--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/luajit/dynasm/dasm_x86.h	Thu Jan 22 20:10:30 2026 -0800
@@ -0,0 +1,523 @@
+/*
+** DynASM x86 encoding engine.
+** Copyright (C) 2005-2023 Mike Pall. All rights reserved.
+** Released under the MIT license. See dynasm.lua for full copyright notice.
+*/
+
+#include <stddef.h>
+#include <stdarg.h>
+#include <string.h>
+#include <stdlib.h>
+
+#define DASM_ARCH		"x86"
+
+#ifndef DASM_EXTERN
+#define DASM_EXTERN(a,b,c,d)	0
+#endif
+
+/* Action definitions. DASM_STOP must be 255. */
+enum {
+  DASM_DISP = 233,
+  DASM_IMM_S, DASM_IMM_B, DASM_IMM_W, DASM_IMM_D, DASM_IMM_WB, DASM_IMM_DB,
+  DASM_VREG, DASM_SPACE, DASM_SETLABEL, DASM_REL_A, DASM_REL_LG, DASM_REL_PC,
+  DASM_IMM_LG, DASM_IMM_PC, DASM_LABEL_LG, DASM_LABEL_PC, DASM_ALIGN,
+  DASM_EXTERN, DASM_ESC, DASM_MARK, DASM_SECTION, DASM_STOP
+};
+
+/* Maximum number of section buffer positions for a single dasm_put() call. */
+#define DASM_MAXSECPOS		25
+
+/* DynASM encoder status codes. Action list offset or number are or'ed in. */
+#define DASM_S_OK		0x00000000
+#define DASM_S_NOMEM		0x01000000
+#define DASM_S_PHASE		0x02000000
+#define DASM_S_MATCH_SEC	0x03000000
+#define DASM_S_RANGE_I		0x11000000
+#define DASM_S_RANGE_SEC	0x12000000
+#define DASM_S_RANGE_LG		0x13000000
+#define DASM_S_RANGE_PC		0x14000000
+#define DASM_S_RANGE_VREG	0x15000000
+#define DASM_S_UNDEF_L		0x21000000
+#define DASM_S_UNDEF_PC		0x22000000
+
+/* Macros to convert positions (8 bit section + 24 bit index). */
+#define DASM_POS2IDX(pos)	((pos)&0x00ffffff)
+#define DASM_POS2BIAS(pos)	((pos)&0xff000000)
+#define DASM_SEC2POS(sec)	((sec)<<24)
+#define DASM_POS2SEC(pos)	((pos)>>24)
+#define DASM_POS2PTR(D, pos)	(D->sections[DASM_POS2SEC(pos)].rbuf + (pos))
+
+/* Action list type. */
+typedef const unsigned char *dasm_ActList;
+
+/* Per-section structure. */
+typedef struct dasm_Section {
+  int *rbuf;		/* Biased buffer pointer (negative section bias). */
+  int *buf;		/* True buffer pointer. */
+  size_t bsize;		/* Buffer size in bytes. */
+  int pos;		/* Biased buffer position. */
+  int epos;		/* End of biased buffer position - max single put. */
+  int ofs;		/* Byte offset into section. */
+} dasm_Section;
+
+/* Core structure holding the DynASM encoding state. */
+struct dasm_State {
+  size_t psize;			/* Allocated size of this structure. */
+  dasm_ActList actionlist;	/* Current actionlist pointer. */
+  int *lglabels;		/* Local/global chain/pos ptrs. */
+  size_t lgsize;
+  int *pclabels;		/* PC label chains/pos ptrs. */
+  size_t pcsize;
+  void **globals;		/* Array of globals. */
+  dasm_Section *section;	/* Pointer to active section. */
+  size_t codesize;		/* Total size of all code sections. */
+  int maxsection;		/* 0 <= sectionidx < maxsection. */
