> On 26.10.2022 15:42, Cui, Lili wrote:
> > Changed it like this. I referenced nopQ, but I don't understand that actually
> we don't have a 66 prefix, but set DFLAG for it.
> 
> DFLAG represents absolute operand size, i.e. not relative to default operand
> size (which would be flipped by a 0x66 prefix).
Got it, thanks.

> 
> > +      if (ins->intel_syntax)
> > +       {
> > +         ins->mnemonicendp = stpcpy (ins->obuf, "nop   ");
> > +       }
> > +      else
> > +       {
> > +         if (ins->rex & REX_W)
> > +           ins->mnemonicendp = stpcpy (ins->obuf, "nopq  ");
> 
> You also want "USED_REX (REX_W)" here (perhaps ahead of the if() to match
> the majority of other uses).
> 
Done, thanks.

> Jan
> 

gas/ChangeLog:

	* NEWS: Add support for Intel PREFETCHI instruction.
	* config/tc-i386.c (load_insn_p): Use prefetch* to fold all prefetches.
	(md_assemble): Add warning for illegal input of PREFETCHI.
	* doc/c-i386.texi: Document .prefetchi.
	* testsuite/gas/i386/i386.exp: Run PREFETCHI tests.
	* testsuite/gas/i386/x86-64-lfence-load.d: Add PREFETCHI.
	* testsuite/gas/i386/x86-64-lfence-load.s: Likewise.
	* testsuite/gas/i386/x86-64-prefetch.d: New test.
	* testsuite/gas/i386/x86-64-prefetchi-intel.d: Likewise.
	* testsuite/gas/i386/x86-64-prefetchi-inval-register.d: Likewise..
	* testsuite/gas/i386/x86-64-prefetchi-inval-register.s: Likewise.
	* testsuite/gas/i386/x86-64-prefetchi-warn.l: Likewise.
	* testsuite/gas/i386/x86-64-prefetchi-warn.s: Likewise.
	* testsuite/gas/i386/x86-64-prefetchi.d: Likewise.
	* testsuite/gas/i386/x86-64-prefetchi.s: Likewise.

opcodes/ChangeLog:

	* i386-dis.c (reg_table): Add MOD_0F18_REG_6 and MOD_0F18_REG_7
	(x86_64_table): Add X86_64_0F18_REG_6_MOD_0 and X86_64_0F18_REG_7_MOD_0.
	(mod_table): Add MOD_0F18_REG_6 and MOD_0F18_REG_7.
	(prefix_table): Add PREFIX_0F18_REG_6_MOD_0_X86_64 and
	PREFIX_0F18_REG_7_MOD_0_X86_64.
	(PREFETCHI_Fixup): New.
	* i386-gen.c (cpu_flag_init): Add CPU_PREFETCHI_FLAGS.
	(cpu_flags): Add CpuPREFETCHI.
	* i386-opc.h (CpuPREFETCHI): New.
	(i386_cpu_flags): Add cpuprefetchi.
	* i386-opc.tbl: Add Intel PREFETCHI instructions.
	* i386-init.h: Regenerated.
	* i386-tbl.h: Likewise.
---
 gas/NEWS                                      |  2 +
 gas/config/tc-i386.c                          | 14 +++-
 gas/doc/c-i386.texi                           |  3 +-
 gas/testsuite/gas/i386/i386.exp               |  4 +
 gas/testsuite/gas/i386/x86-64-lfence-load.d   |  2 +
 gas/testsuite/gas/i386/x86-64-lfence-load.s   |  2 +
 .../gas/i386/x86-64-prefetchi-intel.d         | 16 ++++
 .../i386/x86-64-prefetchi-inval-register.d    | 13 ++++
 .../i386/x86-64-prefetchi-inval-register.s    |  9 +++
 .../gas/i386/x86-64-prefetchi-warn.l          |  5 ++
 .../gas/i386/x86-64-prefetchi-warn.s          | 11 +++
 gas/testsuite/gas/i386/x86-64-prefetchi.d     | 15 ++++
 gas/testsuite/gas/i386/x86-64-prefetchi.s     | 14 ++++
 opcodes/i386-dis.c                            | 78 ++++++++++++++++++-
 opcodes/i386-gen.c                            |  3 +
 opcodes/i386-opc.h                            |  3 +
 opcodes/i386-opc.tbl                          |  7 ++
 17 files changed, 194 insertions(+), 7 deletions(-)
 create mode 100644 gas/testsuite/gas/i386/x86-64-prefetchi-intel.d
 create mode 100644 gas/testsuite/gas/i386/x86-64-prefetchi-inval-register.d
 create mode 100644 gas/testsuite/gas/i386/x86-64-prefetchi-inval-register.s
 create mode 100644 gas/testsuite/gas/i386/x86-64-prefetchi-warn.l
 create mode 100644 gas/testsuite/gas/i386/x86-64-prefetchi-warn.s
 create mode 100644 gas/testsuite/gas/i386/x86-64-prefetchi.d
 create mode 100644 gas/testsuite/gas/i386/x86-64-prefetchi.s

