diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c
index a0b4986d5b6c..4b9dbbab66e8 100644
--- a/gdb/amd64-tdep.c
+++ b/gdb/amd64-tdep.c
@@ -380,9 +380,8 @@ amd64_pseudo_register_read_value (gdbarch *gdbarch, frame_info_ptr next_frame,
 }
 
 static void
-amd64_pseudo_register_write (struct gdbarch *gdbarch,
-			     struct regcache *regcache,
-			     int regnum, const gdb_byte *buf)
+amd64_pseudo_register_write (gdbarch *gdbarch, frame_info_ptr next_frame,
+			     int regnum, gdb::array_view<const gdb_byte> buf)
 {
   i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch);
 
@@ -393,41 +392,18 @@ amd64_pseudo_register_write (struct gdbarch *gdbarch,
       if (gpnum >= AMD64_NUM_LOWER_BYTE_REGS)
 	{
 	  gpnum -= AMD64_NUM_LOWER_BYTE_REGS;
-	  gdb_byte raw_buf[register_size (gdbarch, gpnum)];
-
-	  /* Read ... AH, BH, CH, DH.  */
-	  regcache->raw_read (gpnum, raw_buf);
-	  /* ... Modify ... (always little endian).  */
-	  memcpy (raw_buf + 1, buf, 1);
-	  /* ... Write.  */
-	  regcache->raw_write (gpnum, raw_buf);
+	  pseudo_to_raw_part (next_frame, buf, gpnum, 1);
 	}
       else
-	{
-	  gdb_byte raw_buf[register_size (gdbarch, gpnum)];
-
-	  /* Read ...  */
-	  regcache->raw_read (gpnum, raw_buf);
-	  /* ... Modify ... (always little endian).  */
-	  memcpy (raw_buf, buf, 1);
-	  /* ... Write.  */
-	  regcache->raw_write (gpnum, raw_buf);
-	}
+	pseudo_to_raw_part (next_frame, buf, gpnum, 0);
     }
   else if (i386_dword_regnum_p (gdbarch, regnum))
     {
       int gpnum = regnum - tdep->eax_regnum;
-      gdb_byte raw_buf[register_size (gdbarch, gpnum)];
-
-      /* Read ...  */
-      regcache->raw_read (gpnum, raw_buf);
-      /* ... Modify ... (always little endian).  */
-      memcpy (raw_buf, buf, 4);
-      /* ... Write.  */
-      regcache->raw_write (gpnum, raw_buf);
+      pseudo_to_raw_part (next_frame, buf, gpnum, 0);
     }
   else
-    i386_pseudo_register_write (gdbarch, regcache, regnum, buf);
+    i386_pseudo_register_write (gdbarch, next_frame, regnum, buf);
 }
 
 /* Implement the 'ax_pseudo_register_collect' gdbarch method.  */
@@ -3205,8 +3181,7 @@ amd64_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch,
 
   set_gdbarch_pseudo_register_read_value (gdbarch,
 					  amd64_pseudo_register_read_value);
-  set_gdbarch_deprecated_pseudo_register_write (gdbarch,
-						amd64_pseudo_register_write);
+  set_gdbarch_pseudo_register_write (gdbarch, amd64_pseudo_register_write);
   set_gdbarch_ax_pseudo_register_collect (gdbarch,
 					  amd64_ax_pseudo_register_collect);
 
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index 5f12f17bc5eb..6b4e16155fee 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -3391,26 +3391,6 @@ i386_pseudo_register_type (struct gdbarch *gdbarch, int regnum)
   internal_error (_("invalid regnum"));
 }
 
-/* Map a cooked register onto a raw register or memory.  For the i386,
-   the MMX registers need to be mapped onto floating point registers.  */
-
-static int
-i386_mmx_regnum_to_fp_regnum (readable_regcache *regcache, int regnum)
-{
-  gdbarch *arch = regcache->arch ();
-  i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (arch);
-  int mmxreg, fpreg;
-  ULONGEST fstat;
-  int tos;
-
-  mmxreg = regnum - tdep->mm0_regnum;
-  regcache->raw_read (I387_FSTAT_REGNUM (tdep), &fstat);
-  tos = (fstat >> 11) & 0x7;
-  fpreg = (mmxreg + tos) % 8;
-
-  return (I387_ST0_REGNUM (tdep) + fpreg);
-}
-
 /* Map a cooked register onto a raw register or memory.  For the i386,
    the MMX registers need to be mapped onto floating point registers.  */
 
