0,
11 /* SUB */ (ARMI_SUB^ARMI_ADD) >> 21,
12 /* RSB */ 0,
13 /* ADD */ (ARMI_ADD^ARMI_SUB) >> 21,
14 /* ADC */ (ARMI_ADC^ARMI_SBC) >> 21,
15 /* SBC */ (ARMI_SBC^ARMI_ADC) >> 21,
16 /* RSC */ 0,
17 /* TST */ 0,
18 /* TEQ */ 0,
19 /* CMP */ (ARMI_CMP^ARMI_CMN) >> 21,
20 /* CMN */ (ARMI_CMN^ARMI_CMP) >> 21,
21 /* ORR */ 0,
22 /* MOV */ (ARMI_MOV^ARMI_MVN) >> 21,
23 /* BIC */ (ARMI_BIC^ARMI_AND) >> 21,
24 /* MVN */ (ARMI_MVN^ARMI_MOV) >> 21
25};
26
27/* Encode constant in K12 format for data processing instructions. */
28static uint32_t emit_isk12(ARMIns ai, int32_t n)
29{
30 uint32_t invai, i, m = (uint32_t)n;
31 /* K12: unsigned 8 bit value, rotated in steps of two bits. */
32 for (i = 0; i < 4096; i += 256, m = lj_rol(m, 2))
33 if (m <= 255) return ARMI_K12|m|i;
34 /* Otherwise try negation/complement with the inverse instruction. */
35 invai = emit_invai[((ai >> 21) & 15)];
36 if (!invai) return 0; /* Failed. No inverse instruction. */
37 m = ~(uint32_t)n;
38 if (invai == ((ARMI_SUB^ARMI_ADD) >> 21) ||
39 invai == (ARMI_CMP^ARMI_CMN) >> 21) m++;
40 for (i = 0; i < 4096; i += 256, m = lj_rol(m, 2))
41 if (m <= 255) return ARMI_K12|(invai<<21)|m|i;
42 return 0; /* Failed. */
43}
44
45/* -- Emit basic instructions --------------------------------------------- */
46
47static void emit_dnm(ASMState *as, ARMIns ai, Reg rd, Reg rn, Reg rm)
48{
49 *--as->mcp = ai | ARMF_D(rd) | ARMF_N(rn) | ARMF_M(rm);
50}
51
52static void emit_dm(ASMState *as, ARMIns ai, Reg rd, Reg rm)
53{
54 *--as->mcp = ai | ARMF_D(rd) | ARMF_M(rm);
55}
56
57static void emit_dn(ASMState *as, ARMIns ai, Reg rd, Reg rn)
58{
59 *--as->mcp = ai | ARMF_D(rd) | ARMF_N(rn);
60}
61
62static void emit_nm(ASMState *as, ARMIns ai, Reg rn, Reg rm)
63{
64 *--as->mcp = ai | ARMF_N(rn) | ARMF_M(rm);
65}
66
67static void emit_d(ASMState *as, ARMIns ai, Reg rd)
68{
69 *--as->mcp = ai | ARMF_D(rd);
70}
71
72static void emit_n(ASMState *as, ARMIns ai, Reg rn)
73{
74 *--as->mcp = ai | ARMF_N(rn);
75}
76
77static void emit_m(ASMState *as, ARMIns ai, Reg rm)
78{
79 *--as->mcp = ai | ARMF_M(rm);
80}
81
82static void emit_lsox(ASMState *as, ARMIns ai, Reg rd, Reg rn, int32_t ofs)
83{
84 lua_assert(ofs >= -255 && ofs <= 255);
85 if (ofs < 0) ofs = -ofs; else ai |= ARMI_LS_U;
86 *--as->mcp = ai | ARMI_LS_P | ARMI_LSX_I | ARMF_D(rd) | ARMF_N(rn) |
87 ((ofs & 0xf0) << 4) | (ofs & 0x0f);
88}
89
90static void emit_lso(ASMState *as, ARMIns ai, Reg rd, Reg rn, int32_t ofs)
91{
92 lua_assert(ofs >= -4095 && ofs <= 4095);
93 /* Combine LDR/STR pairs to LDRD/STRD. */
94 if (*as->mcp == (ai|ARMI_LS_P|ARMI_LS_U|ARMF_D(rd^1)|ARMF_N(rn)|(ofs^4)) &&
95 (ai & ~(ARMI_LDR^ARMI_STR)) == ARMI_STR && rd != rn &&
96 (uint32_t)ofs <= 252 && !(ofs & 3) && !((rd ^ (ofs >>2)) & 1) &&
97 as->mcp != as->mcloop) {