diff --git a/gas/NEWS b/gas/NEWS
index 961449545d..5eb479f5a1 100644
--- a/gas/NEWS
+++ b/gas/NEWS
@@ -1,5 +1,7 @@
 -*- text -*-
 
+* Add support for Intel PREFETCHI instructions.
+
 * Add support for Intel AMX-FP16 instructions.
 
 * Add support for Intel MSRLIST instructions.
diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index c1623f216e..d0bbf100e6 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -1102,6 +1102,7 @@ static const arch_entry cpu_arch[] =
   SUBARCH (rao_int, RAO_INT, RAO_INT, false),
   SUBARCH (wrmsrns, WRMSRNS, WRMSRNS, false),
   SUBARCH (msrlist, MSRLIST, MSRLIST, false),
+  SUBARCH (prefetchi, PREFETCHI, PREFETCHI, false),
 };
 
 #undef SUBARCH
@@ -4520,9 +4521,8 @@ load_insn_p (void)
 
   if (!any_vex_p)
     {
-      /* Anysize insns: lea, invlpg, clflush, prefetchnta, prefetcht0,
-	 prefetcht1, prefetcht2, prefetchtw, bndmk, bndcl, bndcu, bndcn,
-	 bndstx, bndldx, prefetchwt1, clflushopt, clwb, cldemote.  */
+      /* Anysize insns: lea, invlpg, clflush, prefetch*, bndmk, bndcl, bndcu,
+	 bndcn, bndstx, bndldx, clflushopt, clwb, cldemote.  */
       if (i.tm.opcode_modifier.anysize)
 	return 0;
 
@@ -5057,9 +5057,15 @@ md_assemble (char *line)
   if (!process_suffix ())
     return;
 
