diff --git a/src/Makefile b/src/Makefile
index 07a94251..82a57032 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -603,7 +603,6 @@ E= @echo
 default all:	$(TARGET_T)
 
 amalg:
-	@grep "^[+|]" ljamalg.c
 	$(MAKE) all "LJCORE_O=ljamalg.o"
 
 clean:
diff --git a/src/lib_jit.c b/src/lib_jit.c
index c97b0d53..acd6c293 100644
--- a/src/lib_jit.c
+++ b/src/lib_jit.c
@@ -104,8 +104,8 @@ LJLIB_CF(jit_status)
   jit_State *J = L2J(L);
   L->top = L->base;
   setboolV(L->top++, (J->flags & JIT_F_ON) ? 1 : 0);
-  flagbits_to_strings(L, J->flags, JIT_F_CPU_FIRST, JIT_F_CPUSTRING);
-  flagbits_to_strings(L, J->flags, JIT_F_OPT_FIRST, JIT_F_OPTSTRING);
+  flagbits_to_strings(L, J->flags, JIT_F_CPU, JIT_F_CPUSTRING);
+  flagbits_to_strings(L, J->flags, JIT_F_OPT, JIT_F_OPTSTRING);
   return (int)(L->top - L->base);
 #else
   setboolV(L->top++, 0);
@@ -471,7 +471,7 @@ static int jitopt_flag(jit_State *J, const char *str)
     str += str[2] == '-' ? 3 : 2;
     set = 0;
   }
-  for (opt = JIT_F_OPT_FIRST; ; opt <<= 1) {
+  for (opt = JIT_F_OPT; ; opt <<= 1) {
     size_t len = *(const uint8_t *)lst;
     if (len == 0)
       break;
@@ -640,59 +640,41 @@ JIT_PARAMDEF(JIT_PARAMINIT)
 #undef JIT_PARAMINIT
   0
 };
-#endif
 
 #if LJ_TARGET_ARM && LJ_TARGET_LINUX
 #include <sys/utsname.h>
 #endif
 
-/* Arch-dependent CPU detection. */
-static uint32_t jit_cpudetect(lua_State *L)
+/* Arch-dependent CPU feature detection. */
+static uint32_t jit_cpudetect(void)
 {
   uint32_t flags = 0;
 #if LJ_TARGET_X86ORX64
+
   uint32_t vendor[4];
   uint32_t features[4];
   if (lj_vm_cpuid(0, vendor) && lj_vm_cpuid(1, features)) {
-#if !LJ_HASJIT
-#define JIT_F_SSE2	2
-#endif
-    flags |= ((features[3] >> 26)&1) * JIT_F_SSE2;
-#if LJ_HASJIT
     flags |= ((features[2] >> 0)&1) * JIT_F_SSE3;
     flags |= ((features[2] >> 19)&1) * JIT_F_SSE4_1;
-    if (vendor[2] == 0x6c65746e) {  /* Intel. */
-      if ((features[0] & 0x0fff0ff0) == 0x000106c0)  /* Atom. */
-	flags |= JIT_F_LEA_AGU;
-    } else if (vendor[2] == 0x444d4163) {  /* AMD. */
-      uint32_t fam = (features[0] & 0x0ff00f00);
-      if (fam >= 0x00000f00)  /* K8, K10. */
-	flags |= JIT_F_PREFER_IMUL;
-    }
     if (vendor[0] >= 7) {
       uint32_t xfeatures[4];
       lj_vm_cpuid(7, xfeatures);
       flags |= ((xfeatures[1] >> 8)&1) * JIT_F_BMI2;
     }
-#endif
   }
-  /* Check for required instruction set support on x86 (unnecessary on x64). */
-#if LJ_TARGET_X86
-  if (!(flags & JIT_F_SSE2))
-    luaL_error(L, "CPU with SSE2 required");
-#endif
+  /* Don't bother checking for SSE2 -- the VM will crash before getting here. */
+
 #elif LJ_TARGET_ARM
-#if LJ_HASJIT
+
   int ver = LJ_ARCH_VERSION;  /* Compile-time ARM CPU detection. */
 #if LJ_TARGET_LINUX
   if (ver < 70) {  /* Runtime ARM CPU detection. */
     struct utsname ut;
     uname(&ut);
     if (strncmp(ut.machine, "armv", 4) == 0) {
-      if (ut.machine[4] >= '7')
-	ver = 70;
-      else if (ut.machine[4] == '6')
-	ver = 60;
+      if (ut.machine[4] >= '8') ver = 80;
+      else if (ut.machine[4] == '7') ver = 70;
+      else if (ut.machine[4] == '6') ver = 60;
     }
   }
 #endif
@@ -700,20 +682,22 @@ static uint32_t jit_cpudetect(lua_State *L)
 	   ver >= 61 ? JIT_F_ARMV6T2_ :
 	   ver >= 60 ? JIT_F_ARMV6_ : 0;
   flags |= LJ_ARCH_HASFPU == 0 ? 0 : ver >= 70 ? JIT_F_VFPV3 : JIT_F_VFPV2;
-#endif
+
 #elif LJ_TARGET_ARM64
+
   /* No optional CPU features to detect (for now). */
+
 #elif LJ_TARGET_PPC
-#if LJ_HASJIT
+
 #if LJ_ARCH_SQRT
   flags |= JIT_F_SQRT;
 #endif
 #if LJ_ARCH_ROUND
   flags |= JIT_F_ROUND;
 #endif
-#endif
+
 #elif LJ_TARGET_MIPS
-#if LJ_HASJIT
+
   /* Compile-time MIPS CPU detection. */
 #if LJ_ARCH_VERSION >= 20
   flags |= JIT_F_MIPSXXR2;
@@ -731,31 +715,28 @@ static uint32_t jit_cpudetect(lua_State *L)
     if (x) flags |= JIT_F_MIPSXXR2;  /* Either 0x80000000 (R2) or 0 (R1). */
   }
 #endif
-#endif
+
 #else
 #error "Missing CPU detection for this architecture"
 #endif
-  UNUSED(L);
   return flags;
 }
 