+  int status;			/* Status code. */
+  dasm_Section sections[1];	/* All sections. Alloc-extended. */
+};
+
+/* The size of the core structure depends on the max. number of sections. */
+#define DASM_PSZ(ms)	(sizeof(dasm_State)+(ms-1)*sizeof(dasm_Section))
+
+
+/* Initialize DynASM state. */
+void dasm_init(Dst_DECL, int maxsection)
+{
+  dasm_State *D;
+  size_t psz = 0;
+  Dst_REF = NULL;
+  DASM_M_GROW(Dst, struct dasm_State, Dst_REF, psz, DASM_PSZ(maxsection));
+  D = Dst_REF;
+  D->psize = psz;
+  D->lglabels = NULL;
+  D->lgsize = 0;
+  D->pclabels = NULL;
+  D->pcsize = 0;
+  D->globals = NULL;
+  D->maxsection = maxsection;
+  memset((void *)D->sections, 0, maxsection * sizeof(dasm_Section));
+}
+
+/* Free DynASM state. */
+void dasm_free(Dst_DECL)
+{
+  dasm_State *D = Dst_REF;
+  int i;
+  for (i = 0; i < D->maxsection; i++)
+    if (D->sections[i].buf)
+      DASM_M_FREE(Dst, D->sections[i].buf, D->sections[i].bsize);
+  if (D->pclabels) DASM_M_FREE(Dst, D->pclabels, D->pcsize);
+  if (D->lglabels) DASM_M_FREE(Dst, D->lglabels, D->lgsize);
+  DASM_M_FREE(Dst, D, D->psize);
+}
+
+/* Setup global label array. Must be called before dasm_setup(). */
+void dasm_setupglobal(Dst_DECL, void **gl, unsigned int maxgl)
+{
+  dasm_State *D = Dst_REF;
+  D->globals = gl;
+  DASM_M_GROW(Dst, int, D->lglabels, D->lgsize, (10+maxgl)*sizeof(int));
+}
+
+/* Grow PC label array. Can be called after dasm_setup(), too. */
+void dasm_growpc(Dst_DECL, unsigned int maxpc)
+{
+  dasm_State *D = Dst_REF;
+  size_t osz = D->pcsize;
+  DASM_M_GROW(Dst, int, D->pclabels, D->pcsize, maxpc*sizeof(int));
+  memset((void *)(((unsigned char *)D->pclabels)+osz), 0, D->pcsize-osz);
+}
+
+/* Setup encoder. */
+void dasm_setup(Dst_DECL, const void *actionlist)
+{
+  dasm_State *D = Dst_REF;
+  int i;
+  D->actionlist = (dasm_ActList)actionlist;
+  D->status = DASM_S_OK;
+  D->section = &D->sections[0];
+  memset((void *)D->lglabels, 0, D->lgsize);
+  if (D->pclabels) memset((void *)D->pclabels, 0, D->pcsize);
+  for (i = 0; i < D->maxsection; i++) {
+    D->sections[i].pos = DASM_SEC2POS(i);
+    D->sections[i].rbuf = D->sections[i].buf - D->sections[i].pos;
+    D->sections[i].ofs = 0;
+  }
+}
+
+
+#ifdef DASM_CHECKS
+#define CK(x, st) \
+  do { if (!(x)) { \
+    D->status = DASM_S_##st|(int)(p-D->actionlist-1); return; } } while (0)
+#define CKPL(kind, st) \
+  do { if ((size_t)((char *)pl-(char *)D->kind##labels) >= D->kind##size) { \
+    D->status=DASM_S_RANGE_##st|(int)(p-D->actionlist-1); return; } } while (0)
+#else
+#define CK(x, st)	((void)0)
+#define CKPL(kind, st)	((void)0)
+#endif
+
+/* Pass 1: Store actions and args, link branches/labels, estimate offsets. */
+void dasm_put(Dst_DECL, int start, ...)