-  /* Update operand types and check extended states.  */
+  /* 1. Update operand types and check extended states. 
+     2. Check IP-relative addressing for prefetchi.  */
   for (j = 0; j < i.operands; j++)
     {
+      /* Check if IP-relative addressing requirements can be satisfied.  */
+      if (i.tm.cpu_flags.bitfield.cpuprefetchi
+	  && !(i.base_reg && i.base_reg->reg_num == RegIP))
+	as_warn (_("only support RIP-relative address"));
+
       i.types[j] = operand_type_and (i.types[j], i.tm.operand_types[j]);
       switch (i.tm.operand_types[j].bitfield.class)
 	{
diff --git a/gas/doc/c-i386.texi b/gas/doc/c-i386.texi
index b33f17c698..fae902c034 100644
--- a/gas/doc/c-i386.texi
+++ b/gas/doc/c-i386.texi
@@ -201,6 +201,7 @@ accept various extension mnemonics.  For example,
 @code{rao_int},
 @code{wrmsrns},
 @code{msrlist},
+@code{prefetchi},
 @code{amx_int8},
 @code{amx_bf16},
 @code{amx_fp16},
@@ -1496,7 +1497,7 @@ supported on the CPU specified.  The choices for @var{cpu_type} are:
 @item @samp{.clwb} @tab @samp{.rdpid} @tab @samp{.ptwrite} @tab @samp{.ibt}
 @item @samp{.avx_ifma} @tab @samp{.avx_vnni_int8} @tab @samp{.avx_ne_convert}
 @item @samp{.cmpccxadd} @tab @samp{.rao_int} @tab @samp{.wrmsrns}
-@item @samp{.msrlist}
+@item @samp{.msrlist} @tab @samp{.prefetchi}
 @item @samp{.wbnoinvd} @tab @samp{.pconfig} @tab @samp{.waitpkg} @tab @samp{.cldemote}
 @item @samp{.shstk} @tab @samp{.gfni} @tab @samp{.vaes} @tab @samp{.vpclmulqdq}
 @item @samp{.movdiri} @tab @samp{.movdir64b} @tab @samp{.enqcmd} @tab @samp{.tsxldtrk}
diff --git a/gas/testsuite/gas/i386/i386.exp b/gas/testsuite/gas/i386/i386.exp
index 9f5fa7f612..2081339dc9 100644
--- a/gas/testsuite/gas/i386/i386.exp
+++ b/gas/testsuite/gas/i386/i386.exp
@@ -1209,6 +1209,10 @@ if [gas_64_check] then {
     run_dump_test "x86-64-tdx"
     run_dump_test "x86-64-tsxldtrk"
     run_dump_test "x86-64-hreset"
+    run_dump_test "x86-64-prefetchi"
+    run_dump_test "x86-64-prefetchi-intel"
+    run_dump_test "x86-64-prefetchi-inval-register"
+    run_list_test "x86-64-prefetchi-warn"
     run_dump_test "x86-64-vp2intersect"
     run_dump_test "x86-64-vp2intersect-intel"
     run_list_test "x86-64-vp2intersect-inval-bcast"
diff --git a/gas/testsuite/gas/i386/x86-64-lfence-load.d b/gas/testsuite/gas/i386/x86-64-lfence-load.d
index 2af86fc93f..17c3b9f286 100644
--- a/gas/testsuite/gas/i386/x86-64-lfence-load.d
+++ b/gas/testsuite/gas/i386/x86-64-lfence-load.d
@@ -33,6 +33,8 @@ Disassembly of section .text:
  +[a-f0-9]+:	0f 18 55 00          	prefetcht1 0x0\(%rbp\)
  +[a-f0-9]+:	0f 18 5d 00          	prefetcht2 0x0\(%rbp\)
  +[a-f0-9]+:	0f 0d 4d 00          	prefetchw 0x0\(%rbp\)
