* mips-tdep.c (extended_offset): Correct calculation.

	(unpack_mips16): Correct bitfield positions used for extraction
	of the immediate argument; fix sign-extension of same.
	(extended_mips16_next_pc): Correct B instruction's offset
	calculation.  Correct register decoding of the BEQZ and BNEZ
	as well as jump-register instructions.  Handle compact jumps.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5b1de6407b924bbf7a569b9c38aac1eac4708900..2fb4758e56335ec50416b09f1a77ae97ff7eecf7 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,12 @@
+2011-12-08  Maciej W. Rozycki  <macro@codesourcery.com>
+
+       * mips-tdep.c (extended_offset): Correct calculation.
+       (unpack_mips16): Correct bitfield positions used for extraction
+       of the immediate argument; fix sign-extension of same.
+       (extended_mips16_next_pc): Correct B instruction's offset
+       calculation.  Correct register decoding of the BEQZ and BNEZ
+       as well as jump-register instructions.  Handle compact jumps.
+
 2011-12-08  Tom Tromey  <tromey@redhat.com>
 
        * objfiles.h (struct objfile): Remove obsolete comment.

diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index 64b7629b12bc264221452cbc9cbfc5c51a822211..0f9a4abe0acc3da59bfd4a9a14ec6e1a6a5acdb0 100644 (file)
--- a/gdb/mips-tdep.c
+++ b/gdb/mips-tdep.c
@@ -1319,9 +1319,9 @@ extended_offset (unsigned int extension)
 {
   CORE_ADDR value;
 
-  value = (extension >> 21) & 0x3f;    /* Extract 15:11.  */
+  value = (extension >> 16) & 0x1f;    /* Extract 15:11.  */
   value = value << 6;
-  value |= (extension >> 16) & 0x1f;   /* Extract 10:5.  */
+  value |= (extension >> 21) & 0x3f;   /* Extract 10:5.  */
   value = value << 5;
   value |= extension & 0x1f;           /* Extract 4:0.  */
 
@@ -1361,14 +1361,13 @@ unpack_mips16 (struct gdbarch *gdbarch, CORE_ADDR pc,
        CORE_ADDR value;
        if (extension)
          {
-           value = extended_offset (extension);
-           value = value << 11;        /* rom for the original value */
-           value |= inst & 0x7ff;      /* eleven bits from instruction */
+           value = extended_offset ((extension << 16) | inst);
+           value = (value ^ 0x8000) - 0x8000;          /* Sign-extend.  */
          }
        else
          {
            value = inst & 0x7ff;
-           /* FIXME : Consider sign extension.  */
+           value = (value ^ 0x400) - 0x400;            /* Sign-extend.  */
          }
        offset = value;
        regx = -1;
@@ -1383,28 +1382,16 @@ unpack_mips16 (struct gdbarch *gdbarch, CORE_ADDR pc,
        CORE_ADDR value;
        if (extension)
          {
-           value = extended_offset (extension);
-           value = value << 8;         /* from the original instruction */
-           value |= inst & 0xff;       /* eleven bits from instruction */
-           regx = (extension >> 8) & 0x07;     /* or i8 funct */
-           if (value & 0x4000)         /* Test the sign bit, bit 26.  */
-             {
-               value &= ~0x3fff;       /* Remove the sign bit.  */
-               value = -value;
-             }
+           value = extended_offset ((extension << 16) | inst);
+           value = (value ^ 0x8000) - 0x8000;          /* Sign-extend.  */
          }
        else
          {
-           value = inst & 0xff;        /* 8 bits */
-           regx = (inst >> 8) & 0x07;  /* or i8 funct */
-           /* FIXME: Do sign extension, this format needs it.  */
-           if (value & 0x80)   /* THIS CONFUSES ME.  */
-             {
-               value &= 0xef;  /* Remove the sign bit.  */
-               value = -value;
-             }
+           value = inst & 0xff;                        /* 8 bits */
+           value = (value ^ 0x80) - 0x80;              /* Sign-extend.  */
          }
        offset = value;
+       regx = (inst >> 8) & 0x07;                      /* i8 funct */
        regy = -1;
        break;
       }
@@ -1450,13 +1437,7 @@ extended_mips16_next_pc (struct frame_info *frame, CORE_ADDR pc,
        CORE_ADDR offset;
        struct upk_mips16 upk;
        unpack_mips16 (gdbarch, pc, extension, insn, itype, &upk);
-       offset = upk.offset;
-       if (offset & 0x800)
-         {
-           offset &= 0xeff;
-           offset = -offset;
-         }
-       pc += (offset << 1) + 2;
+       pc += (upk.offset << 1) + 2;
        break;
       }
     case 3:                    /* JAL , JALX - Watch out, these are 32 bit
@@ -1476,7 +1457,7 @@ extended_mips16_next_pc (struct frame_info *frame, CORE_ADDR pc,
        struct upk_mips16 upk;
        int reg;
        unpack_mips16 (gdbarch, pc, extension, insn, ritype, &upk);
-       reg = get_frame_register_signed (frame, upk.regx);
+       reg = get_frame_register_signed (frame, mips16_to_32_reg[upk.regx]);
        if (reg == 0)
          pc += (upk.offset << 1) + 2;
        else
@@ -1488,7 +1469,7 @@ extended_mips16_next_pc (struct frame_info *frame, CORE_ADDR pc,
        struct upk_mips16 upk;
        int reg;
        unpack_mips16 (gdbarch, pc, extension, insn, ritype, &upk);
-       reg = get_frame_register_signed (frame, upk.regx);
+       reg = get_frame_register_signed (frame, mips16_to_32_reg[upk.regx]);
        if (reg != 0)
          pc += (upk.offset << 1) + 2;
        else
@@ -1520,21 +1501,10 @@ extended_mips16_next_pc (struct frame_info *frame, CORE_ADDR pc,
            int reg;
            upk.regx = (insn >> 8) & 0x07;
            upk.regy = (insn >> 5) & 0x07;
-           switch (upk.regy)
-             {
-             case 0:
-               reg = upk.regx;
-               break;
-             case 1:
-               reg = 31;
-               break;          /* Function return instruction.  */
-             case 2:
-               reg = upk.regx;
-               break;
-             default:
-               reg = 31;
-               break;          /* BOGUS Guess */
-             }
+           if ((upk.regy & 1) == 0)
+             reg = mips16_to_32_reg[upk.regx];
+           else
+             reg = 31;         /* Function return instruction.  */
            pc = get_frame_register_signed (frame, reg);
          }
        else