From eaa6a9a48207fecf3ebdba88314b0eedbdfce363 Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Fri, 2 Jan 2015 23:36:05 +0000 Subject: [PATCH] MIPS: Make the extracted stack offset signed in the prologue scanner Make the extracted stack offset signed in the standard MIPS prologue scanner, to simplify handling and make sure register offsets are correct in all cases, especially where $fp equals the virtual frame pointer (old GCC frames) and therefore offsets to save slots are negative. * mips-tdep.c (mips32_scan_prologue): Make the extracted stack offset signed. --- gdb/ChangeLog | 5 +++++ gdb/mips-tdep.c | 21 +++++++++++---------- 2 files changed, 16 insertions(+), 10 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 8b016dc..1d1e32c 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2015-01-02 Maciej W. Rozycki + + * mips-tdep.c (mips32_scan_prologue): Keep the extracted stack + offset signed. + 2015-01-02 Doug Evans * dwarf2read.c (setup_type_unit_groups): Remove outdated comment. diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c index 5cd66a1..bd8faef 100644 --- a/gdb/mips-tdep.c +++ b/gdb/mips-tdep.c @@ -3438,7 +3438,8 @@ restart: frame_offset = 0; for (cur_pc = start_pc; cur_pc < limit_pc; cur_pc += MIPS_INSN32_SIZE) { - unsigned long inst, high_word, low_word; + unsigned long inst, high_word; + long offset; int reg; this_non_prologue_insn = 0; @@ -3450,15 +3451,15 @@ restart: /* Save some code by pre-extracting some useful fields. */ high_word = (inst >> 16) & 0xffff; - low_word = inst & 0xffff; + offset = ((inst & 0xffff) ^ 0x8000) - 0x8000; reg = high_word & 0x1f; if (high_word == 0x27bd /* addiu $sp,$sp,-i */ || high_word == 0x23bd /* addi $sp,$sp,-i */ || high_word == 0x67bd) /* daddiu $sp,$sp,-i */ { - if (low_word & 0x8000) /* Negative stack adjustment? */ - frame_offset += 0x10000 - low_word; + if (offset < 0) /* Negative stack adjustment? */ + frame_offset -= offset; else /* Exit loop if a positive stack adjustment is found, which usually means that the stack cleanup code in the function @@ -3469,19 +3470,19 @@ restart: else if (((high_word & 0xFFE0) == 0xafa0) /* sw reg,offset($sp) */ && !regsize_is_64_bits) { - set_reg_offset (gdbarch, this_cache, reg, sp + low_word); + set_reg_offset (gdbarch, this_cache, reg, sp + offset); } else if (((high_word & 0xFFE0) == 0xffa0) /* sd reg,offset($sp) */ && regsize_is_64_bits) { /* Irix 6.2 N32 ABI uses sd instructions for saving $gp and $ra. */ - set_reg_offset (gdbarch, this_cache, reg, sp + low_word); + set_reg_offset (gdbarch, this_cache, reg, sp + offset); } else if (high_word == 0x27be) /* addiu $30,$sp,size */ { /* Old gcc frame, r30 is virtual frame pointer. */ - if ((long) low_word != frame_offset) - frame_addr = sp + low_word; + if (offset != frame_offset) + frame_addr = sp + offset; else if (this_frame && frame_reg == MIPS_SP_REGNUM) { unsigned alloca_adjust; @@ -3491,7 +3492,7 @@ restart: (this_frame, gdbarch_num_regs (gdbarch) + 30); frame_offset = 0; - alloca_adjust = (unsigned) (frame_addr - (sp + low_word)); + alloca_adjust = (unsigned) (frame_addr - (sp + offset)); if (alloca_adjust > 0) { /* FP > SP + frame_size. This may be because of @@ -3540,7 +3541,7 @@ restart: else if ((high_word & 0xFFE0) == 0xafc0 /* sw reg,offset($30) */ && !regsize_is_64_bits) { - set_reg_offset (gdbarch, this_cache, reg, frame_addr + low_word); + set_reg_offset (gdbarch, this_cache, reg, frame_addr + offset); } else if ((high_word & 0xFFE0) == 0xE7A0 /* swc1 freg,n($sp) */ || (high_word & 0xF3E0) == 0xA3C0 /* sx reg,n($s8) */ -- 2.7.4