+ +[a-f0-9]+:	0f 18 3d 78 56 34 12 	prefetchit0 0x12345678\(%rip\)        # [0-9a-f]+ <_start\+0x[0-9a-f]+>
+ +[a-f0-9]+:	0f 18 35 78 56 34 12 	prefetchit1 0x12345678\(%rip\)        # [0-9a-f]+ <_start\+0x[0-9a-f]+>
  +[a-f0-9]+:	0f a1                	pop    %fs
  +[a-f0-9]+:	0f ae e8             	lfence
  +[a-f0-9]+:	9d                   	popf
diff --git a/gas/testsuite/gas/i386/x86-64-lfence-load.s b/gas/testsuite/gas/i386/x86-64-lfence-load.s
index 2a3ac6b7d2..c478082416 100644
--- a/gas/testsuite/gas/i386/x86-64-lfence-load.s
+++ b/gas/testsuite/gas/i386/x86-64-lfence-load.s
@@ -20,6 +20,8 @@ _start:
 	prefetcht1 (%rbp)
 	prefetcht2 (%rbp)
 	prefetchw (%rbp)
+	prefetchit0 0x12345678(%rip)
+	prefetchit1 0x12345678(%rip)
 	pop %fs
 	popf
 	xlatb (%rbx)
diff --git a/gas/testsuite/gas/i386/x86-64-prefetchi-intel.d b/gas/testsuite/gas/i386/x86-64-prefetchi-intel.d
new file mode 100644
index 0000000000..7f72f0a1eb
--- /dev/null
+++ b/gas/testsuite/gas/i386/x86-64-prefetchi-intel.d
@@ -0,0 +1,16 @@
+#as:
+#objdump: -dwMintel
+#name: x86-64 PREFETCHI insns (Intel disassembly)
+#source: x86-64-prefetchi.s
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+0+ <_start>:
+[ 	]*[a-f0-9]+:	0f 18 3d 78 56 34 12 	prefetchit0 BYTE PTR \[rip\+0x12345678\]        # [0-9a-f]+ <_start\+0x[0-9a-f]+>
+[ 	]*[a-f0-9]+:	0f 18 35 78 56 34 12 	prefetchit1 BYTE PTR \[rip\+0x12345678\]        # [0-9a-f]+ <_start\+0x[0-9a-f]+>
+[ 	]*[a-f0-9]+:	0f 18 3d 78 56 34 12 	prefetchit0 BYTE PTR \[rip\+0x12345678\]        # [0-9a-f]+ <_start\+0x[0-9a-f]+>
+[ 	]*[a-f0-9]+:	0f 18 35 78 56 34 12 	prefetchit1 BYTE PTR \[rip\+0x12345678\]        # [0-9a-f]+ <_start\+0x[0-9a-f]+>
+#pass
diff --git a/gas/testsuite/gas/i386/x86-64-prefetchi-inval-register.d b/gas/testsuite/gas/i386/x86-64-prefetchi-inval-register.d
new file mode 100644
index 0000000000..b29b1ae237
--- /dev/null
+++ b/gas/testsuite/gas/i386/x86-64-prefetchi-inval-register.d
@@ -0,0 +1,13 @@
+#as:
+#objdump: -dw
+#name: x86-64 PREFETCHI INVAL REGISTER insns
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+0+ <\.text>:
+[ 	]*[a-f0-9]+:[ 	]0f 18 39[ 	]*nopl   \(%rcx\)
+[ 	]*[a-f0-9]+:[ 	]0f 18 31[ 	]*nopl   \(%rcx\)
+#pass
diff --git a/gas/testsuite/gas/i386/x86-64-prefetchi-inval-register.s b/gas/testsuite/gas/i386/x86-64-prefetchi-inval-register.s
new file mode 100644
index 0000000000..550449a0c9
--- /dev/null
+++ b/gas/testsuite/gas/i386/x86-64-prefetchi-inval-register.s
@@ -0,0 +1,9 @@
+.text
+        #prefetchit0 (%rcx) PREFETCHIT0/1 apply without RIP-relative addressing, should stay NOPs.
+        .byte 0x0f
+        .byte 0x18
+        .byte 0x39