@@ -3537,115 +3517,92 @@ i386_pseudo_register_read_value (gdbarch *gdbarch, frame_info_ptr next_frame,
 }
 
 void
-i386_pseudo_register_write (struct gdbarch *gdbarch, struct regcache *regcache,
-			    int regnum, const gdb_byte *buf)
+i386_pseudo_register_write (gdbarch *gdbarch, frame_info_ptr next_frame,
+			    const int pseudo_reg_num,
+			    gdb::array_view<const gdb_byte> buf)
 {
-  gdb_byte raw_buf[I386_MAX_REGISTER_SIZE];
-
-  if (i386_mmx_regnum_p (gdbarch, regnum))
+  if (i386_mmx_regnum_p (gdbarch, pseudo_reg_num))
     {
-      int fpnum = i386_mmx_regnum_to_fp_regnum (regcache, regnum);
+      int fpnum = i386_mmx_regnum_to_fp_regnum (next_frame, pseudo_reg_num);
 
-      /* Read ...  */
-      regcache->raw_read (fpnum, raw_buf);
-      /* ... Modify ... (always little endian).  */
-      memcpy (raw_buf, buf, register_size (gdbarch, regnum));
-      /* ... Write.  */
-      regcache->raw_write (fpnum, raw_buf);
+      pseudo_to_raw_part (next_frame, buf, fpnum, 0);
     }
   else
     {
       i386_gdbarch_tdep *tdep = gdbarch_tdep<i386_gdbarch_tdep> (gdbarch);
 
-      if (i386_bnd_regnum_p (gdbarch, regnum))
+      if (i386_bnd_regnum_p (gdbarch, pseudo_reg_num))
 	{
-	  ULONGEST upper, lower;
 	  int size = builtin_type (gdbarch)->builtin_data_ptr->length ();
 	  bfd_endian byte_order
 	    = gdbarch_byte_order (current_inferior ()->arch ());
 
 	  /* New values from input value.  */
-	  regnum -= tdep->bnd0_regnum;
-	  lower = extract_unsigned_integer (buf, size, byte_order);
-	  upper = extract_unsigned_integer (buf + size, size, byte_order);
+	  int reg_index = pseudo_reg_num - tdep->bnd0_regnum;
+	  int raw_regnum = I387_BND0R_REGNUM (tdep) + reg_index;
 
-	  /* Fetching register buffer.  */
-	  regcache->raw_read (I387_BND0R_REGNUM (tdep) + regnum,
-			      raw_buf);
+	  value *bndr_value = value_of_register (raw_regnum, next_frame);
+	  gdb::array_view<gdb_byte> bndr_view
+	    = bndr_value->contents_writeable ();
 
-	  upper = ~upper;
+	  /* Copy lower bytes directly.  */
+	  copy (buf.slice (0, size), bndr_view.slice (0, size));
 
-	  /* Set register bits.  */
-	  memcpy (raw_buf, &lower, 8);
-	  memcpy (raw_buf + 8, &upper, 8);
+	  /* Convert and then copy upper bytes.  */
+	  ULONGEST upper
+	    = extract_unsigned_integer (buf.slice (size, size), byte_order);
+	  upper = ~upper;
+	  store_unsigned_integer (bndr_view.slice (8, size), byte_order,
+				  upper);
 
-	  regcache->raw_write (I387_BND0R_REGNUM (tdep) + regnum, raw_buf);
+	  put_frame_register (next_frame, raw_regnum, bndr_view);
 	}
-      else if (i386_zmm_regnum_p (gdbarch, regnum))
+      else if (i386_zmm_regnum_p (gdbarch, pseudo_reg_num))
 	{
-	  regnum -= tdep->zmm0_regnum;
+	  /* Which register is it, relative to zmm0.  */
+	  int reg_index_0 = pseudo_reg_num - tdep->zmm0_regnum;
 