98 as->mcp++;
99 emit_lsox(as, ai == ARMI_LDR ? ARMI_LDRD : ARMI_STRD, rd&~1, rn, ofs&~4);
100 return;
101 }
102 if (ofs < 0) ofs = -ofs; else ai |= ARMI_LS_U;
103 *--as->mcp = ai | ARMI_LS_P | ARMF_D(rd) | ARMF_N(rn) | ofs;
104}
105
106#if !LJ_SOFTFP
107static void emit_vlso(ASMState *as, ARMIns ai, Reg rd, Reg rn, int32_t ofs)
108{
109 lua_assert(ofs >= -1020 && ofs <= 1020 && (ofs&3) == 0);
110 if (ofs < 0) ofs = -ofs; else ai |= ARMI_LS_U;
111 *--as->mcp = ai | ARMI_LS_P | ARMF_D(rd & 15) | ARMF_N(rn) | (ofs >> 2);
112}
113#endif
114
115/* -- Emit loads/stores --------------------------------------------------- */
116
117/* Prefer spills of BASE/L. */
118#define emit_canremat(ref) ((ref) < ASMREF_L)
119
120/* Try to find a one step delta relative to another constant. */
121static int emit_kdelta1(ASMState *as, Reg d, int32_t i)
122{
123 RegSet work = ~as->freeset & RSET_GPR;
124 while (work) {
125 Reg r = rset_picktop(work);
126 IRRef ref = regcost_ref(as->cost[r]);
127 lua_assert(r != d);
128 if (emit_canremat(ref)) {
129 int32_t delta = i - (ra_iskref(ref) ? ra_krefk(as, ref) : IR(ref)->i);
130 uint32_t k = emit_isk12(ARMI_ADD, delta);
131 if (k) {
132 if (k == ARMI_K12)
133 emit_dm(as, ARMI_MOV, d, r);
134 else
135 emit_dn(as, ARMI_ADD^k, d, r);
136 return 1;
137 }
138 }
139 rset_clear(work, r);
140 }
141 return 0; /* Failed. */
142}
143
144/* Try to find a two step delta relative to another constant. */
145static int emit_kdelta2(ASMState *as, Reg d, int32_t i)
146{
147 RegSet work = ~as->freeset & RSET_GPR;
148 while (work) {
149 Reg r = rset_picktop(work);
150 IRRef ref = regcost_ref(as->cost[r]);
151 lua_assert(r != d);
152 if (emit_canremat(ref)) {
153 int32_t other = ra_iskref(ref) ? ra_krefk(as, ref) : IR(ref)->i;
154 if (other) {
155 int32_t delta = i - other;
156 uint32_t sh, inv = 0, k2, k;
157 if (delta < 0) { delta = (int32_t)(~(uint32_t)delta+1u); inv = ARMI_ADD^ARMI_SUB; }
158 sh = lj_ffs(delta) & ~1;
159 k2 = emit_isk12(0, delta & (255 << sh));
160 k = emit_isk12(0, delta & ~(255 << sh));
161 if (k) {
162 emit_dn(as, ARMI_ADD^k2^inv, d, d);
163 emit_dn(as, ARMI_ADD^k^inv, d, r);
164 return 1;
165 }
166 }
167 }
168 rset_clear(work, r);
169 }
170 return 0; /* Failed. */
171}
172
173/* Load a 32 bit constant into a GPR. */
174static void emit_loadi(ASMState *as, Reg r, int32_t i)
175{
176 uint32_t k = emit_isk12(ARMI_MOV, i);
177 lua_assert(rset_test(as->freeset, r) || r == RID_TMP);
178 if (k) {
179 /* Standard K12 constant. */
180 emit_d(as, ARMI_MOV^k, r);
181 } else if ((as->flags & JIT_F_ARMV6T2) && (uint32_t)i < 0x00010000u) {
182 /* 16 bit loword constant for ARMv6T2. */
183 emit_d(as, ARMI_MOVW|(i & 0x0fff)|((i & 0xf000)<<4), r);
184 } else if (emit_kdelta1(as, r, i)) {