+        #prefetchit1 (%rcx) PREFETCHIT1/1 apply without RIP-relative addressing, should stay NOPs.
+        .byte 0x0f
+        .byte 0x18
+        .byte 0x31
diff --git a/gas/testsuite/gas/i386/x86-64-prefetchi-warn.l b/gas/testsuite/gas/i386/x86-64-prefetchi-warn.l
new file mode 100644
index 0000000000..4e15389463
--- /dev/null
+++ b/gas/testsuite/gas/i386/x86-64-prefetchi-warn.l
@@ -0,0 +1,5 @@
+.*: Assembler messages:
+.*:[0-9]*: Warning: only support RIP-relative address
+.*:[0-9]*: Warning: only support RIP-relative address
+.*:[0-9]*: Warning: only support RIP-relative address
+.*:[0-9]*: Warning: only support RIP-relative address
diff --git a/gas/testsuite/gas/i386/x86-64-prefetchi-warn.s b/gas/testsuite/gas/i386/x86-64-prefetchi-warn.s
new file mode 100644
index 0000000000..330ff31c75
--- /dev/null
+++ b/gas/testsuite/gas/i386/x86-64-prefetchi-warn.s
@@ -0,0 +1,11 @@
+# Check error for ICACHE-PREFETCH 64-bit instruction
+
+	.allow_index_reg
+	.text
+_start:
+	prefetchit0     0x12345678(%rax)
+	prefetchit1     0x12345678(%rax)
+
+	.intel_syntax noprefix
+	prefetchit0     BYTE PTR [rax+0x12345678]
+	prefetchit1     BYTE PTR [rax+0x12345678]
diff --git a/gas/testsuite/gas/i386/x86-64-prefetchi.d b/gas/testsuite/gas/i386/x86-64-prefetchi.d
new file mode 100644
index 0000000000..c8ab92d147
--- /dev/null
+++ b/gas/testsuite/gas/i386/x86-64-prefetchi.d
@@ -0,0 +1,15 @@
+#as:
+#objdump: -dw
+#name: x86-64 PREFETCHI insns
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+0+ <_start>:
+[ 	]*[a-f0-9]+:	0f 18 3d 78 56 34 12 	prefetchit0 0x12345678\(%rip\)        # [0-9a-f]+ <_start\+0x[0-9a-f]+>
+[ 	]*[a-f0-9]+:	0f 18 35 78 56 34 12 	prefetchit1 0x12345678\(%rip\)        # [0-9a-f]+ <_start\+0x[0-9a-f]+>
+[ 	]*[a-f0-9]+:	0f 18 3d 78 56 34 12 	prefetchit0 0x12345678\(%rip\)        # [0-9a-f]+ <_start\+0x[0-9a-f]+>
+[ 	]*[a-f0-9]+:	0f 18 35 78 56 34 12 	prefetchit1 0x12345678\(%rip\)        # [0-9a-f]+ <_start\+0x[0-9a-f]+>
+#pass
diff --git a/gas/testsuite/gas/i386/x86-64-prefetchi.s b/gas/testsuite/gas/i386/x86-64-prefetchi.s
new file mode 100644
index 0000000000..cc7c61e9a9
--- /dev/null
+++ b/gas/testsuite/gas/i386/x86-64-prefetchi.s
@@ -0,0 +1,14 @@
+# Check 64bit PREFETCHI instructions
+
+	.allow_index_reg
+	.text
+_start:
+
+        prefetchit0     0x12345678(%rip)
+        prefetchit1     0x12345678(%rip)
+
+        .intel_syntax noprefix
+
+        prefetchit0     BYTE PTR [rip+0x12345678]
+        prefetchit1     BYTE PTR [rip+0x12345678]
+
diff --git a/opcodes/i386-dis.c b/opcodes/i386-dis.c
index 27ae8eaf46..9ef3d7a6ae 100644
--- a/opcodes/i386-dis.c
+++ b/opcodes/i386-dis.c
@@ -114,6 +114,7 @@ static void FXSAVE_Fixup (instr_info *, int, int);
 