 /* Initialize JIT compiler. */
 static void jit_init(lua_State *L)
 {
-  uint32_t flags = jit_cpudetect(L);
-#if LJ_HASJIT
   jit_State *J = L2J(L);
-  J->flags = flags | JIT_F_ON | JIT_F_OPT_DEFAULT;
+  J->flags = jit_cpudetect() | JIT_F_ON | JIT_F_OPT_DEFAULT;
   memcpy(J->param, jit_param_default, sizeof(J->param));
   lj_dispatch_update(G(L));
-#else
-  UNUSED(flags);
-#endif
 }
+#endif
 
 LUALIB_API int luaopen_jit(lua_State *L)
 {
+#if LJ_HASJIT
   jit_init(L);
+#endif
   lua_pushliteral(L, LJ_OS_NAME);
   lua_pushliteral(L, LJ_ARCH_NAME);
   lua_pushinteger(L, LUAJIT_VERSION_NUM);
diff --git a/src/lj_arch.h b/src/lj_arch.h
index 027b39ce..70426838 100644
--- a/src/lj_arch.h
+++ b/src/lj_arch.h
@@ -208,13 +208,13 @@
 #define LJ_TARGET_UNIFYROT	2	/* Want only IR_BROR. */
 #define LJ_ARCH_NUMMODE		LJ_NUMMODE_DUAL
 