+{
+  va_list ap;
+  dasm_State *D = Dst_REF;
+  dasm_ActList p = D->actionlist + start;
+  dasm_Section *sec = D->section;
+  int pos = sec->pos, ofs = sec->ofs, mrm = -1;
+  int *b;
+
+  if (pos >= sec->epos) {
+    DASM_M_GROW(Dst, int, sec->buf, sec->bsize,
+      sec->bsize + 2*DASM_MAXSECPOS*sizeof(int));
+    sec->rbuf = sec->buf - DASM_POS2BIAS(pos);
+    sec->epos = (int)sec->bsize/sizeof(int) - DASM_MAXSECPOS+DASM_POS2BIAS(pos);
+  }
+
+  b = sec->rbuf;
+  b[pos++] = start;
+
+  va_start(ap, start);
+  while (1) {
+    int action = *p++;
+    if (action < DASM_DISP) {
+      ofs++;
+    } else if (action <= DASM_REL_A) {
+      int n = va_arg(ap, int);
+      b[pos++] = n;
+      switch (action) {
+      case DASM_DISP:
+	if (n == 0) { if (mrm < 0) mrm = p[-2]; if ((mrm&7) != 5) break; }
+	/* fallthrough */
+      case DASM_IMM_DB: if (((n+128)&-256) == 0) goto ob; /* fallthrough */
+      case DASM_REL_A: /* Assumes ptrdiff_t is int. !x64 */
+      case DASM_IMM_D: ofs += 4; break;
+      case DASM_IMM_S: CK(((n+128)&-256) == 0, RANGE_I); goto ob;
+      case DASM_IMM_B: CK((n&-256) == 0, RANGE_I); ob: ofs++; break;
+      case DASM_IMM_WB: if (((n+128)&-256) == 0) goto ob; /* fallthrough */
+      case DASM_IMM_W: CK((n&-65536) == 0, RANGE_I); ofs += 2; break;
+      case DASM_SPACE: p++; ofs += n; break;
+      case DASM_SETLABEL: b[pos-2] = -0x40000000; break;  /* Neg. label ofs. */
+      case DASM_VREG: CK((n&-16) == 0 && (n != 4 || (*p>>5) != 2), RANGE_VREG);
+	if (*p < 0x40 && p[1] == DASM_DISP) mrm = n;
+	if (*p < 0x20 && (n&7) == 4) ofs++;
+	switch ((*p++ >> 3) & 3) {
+	case 3: n |= b[pos-3]; /* fallthrough */
+	case 2: n |= b[pos-2]; /* fallthrough */
+	case 1: if (n <= 7) { b[pos-1] |= 0x10; ofs--; }
+	}
+	continue;
+      }
+      mrm = -1;
+    } else {
+      int *pl, n;
+      switch (action) {
+      case DASM_REL_LG:
+      case DASM_IMM_LG:
+	n = *p++; pl = D->lglabels + n;
+	/* Bkwd rel or global. */
+	if (n <= 246) { CK(n>=10||*pl<0, RANGE_LG); CKPL(lg, LG); goto putrel; }
+	pl -= 246; n = *pl;
+	if (n < 0) n = 0;  /* Start new chain for fwd rel if label exists. */
+	goto linkrel;
+      case DASM_REL_PC:
+      case DASM_IMM_PC: pl = D->pclabels + va_arg(ap, int); CKPL(pc, PC);
+      putrel:
+	n = *pl;
+	if (n < 0) {  /* Label exists. Get label pos and store it. */
+	  b[pos] = -n;
+	} else {
+      linkrel:
+	  b[pos] = n;  /* Else link to rel chain, anchored at label. */
+	  *pl = pos;
+	}
+	pos++;
+	ofs += 4;  /* Maximum offset needed. */
+	if (action == DASM_REL_LG || action == DASM_REL_PC) {
+	  b[pos++] = ofs;  /* Store pass1 offset estimate. */
+	} else if (sizeof(ptrdiff_t) == 8) {
+	  ofs += 4;
+	}
+	break;
+      case DASM_LABEL_LG: pl = D->lglabels + *p++; CKPL(lg, LG); goto putlabel;
+      case DASM_LABEL_PC: pl = D->pclabels + va_arg(ap, int); CKPL(pc, PC);
+      putlabel:
+	n = *pl;  /* n > 0: Collapse rel chain and replace with label pos. */