 static void MOVSXD_Fixup (instr_info *, int, int);
 static void DistinctDest_Fixup (instr_info *, int, int);
+static void PREFETCHI_Fixup (instr_info *, int, int);
 
 /* This character is used to encode style information within the output
    buffers.  See oappend_insert_style for more details.  */
@@ -841,6 +842,8 @@ enum
   MOD_0F18_REG_1,
   MOD_0F18_REG_2,
   MOD_0F18_REG_3,
+  MOD_0F18_REG_6,
+  MOD_0F18_REG_7,
   MOD_0F1A_PREFIX_0,
   MOD_0F1B_PREFIX_0,
   MOD_0F1B_PREFIX_1,
@@ -1006,6 +1009,8 @@ enum
   PREFIX_0F11,
   PREFIX_0F12,
   PREFIX_0F16,
+  PREFIX_0F18_REG_6_MOD_0_X86_64,
+  PREFIX_0F18_REG_7_MOD_0_X86_64,
   PREFIX_0F1A,
   PREFIX_0F1B,
   PREFIX_0F1C,
@@ -1280,6 +1285,8 @@ enum
   X86_64_0F01_REG_7_MOD_3_RM_6_PREFIX_1,
   X86_64_0F01_REG_7_MOD_3_RM_6_PREFIX_3,
   X86_64_0F01_REG_7_MOD_3_RM_7_PREFIX_1,
+  X86_64_0F18_REG_6_MOD_0,
+  X86_64_0F18_REG_7_MOD_0,
   X86_64_0F24,
   X86_64_0F26,
   X86_64_0FC7_REG_6_MOD_3_PREFIX_1,
@@ -2751,8 +2758,8 @@ static const struct dis386 reg_table[][8] = {
     { MOD_TABLE (MOD_0F18_REG_3) },
     { "nopQ",		{ Ev }, 0 },
     { "nopQ",		{ Ev }, 0 },
-    { "nopQ",		{ Ev }, 0 },
-    { "nopQ",		{ Ev }, 0 },
+    { MOD_TABLE (MOD_0F18_REG_6) },
+    { MOD_TABLE (MOD_0F18_REG_7) },
   },
   /* REG_0F1C_P_0_MOD_0 */
   {
@@ -3118,6 +3125,22 @@ static const struct dis386 prefix_table[][4] = {
     { MOD_TABLE (MOD_0F16_PREFIX_2) },
   },
 