185 /* One step delta relative to another constant. */
186 } else if ((as->flags & JIT_F_ARMV6T2)) {
187 /* 32 bit hiword/loword constant for ARMv6T2. */
188 emit_d(as, ARMI_MOVT|((i>>16) & 0x0fff)|(((i>>16) & 0xf000)<<4), r);
189 emit_d(as, ARMI_MOVW|(i & 0x0fff)|((i & 0xf000)<<4), r);
190 } else if (emit_kdelta2(as, r, i)) {
191 /* Two step delta relative to another constant. */
192 } else {
193 /* Otherwise construct the constant with up to 4 instructions. */
194 /* NYI: use mvn+bic, use pc-relative loads. */
195 for (;;) {
196 uint32_t sh = lj_ffs(i) & ~1;
197 int32_t m = i & (255 << sh);
198 i &= ~(255 << sh);
199 if (i == 0) {
200 emit_d(as, ARMI_MOV ^ emit_isk12(0, m), r);
201 break;
202 }
203 emit_dn(as, ARMI_ORR ^ emit_isk12(0, m), r, r);
204 }
205 }
206}
207
208#define emit_loada(as, r, addr) emit_loadi(as, (r), i32ptr((addr)))
209
210static Reg ra_allock(ASMState *as, int32_t k, RegSet allow);
211
212/* Get/set from constant pointer. */
213static void emit_lsptr(ASMState *as, ARMIns ai, Reg r, void *p)
214{
215 int32_t i = i32ptr(p);
216 emit_lso(as, ai, r, ra_allock(as, (i & ~4095), rset_exclude(RSET_GPR, r)),
217 (i & 4095));
218}
219
220#if !LJ_SOFTFP
221/* Load a number constant into an FPR. */
222static void emit_loadn(ASMState *as, Reg r, cTValue *tv)
223{
224 int32_t i;
225 if ((as->flags & JIT_F_VFPV3) && !tv->u32.lo) {
226 uint32_t hi = tv->u32.hi;
227 uint32_t b = ((hi >> 22) & 0x1ff);
228 if (!(hi & 0xffff) && (b == 0x100 || b == 0x0ff)) {
229 *--as->mcp = ARMI_VMOVI_D | ARMF_D(r & 15) |
230 ((tv->u32.hi >> 12) & 0x00080000) |
231 ((tv->u32.hi >> 4) & 0x00070000) |
232 ((tv->u32.hi >> 16) & 0x0000000f);
233 return;
234 }
235 }
236 i = i32ptr(tv);
237 emit_vlso(as, ARMI_VLDR_D, r,
238 ra_allock(as, (i & ~1020), RSET_GPR), (i & 1020));
239}
240#endif
241
242/* Get/set global_State fields. */
243#define emit_getgl(as, r, field) \
244 emit_lsptr(as, ARMI_LDR, (r), (void *)&J2G(as->J)->field)
245#define emit_setgl(as, r, field) \
246 emit_lsptr(as, ARMI_STR, (r), (void *)&J2G(as->J)->field)
247
248/* Trace number is determined from pc of exit instruction. */
249#define emit_setvmstate(as, i) UNUSED(i)
250
251/* -- Emit control-flow instructions -------------------------------------- */
252
253/* Label for internal jumps. */
254typedef MCode *MCLabel;
255
256/* Return label pointing to current PC. */
257#define emit_label(as) ((as)->mcp)
258
259static void emit_branch(ASMState *as, ARMIns ai, MCode *target)
260{
261 MCode *p = as->mcp;
262 ptrdiff_t delta = (target - p) - 1;
263 lua_assert(((delta + 0x00800000) >> 24) == 0);
264 *--p = ai | ((uint32_t)delta & 0x00ffffffu);
265 as->mcp = p;
266}
267
268#define emit_jmp(as, target) emit_branch(as, ARMI_B, (target))
269
270static void emit_call(ASMState *as, void *target)