-	  if (regnum < num_lower_zmm_regs)
-	    {
-	      /* Write lower 128bits.  */
-	      regcache->raw_write (I387_XMM0_REGNUM (tdep) + regnum, buf);
-	      /* Write upper 128bits.  */
-	      regcache->raw_write (I387_YMM0_REGNUM (tdep) + regnum, buf + 16);
-	    }
+	  if (reg_index_0 < num_lower_zmm_regs)
+	    pseudo_to_concat_raw (next_frame, buf,
+				  I387_XMM0_REGNUM (tdep) + reg_index_0,
+				  I387_YMM0_REGNUM (tdep) + reg_index_0,
+				  tdep->zmm0h_regnum + reg_index_0);
 	  else
 	    {
-	      /* Write lower 128bits.  */
-	      regcache->raw_write (I387_XMM16_REGNUM (tdep) + regnum
-				   - num_lower_zmm_regs, buf);
-	      /* Write upper 128bits.  */
-	      regcache->raw_write (I387_YMM16H_REGNUM (tdep) + regnum
-				   - num_lower_zmm_regs, buf + 16);
+	      /* Which register is it, relative to zmm16.  */
+	      int reg_index_16 = reg_index_0 - num_lower_zmm_regs;
+
+	      pseudo_to_concat_raw (next_frame, buf,
+				    I387_XMM16_REGNUM (tdep) + reg_index_16,
+				    I387_YMM16H_REGNUM (tdep) + reg_index_16,
+				    tdep->zmm0h_regnum + +reg_index_0);
 	    }
-	  /* Write upper 256bits.  */
-	  regcache->raw_write (tdep->zmm0h_regnum + regnum, buf + 32);
 	}
-      else if (i386_ymm_regnum_p (gdbarch, regnum))
+      else if (i386_ymm_regnum_p (gdbarch, pseudo_reg_num))
 	{
-	  regnum -= tdep->ymm0_regnum;
+	  int i = pseudo_reg_num - tdep->ymm0_regnum;
 
-	  /* ... Write lower 128bits.  */
-	  regcache->raw_write (I387_XMM0_REGNUM (tdep) + regnum, buf);
-	  /* ... Write upper 128bits.  */
-	  regcache->raw_write (tdep->ymm0h_regnum + regnum, buf + 16);
+	  pseudo_to_concat_raw (next_frame, buf, I387_XMM0_REGNUM (tdep) + i,
+				tdep->ymm0h_regnum + i);
 	}
-      else if (i386_ymm_avx512_regnum_p (gdbarch, regnum))
+      else if (i386_ymm_avx512_regnum_p (gdbarch, pseudo_reg_num))
 	{
-	  regnum -= tdep->ymm16_regnum;
+	  int i = pseudo_reg_num - tdep->ymm16_regnum;
 
-	  /* ... Write lower 128bits.  */
-	  regcache->raw_write (I387_XMM16_REGNUM (tdep) + regnum, buf);
-	  /* ... Write upper 128bits.  */
-	  regcache->raw_write (tdep->ymm16h_regnum + regnum, buf + 16);
+	  pseudo_to_concat_raw (next_frame, buf, I387_XMM16_REGNUM (tdep) + i,
+				tdep->ymm16h_regnum + i);
 	}
-      else if (i386_word_regnum_p (gdbarch, regnum))
+      else if (i386_word_regnum_p (gdbarch, pseudo_reg_num))
 	{
-	  int gpnum = regnum - tdep->ax_regnum;
+	  int gpnum = pseudo_reg_num - tdep->ax_regnum;
 
-	  /* Read ...  */
-	  regcache->raw_read (gpnum, raw_buf);
-	  /* ... Modify ... (always little endian).  */
-	  memcpy (raw_buf, buf, 2);
-	  /* ... Write.  */
-	  regcache->raw_write (gpnum, raw_buf);
+	  pseudo_to_raw_part (next_frame, buf, gpnum, 0);
 	}
-      else if (i386_byte_regnum_p (gdbarch, regnum))
+      else if (i386_byte_regnum_p (gdbarch, pseudo_reg_num))
 	{
-	  int gpnum = regnum - tdep->al_regnum;
+	  int gpnum = pseudo_reg_num - tdep->al_regnum;
 