+  /* PREFIX_0F18_REG_6_MOD_0_X86_64 */
+  {
+    { "prefetchit1",	{ { PREFETCHI_Fixup, b_mode } }, 0 },
+    { "nopQ",		{ Ev }, 0 },
+    { "nopQ",		{ Ev }, 0 },
+    { "nopQ",		{ Ev }, 0 },
+  },
+
+  /* PREFIX_0F18_REG_7_MOD_0_X86_64 */
+  {
+    { "prefetchit0",	{ { PREFETCHI_Fixup, b_mode } }, 0 },
+    { "nopQ",		{ Ev }, 0 },
+    { "nopQ",		{ Ev }, 0 },
+    { "nopQ",		{ Ev }, 0 },
+  },
+
   /* PREFIX_0F1A */
   {
     { MOD_TABLE (MOD_0F1A_PREFIX_0) },
@@ -4394,6 +4417,18 @@ static const struct dis386 x86_64_table[][2] = {
     { "psmash",	{ Skip_MODRM }, 0 },
   },
 
+  /* X86_64_0F18_REG_6_MOD_0 */
+  {
+    { "nopQ",		{ Ev }, 0 },
+    { PREFIX_TABLE (PREFIX_0F18_REG_6_MOD_0_X86_64) },
+  },
+
+  /* X86_64_0F18_REG_7_MOD_0 */
+  {
+    { "nopQ",		{ Ev }, 0 },
+    { PREFIX_TABLE (PREFIX_0F18_REG_7_MOD_0_X86_64) },
+  },
+
   {
     /* X86_64_0F24 */
     { "movZ",		{ Em, Td }, 0 },
@@ -8193,6 +8228,16 @@ static const struct dis386 mod_table[][2] = {
     { "prefetcht2",	{ Mb }, 0 },
     { "nopQ",		{ Ev }, 0 },
   },
+  {
+    /* MOD_0F18_REG_6 */
+    { X86_64_TABLE (X86_64_0F18_REG_6_MOD_0) },
+    { "nopQ",		{ Ev }, 0 },
+  },
+  {
+    /* MOD_0F18_REG_7 */
+    { X86_64_TABLE (X86_64_0F18_REG_7_MOD_0) },
+    { "nopQ",		{ Ev }, 0 },
+  },
   {
     /* MOD_0F1A_PREFIX_0 */
     { "bndldx",		{ Gbnd, Mv_bnd }, 0 },
@@ -13940,3 +13985,32 @@ OP_Rounding (instr_info *ins, int bytemode, int sizeflag ATTRIBUTE_UNUSED)
     }
   oappend (ins, "sae}");
 }
+
+static void
+PREFETCHI_Fixup (instr_info *ins, int bytemode, int sizeflag)
+{
+  if (ins->modrm.mod != 0 || ins->modrm.rm != 5)
+    {
+      if (ins->intel_syntax)
+	{
+	  ins->mnemonicendp = stpcpy (ins->obuf, "nop   ");
+	}
+      else
+	{
+	  USED_REX (REX_W);
+	  if (ins->rex & REX_W)
+	    ins->mnemonicendp = stpcpy (ins->obuf, "nopq  ");
+	  else
+	    {
+	      if (sizeflag & DFLAG)
+		ins->mnemonicendp = stpcpy (ins->obuf, "nopl  ");
+	      else
+		ins->mnemonicendp = stpcpy (ins->obuf, "nopw  ");
+	      ins->used_prefixes |= (ins->prefixes & PREFIX_DATA);
+	    }
+	}
+      bytemode = v_mode;
+    }
+
+  OP_M (ins, bytemode, sizeflag);
+}
diff --git a/opcodes/i386-gen.c b/opcodes/i386-gen.c
index 237f147ad4..33339ba840 100644
--- a/opcodes/i386-gen.c
+++ b/opcodes/i386-gen.c
@@ -259,6 +259,8 @@ static initializer cpu_flag_init[] =
     "CpuWRMSRNS" },
   { "CPU_MSRLIST_FLAGS",
     "CpuMSRLIST" },
+  { "CPU_PREFETCHI_FLAGS",
+    "CpuPREFETCHI"},
   { "CPU_IAMCU_FLAGS",
     "Cpu186|Cpu286|Cpu386|Cpu486|Cpu586|CpuIAMCU" },
   { "CPU_ADX_FLAGS",
@@ -677,6 +679,7 @@ static bitfield cpu_flags[] =
   BITFIELD (CpuRAO_INT),
   BITFIELD (CpuWRMSRNS),
   BITFIELD (CpuMSRLIST),
+  BITFIELD (CpuPREFETCHI),
   BITFIELD (CpuMWAITX),
   BITFIELD (CpuCLZERO),
   BITFIELD (CpuOSPKE),
diff --git a/opcodes/i386-opc.h b/opcodes/i386-opc.h
index 645abe7f34..1ed319c20b 100644
--- a/opcodes/i386-opc.h
+++ b/opcodes/i386-opc.h
@@ -223,6 +223,8 @@ enum
   CpuWRMSRNS,
   /* Intel MSRLIST Instructions support required.  */
   CpuMSRLIST,
+  /* PREFETCHI instruction required */
+  CpuPREFETCHI,
   /* mwaitx instruction required */
   CpuMWAITX,
   /* Clzero instruction required */
@@ -411,6 +413,7 @@ typedef union i386_cpu_flags
       unsigned int cpurao_int:1;
       unsigned int cpuwrmsrns:1;
       unsigned int cpumsrlist:1;
+      unsigned int cpuprefetchi:1;
       unsigned int cpumwaitx:1;
       unsigned int cpuclzero:1;
       unsigned int cpuospke:1;
diff --git a/opcodes/i386-opc.tbl b/opcodes/i386-opc.tbl
index bb5dc6799d..d63aa1dfb2 100644
--- a/opcodes/i386-opc.tbl
+++ b/opcodes/i386-opc.tbl
@@ -3323,3 +3323,10 @@ rdmsrlist, 0xf20f01c6, None, CpuMSRLIST|Cpu64, No_bSuf|No_wSuf|No_lSuf|No_sSuf|N
 wrmsrlist, 0xf30f01c6, None, CpuMSRLIST|Cpu64, No_bSuf|No_wSuf|No_lSuf|No_sSuf|No_qSuf|No_ldSuf, {}
 
 // MSRLIST instructions end.
+
+// PREFETCHI instructions.
+
+prefetchit0, 0xf18, 0x7, CpuPREFETCHI|Cpu64, Modrm|Anysize|IgnoreSize|No_bSuf|No_wSuf|No_lSuf|No_sSuf|No_qSuf|No_ldSuf, { BaseIndex }
+prefetchit1, 0xf18, 0x6, CpuPREFETCHI|Cpu64, Modrm|Anysize|IgnoreSize|No_bSuf|No_wSuf|No_lSuf|No_sSuf|No_qSuf|No_ldSuf, { BaseIndex }
+
+// PREFETCHI instructions end.
-- 
2.17.1

Regards,
Lili.