-#if __ARM_ARCH_8__ || __ARM_ARCH_8A__
+#if __ARM_ARCH == 8 || __ARM_ARCH_8__ || __ARM_ARCH_8A__
 #define LJ_ARCH_VERSION		80
-#elif __ARM_ARCH_7__ || __ARM_ARCH_7A__ || __ARM_ARCH_7R__ || __ARM_ARCH_7S__ || __ARM_ARCH_7VE__
+#elif __ARM_ARCH == 7 || __ARM_ARCH_7__ || __ARM_ARCH_7A__ || __ARM_ARCH_7R__ || __ARM_ARCH_7S__ || __ARM_ARCH_7VE__
 #define LJ_ARCH_VERSION		70
 #elif __ARM_ARCH_6T2__
 #define LJ_ARCH_VERSION		61
-#elif __ARM_ARCH_6__ || __ARM_ARCH_6J__ || __ARM_ARCH_6K__ || __ARM_ARCH_6Z__ || __ARM_ARCH_6ZK__
+#elif __ARM_ARCH == 6 || __ARM_ARCH_6__ || __ARM_ARCH_6J__ || __ARM_ARCH_6K__ || __ARM_ARCH_6Z__ || __ARM_ARCH_6ZK__
 #define LJ_ARCH_VERSION		60
 #else
 #define LJ_ARCH_VERSION		50
diff --git a/src/lj_asm_x86.h b/src/lj_asm_x86.h
index db3409b9..bf818f5a 100644
--- a/src/lj_asm_x86.h
+++ b/src/lj_asm_x86.h
@@ -1214,13 +1214,8 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
     emit_rmro(as, XO_MOV, dest|REX_GC64, tab, offsetof(GCtab, node));
   } else {
     emit_rmro(as, XO_ARITH(XOg_ADD), dest|REX_GC64, tab, offsetof(GCtab,node));
-    if ((as->flags & JIT_F_PREFER_IMUL)) {
-      emit_i8(as, sizeof(Node));
-      emit_rr(as, XO_IMULi8, dest, dest);
-    } else {
-      emit_shifti(as, XOg_SHL, dest, 3);
-      emit_rmrxo(as, XO_LEA, dest, dest, dest, XM_SCALE2, 0);
-    }
+    emit_shifti(as, XOg_SHL, dest, 3);
+    emit_rmrxo(as, XO_LEA, dest, dest, dest, XM_SCALE2, 0);
     if (isk) {
       emit_gri(as, XG_ARITHi(XOg_AND), dest, (int32_t)khash);
       emit_rmro(as, XO_MOV, dest, tab, offsetof(GCtab, hmask));
@@ -1279,7 +1274,7 @@ static void asm_hrefk(ASMState *as, IRIns *ir)
   lua_assert(ofs % sizeof(Node) == 0);
   if (ra_hasreg(dest)) {
     if (ofs != 0) {
-      if (dest == node && !(as->flags & JIT_F_LEA_AGU))
+      if (dest == node)
 	emit_gri(as, XG_ARITHi(XOg_ADD), dest|REX_GC64, ofs);
       else
 	emit_rmro(as, XO_LEA, dest|REX_GC64, node, ofs);
@@ -2180,8 +2175,7 @@ static void asm_add(ASMState *as, IRIns *ir)
 {
   if (irt_isnum(ir->t))
     asm_fparith(as, ir, XO_ADDSD);
-  else if ((as->flags & JIT_F_LEA_AGU) || as->flagmcp == as->mcp ||
-	   irt_is64(ir->t) || !asm_lea(as, ir))
+  else if (as->flagmcp == as->mcp || irt_is64(ir->t) || !asm_lea(as, ir))
     asm_intarith(as, ir, XOg_ADD);
 }
 