-	  /* Read ...  We read both lower and upper registers.  */
-	  regcache->raw_read (gpnum % 4, raw_buf);
-	  /* ... Modify ... (always little endian).  */
-	  if (gpnum >= 4)
-	    memcpy (raw_buf + 1, buf, 1);
-	  else
-	    memcpy (raw_buf, buf, 1);
-	  /* ... Write.  */
-	  regcache->raw_write (gpnum % 4, raw_buf);
+	  pseudo_to_raw_part (next_frame, buf, gpnum % 4, gpnum >= 4 ? 1 : 0);
 	}
       else
 	internal_error (_("invalid regnum"));
@@ -8603,8 +8560,7 @@ i386_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   /* Pseudo registers may be changed by amd64_init_abi.  */
   set_gdbarch_pseudo_register_read_value (gdbarch,
 					  i386_pseudo_register_read_value);
-  set_gdbarch_deprecated_pseudo_register_write (gdbarch,
-						i386_pseudo_register_write);
+  set_gdbarch_pseudo_register_write (gdbarch, i386_pseudo_register_write);
   set_gdbarch_ax_pseudo_register_collect (gdbarch,
 					  i386_ax_pseudo_register_collect);
 
diff --git a/gdb/i386-tdep.h b/gdb/i386-tdep.h
index 970dc8904f2a..b132da23a104 100644
--- a/gdb/i386-tdep.h
+++ b/gdb/i386-tdep.h
@@ -380,9 +380,9 @@ extern value *i386_pseudo_register_read_value (gdbarch *gdbarch,
 					       frame_info_ptr next_frame,
 					       int regnum);
 
-extern void i386_pseudo_register_write (struct gdbarch *gdbarch,
-					struct regcache *regcache,
-					int regnum, const gdb_byte *buf);
+extern void i386_pseudo_register_write (gdbarch *gdbarch,
+					frame_info_ptr next_frame, int regnum,
+					gdb::array_view<const gdb_byte> buf);
 
 extern int i386_ax_pseudo_register_collect (struct gdbarch *gdbarch,
 					    struct agent_expr *ax,
diff --git a/gdb/value.c b/gdb/value.c
index 51dca972a587..5c18bb17a781 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -4062,7 +4062,8 @@ pseudo_to_raw_part (frame_info_ptr next_frame,
 		    gdb::array_view<const gdb_byte> pseudo_buf,
 		    int raw_reg_num, int raw_offset)
 {
-  int raw_reg_size = register_size (get_frame_arch (next_frame), raw_reg_num);
+  int raw_reg_size
+    = register_size (frame_unwind_arch (next_frame), raw_reg_num);
 
   /* When overflowing a register, put_frame_register_bytes writes to the
      subsequent registers.  We don't want that behavior here, so make sure
diff --git a/gdb/value.h b/gdb/value.h
index 6a74d4e2c2ee..3b3cb9c00982 100644
--- a/gdb/value.h
+++ b/gdb/value.h
@@ -1664,7 +1664,7 @@ value *pseudo_from_raw_part (frame_info_ptr next_frame, int pseudo_reg_num,
 /* Write PSEUDO_BUF, the contents of a pseudo register, to part of raw register
    RAW_REG_NUM starting at RAW_OFFSET.  */
 
-void pseudo_to_raw_part (frame_info_ptr this_frame,
+void pseudo_to_raw_part (frame_info_ptr next_frame,
 			 gdb::array_view<const gdb_byte> pseudo_buf,
 			 int raw_reg_num, int raw_offset);
 
@@ -1680,7 +1680,7 @@ value *pseudo_from_concat_raw (frame_info_ptr next_frame, int pseudo_reg_num,
 /* Write PSEUDO_BUF, the contents of a pseudo register, to the two raw registers
    RAW_REG_1_NUM and RAW_REG_2_NUM.  */
 
-void pseudo_to_concat_raw (frame_info_ptr this_frame,
+void pseudo_to_concat_raw (frame_info_ptr next_frame,
 			   gdb::array_view<const gdb_byte> pseudo_buf,
 			   int raw_reg_1_num, int raw_reg_2_num);
 
@@ -1693,7 +1693,7 @@ value *pseudo_from_concat_raw (frame_info_ptr next_frame, int pseudo_reg_num,
 /* Write PSEUDO_BUF, the contents of a pseudo register, to the tthreewo raw
    registers RAW_REG_1_NUM, RAW_REG_2_NUM and RAW_REG_3_NUM.  */
 
-void pseudo_to_concat_raw (frame_info_ptr this_frame,
+void pseudo_to_concat_raw (frame_info_ptr next_frame,
 			   gdb::array_view<const gdb_byte> pseudo_buf,
 			   int raw_reg_1_num, int raw_reg_2_num,
 			   int raw_reg_3_num);
