From 4c2051c6c94ae19b0f2ded3a2244ecbd4bfb11e4 Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Thu, 8 Dec 2011 18:55:48 +0000 Subject: [PATCH] * 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. --- gdb/ChangeLog | 9 +++++++ gdb/mips-tdep.c | 64 +++++++++++++------------------------------------ 2 files changed, 26 insertions(+), 47 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 5b1de6407b9..2fb4758e563 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,12 @@ +2011-12-08 Maciej W. Rozycki + + * 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 * objfiles.h (struct objfile): Remove obsolete comment. diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c index 64b7629b12b..0f9a4abe0ac 100644 --- 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 -- 2.30.2