From mboxrd@z Thu Jan 1 00:00:00 1970 From: Don Howard To: Daniel Jacobowitz Cc: Subject: Re: [RFA] mips fp register display Date: Fri, 22 Jun 2001 10:26:00 -0000 Message-id: References: <20010621160131.A27435@nevyn.them.org> X-SW-Source: 2001-06/msg00380.html On Thu, 21 Jun 2001, Daniel Jacobowitz wrote: > On Thu, Jun 21, 2001 at 03:42:10PM -0700, Don Howard wrote: > > > > This is a patch for an obscure mips fp register display problem. 32 bit mips > > chips support 64 bit float operations using two fp registers. 64 bit mips > > chips provide a backward compatiblity mode where 64 bit float ops are also > > supported using 2 float regsiters -- 32 bits stored in each of the 2 64bit fp > > regs. > > > > This patch addresses insight as well as cli gdb. Insight is not 100% correct: > > single precision floats are displayed in double format =( (cli gdb displays > > both float and double). I can change REGISTER_VIRTUAL_TYPE() to try to guess > > the the intended type (builtin_type_{float,double}), but that is really not > > the right place to fix this problem. > > > > > > 2001-06-21 Don Howard > > > > > > * mips-tdep.c (mips2_read_fp_register): New function. Reads a > > 64-bit float value stored as two 32-bit fragments in consecutive > > float registers. > > (mips2_fp_compat): New function. Determine if a MIPS3 or later > > cpu is operating in MIPS{1,2} float-compat mode. > > (mips_get_saved_register): Modified to use new > > mips2-compat float support. > > (mips_print_register): Modified to display 64-bit float regs in > > single and double precision. > > I see why this is necessary, but it doesn't address the problem I was > talking about. I also don't think it's really the right solution. > If you look a few lines higher in mips_print_register, you see: > > /* If an even floating point register, also print as double. */ > if (TYPE_CODE (REGISTER_VIRTUAL_TYPE (regnum)) == TYPE_CODE_FLT > && !((regnum - FP0_REGNUM) & 1)) > if (REGISTER_RAW_SIZE (regnum) == 4) /* this would be silly on MIPS64 or N32 (Irix 6) */ > { > char dbuffer[2 * MAX_REGISTER_RAW_SIZE]; > > read_relative_register_raw_bytes (regnum, dbuffer); > read_relative_register_raw_bytes (regnum + 1, dbuffer + MIPS_REGSIZE); > REGISTER_CONVERT_TO_TYPE (regnum, builtin_type_double, dbuffer); > > printf_filtered ("(d%d: ", regnum - FP0_REGNUM); > val_print (builtin_type_double, dbuffer, 0, 0, > gdb_stdout, 0, 1, 0, Val_pretty_default); > printf_filtered ("); "); > } > fputs_filtered (REGISTER_NAME (regnum), gdb_stdout); > > Well, obviously it's not always silly on N32. Change the > if (REGISTER_RAW_SIZE (regnum) == 4) > to something like > if (mips_small_float_registers ()) > > On the other hand, I think that perhaps if FR is set > REGISTER_RAW_SIZE (regnum) ought to be 4. Isn't that what it means? It seems to me that REGISTER_VIRTUAL_SIZE() is the macro that should provide this info, as the raw register doesn't change. Neither of these check the FR bit. > > Also, we already have REGISTER_CONVERT_TO_TYPE. Rather than hacking in > a third or perhaps fourth copy of this sort of thing, why not extend > REGISTER_CONVERT_TO_TYPE? I would guess (I'm no authority though) that REGISTER_CONVERT_TO_VIRTUAL() and REGISTER_CONVERT_TO_RAW() might be better places to do this. I chose to implement a new read_fp_register() function so that insight could benifit from the fix also. print_register() and do_register_row() affect cli gdb only. -- -Don dhoward@redhat.com gdb engineering