+	while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = pos; }
+	*pl = -pos;  /* Label exists now. */
+	b[pos++] = ofs;  /* Store pass1 offset estimate. */
+	break;
+      case DASM_ALIGN:
+	ofs += *p++;  /* Maximum alignment needed (arg is 2**n-1). */
+	b[pos++] = ofs;  /* Store pass1 offset estimate. */
+	break;
+      case DASM_EXTERN: p += 2; ofs += 4; break;
+      case DASM_ESC: p++; ofs++; break;
+      case DASM_MARK: mrm = p[-2]; break;
+      case DASM_SECTION:
+	n = *p; CK(n < D->maxsection, RANGE_SEC); D->section = &D->sections[n];
+      case DASM_STOP: goto stop;
+      }
+    }
+  }
+stop:
+  va_end(ap);
+  sec->pos = pos;
+  sec->ofs = ofs;
+}
+#undef CK
+
+/* Pass 2: Link sections, shrink branches/aligns, fix label offsets. */
+int dasm_link(Dst_DECL, size_t *szp)
+{
+  dasm_State *D = Dst_REF;
+  int secnum;
+  int ofs = 0;
+
+#ifdef DASM_CHECKS
+  *szp = 0;
+  if (D->status != DASM_S_OK) return D->status;
+  {
+    int pc;
+    for (pc = 0; pc*sizeof(int) < D->pcsize; pc++)
+      if (D->pclabels[pc] > 0) return DASM_S_UNDEF_PC|pc;
+  }
+#endif
+
+  { /* Handle globals not defined in this translation unit. */
+    int idx;
+    for (idx = 10; idx*sizeof(int) < D->lgsize; idx++) {
+      int n = D->lglabels[idx];
+      /* Undefined label: Collapse rel chain and replace with marker (< 0). */
+      while (n > 0) { int *pb = DASM_POS2PTR(D, n); n = *pb; *pb = -idx; }
+    }
+  }
+
+  /* Combine all code sections. No support for data sections (yet). */
+  for (secnum = 0; secnum < D->maxsection; secnum++) {
+    dasm_Section *sec = D->sections + secnum;
+    int *b = sec->rbuf;
+    int pos = DASM_SEC2POS(secnum);
+    int lastpos = sec->pos;
+
+    while (pos != lastpos) {
+      dasm_ActList p = D->actionlist + b[pos++];
+      int op = 0;
+      while (1) {
+	int action = *p++;
+	switch (action) {
+	case DASM_REL_LG: p++;
+	  /* fallthrough */
+	case DASM_REL_PC: {
+	  int shrink = op == 0xe9 ? 3 : ((op&0xf0) == 0x80 ? 4 : 0);
+	  if (shrink) {  /* Shrinkable branch opcode? */
+	    int lofs, lpos = b[pos];
+	    if (lpos < 0) goto noshrink;  /* Ext global? */
+	    lofs = *DASM_POS2PTR(D, lpos);
+	    if (lpos > pos) {  /* Fwd label: add cumulative section offsets. */
+	      int i;
+	      for (i = secnum; i < DASM_POS2SEC(lpos); i++)
+		lofs += D->sections[i].ofs;
+	    } else {
+	      lofs -= ofs;  /* Bkwd label: unfix offset. */
+	    }
+	    lofs -= b[pos+1];  /* Short branch ok? */
+	    if (lofs >= -128-shrink && lofs <= 127) ofs -= shrink;  /* Yes. */
+	    else { noshrink: shrink = 0; }  /* No, cannot shrink op. */
+	  }
+	  b[pos+1] = shrink;
+	  pos += 2;
+	  break;
+	}
+	  /* fallthrough */
+	case DASM_SPACE: case DASM_IMM_LG: case DASM_VREG: p++;
+	  /* fallthrough */
+	case DASM_DISP: case DASM_IMM_S: case DASM_IMM_B: case DASM_IMM_W:
+	case DASM_IMM_D: case DASM_IMM_WB: case DASM_IMM_DB:
+	case DASM_SETLABEL: case DASM_REL_A: case DASM_IMM_PC: pos++; break;
+	case DASM_LABEL_LG: p++;
+	  /* fallthrough */
+	case DASM_LABEL_PC: b[pos++] += ofs; break; /* Fix label offset. */
+	case DASM_ALIGN: ofs -= (b[pos++]+ofs)&*p++; break; /* Adjust ofs. */
+	case DASM_EXTERN: p += 2; break;
+	case DASM_ESC: op = *p++; break;
+	case DASM_MARK: break;
+	case DASM_SECTION: case DASM_STOP: goto stop;
+	default: op = action; break;
+	}
+      }
+      stop: (void)0;
+    }
+    ofs += sec->ofs;  /* Next section starts right after current section. */
+  }
+
+  D->codesize = ofs;  /* Total size of all code sections */
+  *szp = ofs;
+  return DASM_S_OK;
+}
+
+#define dasmb(x)	*cp++ = (unsigned char)(x)
+#ifndef DASM_ALIGNED_WRITES
+#define dasmw(x) \
+  do { *((unsigned short *)cp) = (unsigned short)(x); cp+=2; } while (0)
+#define dasmd(x) \
+  do { *((unsigned int *)cp) = (unsigned int)(x); cp+=4; } while (0)
+#define dasmq(x) \
+  do { *((unsigned long long *)cp) = (unsigned long long)(x); cp+=8; } while (0)
+#else
+#define dasmw(x)	do { dasmb(x); dasmb((x)>>8); } while (0)
+#define dasmd(x)	do { dasmw(x); dasmw((x)>>16); } while (0)
+#define dasmq(x)	do { dasmd(x); dasmd((x)>>32); } while (0)
+#endif
+static unsigned char *dasma_(unsigned char *cp, ptrdiff_t x)
+{
+  if (sizeof(ptrdiff_t) == 8)
+    dasmq((unsigned long long)x);
+  else
+    dasmd((unsigned int)x);
+  return cp;
+}
+#define dasma(x)	(cp = dasma_(cp, (x)))
+
+/* Pass 3: Encode sections. */
+int dasm_encode(Dst_DECL, void *buffer)
+{
+  dasm_State *D = Dst_REF;
+  unsigned char *base = (unsigned char *)buffer;
+  unsigned char *cp = base;
+  int secnum;
+
+  /* Encode all code sections. No support for data sections (yet). */
+  for (secnum = 0; secnum < D->maxsection; secnum++) {
+    dasm_Section *sec = D->sections + secnum;
+    int *b = sec->buf;
+    int *endb = sec->rbuf + sec->pos;
+
+    while (b != endb) {
+      dasm_ActList p = D->actionlist + *b++;
+      unsigned char *mark = NULL;
+      while (1) {
+	int action = *p++;
+	int n = (action >= DASM_DISP && action <= DASM_ALIGN) ? *b++ : 0;
+	switch (action) {
+	case DASM_DISP: if (!mark) mark = cp; {
+	  unsigned char *mm = mark;
+	  if (*p != DASM_IMM_DB && *p != DASM_IMM_WB) mark = NULL;
+	  if (n == 0) { int mrm = mm[-1]&7; if (mrm == 4) mrm = mm[0]&7;
+	    if (mrm != 5) { mm[-1] -= 0x80; break; } }
+	  if (((n+128) & -256) != 0) goto wd; else mm[-1] -= 0x40;
+	}
+	  /* fallthrough */
+	case DASM_IMM_S: case DASM_IMM_B: wb: dasmb(n); break;
+	case DASM_IMM_DB: if (((n+128)&-256) == 0) {
+	    db: if (!mark) mark = cp; mark[-2] += 2; mark = NULL; goto wb;
+	  } else mark = NULL;
+	  /* fallthrough */
+	case DASM_IMM_D: wd: dasmd(n); break;
+	case DASM_IMM_WB: if (((n+128)&-256) == 0) goto db; else mark = NULL;
+	  /* fallthrough */
+	case DASM_IMM_W: dasmw(n); break;
+	case DASM_VREG: {
+	  int t = *p++;
