MIPS: Remove remnants of 48-bit microMIPS instruction support

The POOL48A major opcode was defined in early revisions of the 64-bit
microMIPS ISA, has never been implemented, and was removed before the
64-bit microMIPS ISA specification[1] has been finalized.

This complements commit a6c7053929dd ("MIPS/opcodes: Remove microMIPS
48-bit LI instruction").

References:

[1] "MIPS Architecture for Programmers, Volume II-B: The microMIPS64
    Instruction Set", MIPS Technologies, Inc., Document Number: MD00594,
    Revision 3.06, October 17, 2012, Table 6.2 "microMIPS64 Encoding of
    Major Opcode Field", p. 578

	gas/
	* config/tc-mips.c (micromips_insn_length): Remove the mention
	of 48-bit microMIPS instructions.

	gdb/
	* mips-tdep.c (mips_insn_size): Remove 48-bit microMIPS
	instruction support.
	(micromips_next_pc): Likewise.
	(micromips_scan_prologue): Likewise.
	(micromips_deal_with_atomic_sequence): Likewise.
	(micromips_stack_frame_destroyed_p): Likewise.
	(mips_breakpoint_from_pc): Likewise.

	opcodes/
	* mips-dis.c (print_insn_micromips): Remove 48-bit microMIPS
	instruction support.

2 files changed, 14 insertions, 33 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index cfe889d..e534dcc 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,15 @@
 2016-01-18  Maciej W. Rozycki  <macro@imgtec.com>
 
+	* mips-tdep.c (mips_insn_size): Remove 48-bit microMIPS
+	instruction support.
+	(micromips_next_pc): Likewise.
+	(micromips_scan_prologue): Likewise.
+	(micromips_deal_with_atomic_sequence): Likewise.
+	(micromips_stack_frame_destroyed_p): Likewise.
+	(mips_breakpoint_from_pc): Likewise.
+
+2016-01-18  Maciej W. Rozycki  <macro@imgtec.com>
+
 	* mips-tdep.c (micromips_insn_at_pc_has_delay_slot): Pass
 	unshifted 16-bit microMIPS instruction word to `mips_insn_size'.
 
diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index f787a6d..63c1560f 100644
--- a/gdb/mips-tdep.c
+++ b/gdb/mips-tdep.c
@@ -1518,10 +1518,8 @@ mips_insn_size (enum mips_isa isa, ULONGEST insn)
   switch (isa)
     {
     case ISA_MICROMIPS:
-      if (micromips_op (insn) == 0x1f)
-        return 3 * MIPS_INSN16_SIZE;
-      else if (((micromips_op (insn) & 0x4) == 0x4)
-	       || ((micromips_op (insn) & 0x7) == 0x0))
+      if ((micromips_op (insn) & 0x4) == 0x4
+	  || (micromips_op (insn) & 0x7) == 0x0)
         return 2 * MIPS_INSN16_SIZE;
       else
         return MIPS_INSN16_SIZE;
@@ -1881,12 +1879,6 @@ micromips_next_pc (struct frame_info *frame, CORE_ADDR pc)
   pc += MIPS_INSN16_SIZE;
   switch (mips_insn_size (ISA_MICROMIPS, insn))
     {
-    /* 48-bit instructions.  */
-    case 3 * MIPS_INSN16_SIZE: /* POOL48A: bits 011111 */
-      /* No branch or jump instructions in this category.  */
-      pc += 2 * MIPS_INSN16_SIZE;
-      break;
-
     /* 32-bit instructions.  */
     case 2 * MIPS_INSN16_SIZE:
       insn <<= 16;
@@ -2993,13 +2985,6 @@ micromips_scan_prologue (struct gdbarch *gdbarch,
       loc += MIPS_INSN16_SIZE;
       switch (mips_insn_size (ISA_MICROMIPS, insn))
 	{
-	/* 48-bit instructions.  */
-	case 3 * MIPS_INSN16_SIZE:
-	  /* No prologue instructions in this category.  */
-	  this_non_prologue_insn = 1;
-	  loc += 2 * MIPS_INSN16_SIZE;
-	  break;
-
 	/* 32-bit instructions.  */
 	case 2 * MIPS_INSN16_SIZE:
 	  insn <<= 16;
@@ -4041,11 +4026,6 @@ micromips_deal_with_atomic_sequence (struct gdbarch *gdbarch,
          its destination address.  */
       switch (mips_insn_size (ISA_MICROMIPS, insn))
 	{
-	/* 48-bit instructions.  */
-	case 3 * MIPS_INSN16_SIZE: /* POOL48A: bits 011111 */
-	  loc += 2 * MIPS_INSN16_SIZE;
-	  break;
-
 	/* 32-bit instructions.  */
 	case 2 * MIPS_INSN16_SIZE:
 	  switch (micromips_op (insn))
@@ -6769,11 +6749,6 @@ micromips_stack_frame_destroyed_p (struct gdbarch *gdbarch, CORE_ADDR pc)
       loc += MIPS_INSN16_SIZE;
       switch (mips_insn_size (ISA_MICROMIPS, insn))
 	{
-	/* 48-bit instructions.  */
-	case 3 * MIPS_INSN16_SIZE:
-	  /* No epilogue instructions in this category.  */
-	  return 0;
-
 	/* 32-bit instructions.  */
 	case 2 * MIPS_INSN16_SIZE:
 	  insn <<= 16;
@@ -7122,9 +7097,7 @@ mips_breakpoint_from_pc (struct gdbarch *gdbarch,
 	  int size;
 
 	  insn = mips_fetch_instruction (gdbarch, ISA_MICROMIPS, pc, &err);
-	  size = (err != 0
-		  ? 2 : (mips_insn_size (ISA_MICROMIPS, insn) == 2
-			 ? 2 : 4));
+	  size = err ? 2 : mips_insn_size (ISA_MICROMIPS, insn);
 	  *pcptr = unmake_compact_addr (pc);
 	  *lenptr = size;
 	  return (size == 2) ? micromips16_big_breakpoint
@@ -7174,9 +7147,7 @@ mips_breakpoint_from_pc (struct gdbarch *gdbarch,
 	  int size;
 
 	  insn = mips_fetch_instruction (gdbarch, ISA_MICROMIPS, pc, &err);
-	  size = (err != 0
-		  ? 2 : (mips_insn_size (ISA_MICROMIPS, insn) == 2
-			 ? 2 : 4));
+	  size = err ? 2 : mips_insn_size (ISA_MICROMIPS, insn);
 	  *pcptr = unmake_compact_addr (pc);
 	  *lenptr = size;
 	  return (size == 2) ? micromips16_little_breakpoint