271{
272 MCode *p = --as->mcp;
273 ptrdiff_t delta = ((char *)target - (char *)p) - 8;
274 if ((((delta>>2) + 0x00800000) >> 24) == 0) {
275 if ((delta & 1))
276 *p = ARMI_BLX | ((uint32_t)(delta>>2) & 0x00ffffffu) | ((delta&2) << 23);
277 else
278 *p = ARMI_BL | ((uint32_t)(delta>>2) & 0x00ffffffu);
279 } else { /* Target out of range: need indirect call. But don't use R0-R3. */
280 Reg r = ra_allock(as, i32ptr(target), RSET_RANGE(RID_R4, RID_R12+1));
281 *p = ARMI_BLXr | ARMF_M(r);
282 }
283}
284
285/* -- Emit generic operations --------------------------------------------- */
286
287/* Generic move between two regs. */
288static void emit_movrr(ASMState *as, IRIns *ir, Reg dst, Reg src)
289{
290#if LJ_SOFTFP
291 lua_assert(!irt_isnum(ir->t)); UNUSED(ir);
292#else
293 if (dst >= RID_MAX_GPR) {
294 emit_dm(as, irt_isnum(ir->t) ? ARMI_VMOV_D : ARMI_VMOV_S,
295 (dst & 15), (src & 15));
296 return;
297 }
298#endif
299 if (as->mcp != as->mcloop) { /* Swap early registers for loads/stores. */
300 MCode ins = *as->mcp, swp = (src^dst);
301 if ((ins & 0x0c000000) == 0x04000000 && (ins & 0x02000010) != 0x02000010) {
302 if (!((ins ^ (dst << 16)) & 0x000f0000))
303 *as->mcp = ins ^ (swp << 16); /* Swap N in load/store. */
304 if (!(ins & 0x00100000) && !((ins ^ (dst << 12)) & 0x0000f000))
305 *as->mcp = ins ^ (swp << 12); /* Swap D in store. */
306 }
307 }
308 emit_dm(as, ARMI_MOV, dst, src);
309}
310
311/* Generic load of register from stack slot. */
312static void emit_spload(ASMState *as, IRIns *ir, Reg r, int32_t ofs)
313{
314#if LJ_SOFTFP
315 lua_assert(!irt_isnum(ir->t)); UNUSED(ir);
316#else
317 if (r >= RID_MAX_GPR)
318 emit_vlso(as, irt_isnum(ir->t) ? ARMI_VLDR_D : ARMI_VLDR_S, r, RID_SP, ofs);
319 else
320#endif
321 emit_lso(as, ARMI_LDR, r, RID_SP, ofs);
322}
323
324/* Generic store of register to stack slot. */
325static void emit_spstore(ASMState *as, IRIns *ir, Reg r, int32_t ofs)
326{
327#if LJ_SOFTFP
328 lua_assert(!irt_isnum(ir->t)); UNUSED(ir);
329#else
330 if (r >= RID_MAX_GPR)
331 emit_vlso(as, irt_isnum(ir->t) ? ARMI_VSTR_D : ARMI_VSTR_S, r, RID_SP, ofs);
332 else
333#endif
334 emit_lso(as, ARMI_STR, r, RID_SP, ofs);
335}
336
337/* Emit an arithmetic/logic operation with a constant operand. */
338static void emit_opk(ASMState *as, ARMIns ai, Reg dest, Reg src,
339 int32_t i, RegSet allow)
340{
341 uint32_t k = emit_isk12(ai, i);
342 if (k)
343 emit_dn(as, ai^k, dest, src);
344 else
345 emit_dnm(as, ai, dest, src, ra_allock(as, i, allow));
346}
347
348/* Add offset to pointer. */
349static void emit_addptr(ASMState *as, Reg r, int32_t ofs)
350{
351 if (ofs)
352 emit_opk(as, ARMI_ADD, r, r, ofs, rset_exclude(RSET_GPR, r));
353}
354
355#define emit_spsub(as, ofs) emit_addptr(as, RID_SP, -(ofs))
356