+	  unsigned char *ex = cp - (t&7);
+	  if ((n & 8) && t < 0xa0) {
+	    if (*ex & 0x80) ex[1] ^= 0x20 << (t>>6); else *ex ^= 1 << (t>>6);
+	    n &= 7;
+	  } else if (n & 0x10) {
+	    if (*ex & 0x80) {
+	      *ex = 0xc5; ex[1] = (ex[1] & 0x80) | ex[2]; ex += 2;
+	    }
+	    while (++ex < cp) ex[-1] = *ex;
+	    if (mark) mark--;
+	    cp--;
+	    n &= 7;
+	  }
+	  if (t >= 0xc0) n <<= 4;
+	  else if (t >= 0x40) n <<= 3;
+	  else if (n == 4 && t < 0x20) { cp[-1] ^= n; *cp++ = 0x20; }
+	  cp[-1] ^= n;
+	  break;
+	}
+	case DASM_REL_LG: p++; if (n >= 0) goto rel_pc;
+	  b++; n = (int)(ptrdiff_t)D->globals[-n-10];
+	  /* fallthrough */
+	case DASM_REL_A: rel_a:
+	  n -= (unsigned int)(ptrdiff_t)(cp+4); goto wd; /* !x64 */
+	case DASM_REL_PC: rel_pc: {
+	  int shrink = *b++;
+	  int *pb = DASM_POS2PTR(D, n); if (*pb < 0) { n = pb[1]; goto rel_a; }
+	  n = *pb - ((int)(cp-base) + 4-shrink);
+	  if (shrink == 0) goto wd;
+	  if (shrink == 4) { cp--; cp[-1] = *cp-0x10; } else cp[-1] = 0xeb;
+	  goto wb;
+	}
+	case DASM_IMM_LG:
+	  p++;
+	  if (n < 0) { dasma((ptrdiff_t)D->globals[-n-10]); break; }
+	  /* fallthrough */
+	case DASM_IMM_PC: {
+	  int *pb = DASM_POS2PTR(D, n);
+	  dasma(*pb < 0 ? (ptrdiff_t)pb[1] : (*pb + (ptrdiff_t)base));
+	  break;
+	}
+	case DASM_LABEL_LG: {
+	  int idx = *p++;
+	  if (idx >= 10)
+	    D->globals[idx-10] = (void *)(base + (*p == DASM_SETLABEL ? *b : n));
+	  break;
+	}
+	case DASM_LABEL_PC: case DASM_SETLABEL: break;
+	case DASM_SPACE: { int fill = *p++; while (n--) *cp++ = fill; break; }
+	case DASM_ALIGN:
+	  n = *p++;
+	  while (((cp-base) & n)) *cp++ = 0x90; /* nop */
+	  break;
+	case DASM_EXTERN: n = DASM_EXTERN(Dst, cp, p[1], *p); p += 2; goto wd;
+	case DASM_MARK: mark = cp; break;
+	case DASM_ESC: action = *p++;
+	  /* fallthrough */
+	default: *cp++ = action; break;
+	case DASM_SECTION: case DASM_STOP: goto stop;
+	}
+      }
+      stop: (void)0;
+    }
+  }
+
+  if (base + D->codesize != cp)  /* Check for phase errors. */
+    return DASM_S_PHASE;
+  return DASM_S_OK;
+}
+
+/* Get PC label offset. */
+int dasm_getpclabel(Dst_DECL, unsigned int pc)
+{
+  dasm_State *D = Dst_REF;
+  if (pc*sizeof(int) < D->pcsize) {
+    int pos = D->pclabels[pc];
+    if (pos < 0) return *DASM_POS2PTR(D, -pos);
+    if (pos > 0) return -1;  /* Undefined. */
+  }
+  return -2;  /* Unused or out of range. */
+}
+
+#ifdef DASM_CHECKS
+/* Optional sanity checker to call between isolated encoding steps. */
+int dasm_checkstep(Dst_DECL, int secmatch)
+{
+  dasm_State *D = Dst_REF;
+  if (D->status == DASM_S_OK) {
+    int i;
+    for (i = 1; i <= 9; i++) {
+      if (D->lglabels[i] > 0) { D->status = DASM_S_UNDEF_L|i; break; }
+      D->lglabels[i] = 0;
+    }
+  }
+  if (D->status == DASM_S_OK && secmatch >= 0 &&
+      D->section != &D->sections[secmatch])
+    D->status = DASM_S_MATCH_SEC|(int)(D->section-D->sections);
+  return D->status;
+}
+#endif
+