@@ -2903,7 +2897,7 @@ static void asm_tail_fixup(ASMState *as, TraceNo lnk)
   MCode *target, *q;
   int32_t spadj = as->T->spadjust;
   if (spadj == 0) {
-    p -= ((as->flags & JIT_F_LEA_AGU) ? 7 : 6) + (LJ_64 ? 1 : 0);
+    p -= LJ_64 ? 7 : 6;
   } else {
     MCode *p1;
     /* Patch stack adjustment. */
@@ -2915,20 +2909,11 @@ static void asm_tail_fixup(ASMState *as, TraceNo lnk)
       p1 = p-9;
       *(int32_t *)p1 = spadj;
     }
-    if ((as->flags & JIT_F_LEA_AGU)) {
 #if LJ_64
-      p1[-4] = 0x48;
+    p1[-3] = 0x48;
 #endif
-      p1[-3] = (MCode)XI_LEA;
-      p1[-2] = MODRM(checki8(spadj) ? XM_OFS8 : XM_OFS32, RID_ESP, RID_ESP);
-      p1[-1] = MODRM(XM_SCALE1, RID_ESP, RID_ESP);
-    } else {
-#if LJ_64
-      p1[-3] = 0x48;
-#endif
-      p1[-2] = (MCode)(checki8(spadj) ? XI_ARITHi8 : XI_ARITHi);
-      p1[-1] = MODRM(XM_REG, XOg_ADD, RID_ESP);
-    }
+    p1[-2] = (MCode)(checki8(spadj) ? XI_ARITHi8 : XI_ARITHi);
+    p1[-1] = MODRM(XM_REG, XOg_ADD, RID_ESP);
   }
   /* Patch exit branch. */
   target = lnk ? traceref(as->J, lnk)->mcode : (MCode *)lj_vm_exit_interp;
@@ -2959,7 +2944,7 @@ static void asm_tail_prep(ASMState *as)
     as->invmcp = as->mcp = p;
   } else {
     /* Leave room for ESP adjustment: add esp, imm or lea esp, [esp+imm] */
-    as->mcp = p - (((as->flags & JIT_F_LEA_AGU) ? 7 : 6)  + (LJ_64 ? 1 : 0));
+    as->mcp = p - (LJ_64 ? 7 : 6);
     as->invmcp = NULL;
   }
 }
diff --git a/src/lj_dispatch.c b/src/lj_dispatch.c
index 8553438c..39416d00 100644
--- a/src/lj_dispatch.c
+++ b/src/lj_dispatch.c
@@ -252,15 +252,8 @@ int luaJIT_setmode(lua_State *L, int idx, int mode)
     } else {
       if (!(mode & LUAJIT_MODE_ON))
 	G2J(g)->flags &= ~(uint32_t)JIT_F_ON;
-#if LJ_TARGET_X86ORX64
-      else if ((G2J(g)->flags & JIT_F_SSE2))
-	G2J(g)->flags |= (uint32_t)JIT_F_ON;
-      else
-	return 0;  /* Don't turn on JIT compiler without SSE2 support. */
-#else
       else
 	G2J(g)->flags |= (uint32_t)JIT_F_ON;
-#endif
       lj_dispatch_update(g);
     }
     break;
diff --git a/src/lj_emit_x86.h b/src/lj_emit_x86.h
index bc4391a0..b17e28a5 100644
--- a/src/lj_emit_x86.h
+++ b/src/lj_emit_x86.h
@@ -559,10 +559,7 @@ static void emit_storeofs(ASMState *as, IRIns *ir, Reg r, Reg base, int32_t ofs)
 static void emit_addptr(ASMState *as, Reg r, int32_t ofs)
 {
   if (ofs) {
-    if ((as->flags & JIT_F_LEA_AGU))
-      emit_rmro(as, XO_LEA, r|REX_GC64, r, ofs);
-    else
-      emit_gri(as, XG_ARITHi(XOg_ADD), r|REX_GC64, ofs);
+    emit_gri(as, XG_ARITHi(XOg_ADD), r|REX_GC64, ofs);
   }
 }
 
diff --git a/src/lj_errmsg.h b/src/lj_errmsg.h
index efb7c3f3..9110dc7e 100644
--- a/src/lj_errmsg.h
+++ b/src/lj_errmsg.h
@@ -101,11 +101,7 @@ ERRDEF(STRGSRV,	"invalid replacement value (a %s)")
 ERRDEF(BADMODN,	"name conflict for module " LUA_QS)
 #if LJ_HASJIT
 ERRDEF(JITPROT,	"runtime code generation failed, restricted kernel?")
-#if LJ_TARGET_X86ORX64
-ERRDEF(NOJIT,	"JIT compiler disabled, CPU does not support SSE2")
-#else
 ERRDEF(NOJIT,	"JIT compiler disabled")
-#endif
 #elif defined(LJ_ARCH_NOJIT)
 ERRDEF(NOJIT,	"no JIT compiler for this architecture (yet)")
 #else
diff --git a/src/lj_jit.h b/src/lj_jit.h
index f179f17f..a9c602f0 100644
--- a/src/lj_jit.h
+++ b/src/lj_jit.h
@@ -9,47 +9,49 @@
 #include "lj_obj.h"
 #include "lj_ir.h"
 
-/* JIT engine flags. */
+/* -- JIT engine flags ---------------------------------------------------- */
+
+/* General JIT engine flags. 4 bits. */
 #define JIT_F_ON		0x00000001
 
-/* CPU-specific JIT engine flags. */
+/* CPU-specific JIT engine flags. 12 bits. Flags and strings must match. */
+#define JIT_F_CPU		0x00000010
+
 #if LJ_TARGET_X86ORX64
-#define JIT_F_SSE2		0x00000010
-#define JIT_F_SSE3		0x00000020
-#define JIT_F_SSE4_1		0x00000040
-#define JIT_F_PREFER_IMUL	0x00000080
-#define JIT_F_LEA_AGU		0x00000100
-#define JIT_F_BMI2		0x00000200
 
-/* Names for the CPU-specific flags. Must match the order above. */
-#define JIT_F_CPU_FIRST		JIT_F_SSE2
-#define JIT_F_CPUSTRING		"\4SSE2\4SSE3\6SSE4.1\3AMD\4ATOM\4BMI2"
+#define JIT_F_SSE3		(JIT_F_CPU << 0)
+#define JIT_F_SSE4_1		(JIT_F_CPU << 1)
+#define JIT_F_BMI2		(JIT_F_CPU << 2)
+
+
+#define JIT_F_CPUSTRING		"\4SSE3\6SSE4.1\4BMI2"
+
 #elif LJ_TARGET_ARM
-#define JIT_F_ARMV6_		0x00000010
-#define JIT_F_ARMV6T2_		0x00000020
-#define JIT_F_ARMV7		0x00000040
-#define JIT_F_VFPV2		0x00000080
-#define JIT_F_VFPV3		0x00000100
 
-#define JIT_F_ARMV6		(JIT_F_ARMV6_|JIT_F_ARMV6T2_|JIT_F_ARMV7)
-#define JIT_F_ARMV6T2		(JIT_F_ARMV6T2_|JIT_F_ARMV7)
+#define JIT_F_ARMV6_		(JIT_F_CPU << 0)
+#define JIT_F_ARMV6T2_		(JIT_F_CPU << 1)
+#define JIT_F_ARMV7		(JIT_F_CPU << 2)
+#define JIT_F_ARMV8		(JIT_F_CPU << 3)
+#define JIT_F_VFPV2		(JIT_F_CPU << 4)
+#define JIT_F_VFPV3		(JIT_F_CPU << 5)
+
+#define JIT_F_ARMV6		(JIT_F_ARMV6_|JIT_F_ARMV6T2_|JIT_F_ARMV7|JIT_F_ARMV8)
+#define JIT_F_ARMV6T2		(JIT_F_ARMV6T2_|JIT_F_ARMV7|JIT_F_ARMV8)
 #define JIT_F_VFP		(JIT_F_VFPV2|JIT_F_VFPV3)
 
-/* Names for the CPU-specific flags. Must match the order above. */
-#define JIT_F_CPU_FIRST		JIT_F_ARMV6_
-#define JIT_F_CPUSTRING		"\5ARMv6\7ARMv6T2\5ARMv7\5VFPv2\5VFPv3"
+#define JIT_F_CPUSTRING		"\5ARMv6\7ARMv6T2\5ARMv7\5ARMv8\5VFPv2\5VFPv3"
+
 #elif LJ_TARGET_PPC
-#define JIT_F_SQRT		0x00000010
-#define JIT_F_ROUND		0x00000020
 
-/* Names for the CPU-specific flags. Must match the order above. */
-#define JIT_F_CPU_FIRST		JIT_F_SQRT
+#define JIT_F_SQRT		(JIT_F_CPU << 0)
+#define JIT_F_ROUND		(JIT_F_CPU << 1)
+
 #define JIT_F_CPUSTRING		"\4SQRT\5ROUND"
-#elif LJ_TARGET_MIPS
-#define JIT_F_MIPSXXR2		0x00000010
 
-/* Names for the CPU-specific flags. Must match the order above. */
-#define JIT_F_CPU_FIRST		JIT_F_MIPSXXR2
+#elif LJ_TARGET_MIPS
+
+#define JIT_F_MIPSXXR2		(JIT_F_CPU << 0)
+
 #if LJ_TARGET_MIPS32
 #if LJ_TARGET_MIPSR6
 #define JIT_F_CPUSTRING		"\010MIPS32R6"
@@ -63,27 +65,29 @@
 #define JIT_F_CPUSTRING		"\010MIPS64R2"
 #endif
 #endif
+
 #else
-#define JIT_F_CPU_FIRST		0
+
 #define JIT_F_CPUSTRING		""
+
 #endif
 
-/* Optimization flags. */
+/* Optimization flags. 12 bits. */
+#define JIT_F_OPT		0x00010000
 #define JIT_F_OPT_MASK		0x0fff0000
 
-#define JIT_F_OPT_FOLD		0x00010000
-#define JIT_F_OPT_CSE		0x00020000
-#define JIT_F_OPT_DCE		0x00040000
-#define JIT_F_OPT_FWD		0x00080000
-#define JIT_F_OPT_DSE		0x00100000
-#define JIT_F_OPT_NARROW	0x00200000
-#define JIT_F_OPT_LOOP		0x00400000
-#define JIT_F_OPT_ABC		0x00800000
-#define JIT_F_OPT_SINK		0x01000000
-#define JIT_F_OPT_FUSE		0x02000000
+#define JIT_F_OPT_FOLD		(JIT_F_OPT << 0)
+#define JIT_F_OPT_CSE		(JIT_F_OPT << 1)
+#define JIT_F_OPT_DCE		(JIT_F_OPT << 2)
+#define JIT_F_OPT_FWD		(JIT_F_OPT << 3)
+#define JIT_F_OPT_DSE		(JIT_F_OPT << 4)
+#define JIT_F_OPT_NARROW	(JIT_F_OPT << 5)
+#define JIT_F_OPT_LOOP		(JIT_F_OPT << 6)
+#define JIT_F_OPT_ABC		(JIT_F_OPT << 7)
+#define JIT_F_OPT_SINK		(JIT_F_OPT << 8)
+#define JIT_F_OPT_FUSE		(JIT_F_OPT << 9)
 
 /* Optimizations names for -O. Must match the order above. */
-#define JIT_F_OPT_FIRST		JIT_F_OPT_FOLD
 #define JIT_F_OPTSTRING	\
   "\4fold\3cse\3dce\3fwd\3dse\6narrow\4loop\3abc\4sink\4fuse"
 
@@ -95,6 +99,8 @@
   JIT_F_OPT_FWD|JIT_F_OPT_DSE|JIT_F_OPT_ABC|JIT_F_OPT_SINK|JIT_F_OPT_FUSE)
 #define JIT_F_OPT_DEFAULT	JIT_F_OPT_3
 
+/* -- JIT engine parameters ----------------------------------------------- */
+
 #if LJ_TARGET_WINDOWS || LJ_64
 /* See: http://blogs.msdn.com/oldnewthing/archive/2003/10/08/55239.aspx */
 #define JIT_P_sizemcode_DEFAULT		64
@@ -137,6 +143,8 @@ JIT_PARAMDEF(JIT_PARAMENUM)
 #define JIT_PARAMSTR(len, name, value)	#len #name
 #define JIT_P_STRING	JIT_PARAMDEF(JIT_PARAMSTR)
 
+/* -- JIT engine data structures ------------------------------------------ */
+
 /* Trace compiler state. */
 typedef enum {
   LJ_TRACE_IDLE,	/* Trace compiler idle. */
diff --git a/src/ljamalg.c b/src/ljamalg.c
index 39542981..6712d435 100644
--- a/src/ljamalg.c
+++ b/src/ljamalg.c
@@ -3,16 +3,6 @@
 ** Copyright (C) 2005-2020 Mike Pall. See Copyright Notice in luajit.h
 */
 
-/*
-+--------------------------------------------------------------------------+
-| WARNING: Compiling the amalgamation needs a lot of virtual memory        |
-| (around 300 MB with GCC 4.x)! If you don't have enough physical memory   |
-| your machine will start swapping to disk and the compile will not finish |
-| within a reasonable amount of time.                                      |
-| So either compile on a bigger machine or use the non-amalgamated build.  |
-+--------------------------------------------------------------------------+
-*/
-
 #define ljamalg_c
 #define LUA_CORE