[RFC/RFA] MIPS extract_return_value

[Michael Snyder <msnyder@redhat.com>]

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Hey Andrew, Daniel,

I encountered another problem with 32/64 bit mips.  Don't know if this
is the right way to fix it, but it illustrates it (and fixes several
hundred failures).

The problem is that extract_return_value and store_return_value both
call return_value_location, but then one of them uses the raw register
and the other uses the cooked register (which are not the same size).
So the offset into the register cache, computed by
return_value_location, has to be wrong for one of them.

The simple-minded approach I've taken below is to add a parameter
to return_value_location, telling it whether to use the raw or cooked
registers.  I've only tested it on one architecture (isa64 with gcc
-mips32), so consider it more of a suggestion than a patch.






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2004-06-04  Michael Snyder  <msnyder@redhat.com>

	* mips-tdep.c (return_value_location): New parameter specifies
	whether to use raw registers (for store_return_value), or
	cooked registers (for extract_return_value).
	(mips_eabi_extract_return_value): Add new parameter for above.
	(mips_o64_extract_return_value): Ditto.
	(mips_eabi_store_return_value): Ditto.
	(mips_o64_store_return_value): Ditto.

Index: mips-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/mips-tdep.c,v
retrieving revision 1.294
diff -p -r1.294 mips-tdep.c
*** mips-tdep.c	3 May 2004 22:20:18 -0000	1.294
--- mips-tdep.c	4 Jun 2004 01:26:40 -0000
*************** struct return_value_word
*** 2638,2647 ****
    int buf_offset;
  };
  
  static void
  return_value_location (struct type *valtype,
  		       struct return_value_word *hi,
! 		       struct return_value_word *lo)
  {
    int len = TYPE_LENGTH (valtype);
    struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
--- 2638,2653 ----
    int buf_offset;
  };
  
+ enum {
+   STORE_RAW, 
+   EXTRACT_COOKED
+ };
+ 
  static void
  return_value_location (struct type *valtype,
  		       struct return_value_word *hi,
! 		       struct return_value_word *lo,
! 		       int storextract)
  {
    int len = TYPE_LENGTH (valtype);
    struct gdbarch_tdep *tdep = gdbarch_tdep (current_gdbarch);
*************** return_value_location (struct type *valt
*** 2663,2668 ****
--- 2669,2679 ----
  	  hi->reg_offset = lo->reg_offset;
  	  lo->reg = mips_regnum (current_gdbarch)->fp0 + 0;
  	  hi->reg = mips_regnum (current_gdbarch)->fp0 + 1;
+ 	  if (storextract == EXTRACT_COOKED)
+ 	    {
+ 	      lo->reg += NUM_REGS;
+ 	      hi->reg += NUM_REGS;
+ 	    }
  	  lo->len = 4;
  	  hi->len = 4;
  	}
*************** return_value_location (struct type *valt
*** 2676,2681 ****
--- 2687,2694 ----
  					       fp0) == 8
  			     && len == 4) ? 4 : 0);
  	  lo->reg = mips_regnum (current_gdbarch)->fp0;
+ 	  if (storextract == EXTRACT_COOKED)
+ 	    lo->reg += NUM_REGS;
  	  lo->len = len;
  	  lo->buf_offset = 0;
  	  hi->len = 0;
*************** return_value_location (struct type *valt
*** 2688,2693 ****
--- 2701,2709 ----
      {
        /* Locate a result possibly spread across two registers. */
        int regnum = 2;
+       if (storextract == EXTRACT_COOKED)
+ 	regnum += NUM_REGS;
+ 
        lo->reg = regnum + 0;
        hi->reg = regnum + 1;
        if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG
*************** mips_eabi_extract_return_value (struct t
*** 3042,3056 ****
  {
    struct return_value_word lo;
    struct return_value_word hi;
!   return_value_location (valtype, &hi, &lo);
  
    memcpy (valbuf + lo.buf_offset,
! 	  regbuf + DEPRECATED_REGISTER_BYTE (NUM_REGS + lo.reg) +
  	  lo.reg_offset, lo.len);
  
    if (hi.len > 0)
      memcpy (valbuf + hi.buf_offset,
! 	    regbuf + DEPRECATED_REGISTER_BYTE (NUM_REGS + hi.reg) +
  	    hi.reg_offset, hi.len);
  }
  
--- 3058,3072 ----
  {
    struct return_value_word lo;
    struct return_value_word hi;
!   return_value_location (valtype, &hi, &lo, EXTRACT_COOKED);
  
    memcpy (valbuf + lo.buf_offset,
! 	  regbuf + DEPRECATED_REGISTER_BYTE (lo.reg) +
  	  lo.reg_offset, lo.len);
  
    if (hi.len > 0)
      memcpy (valbuf + hi.buf_offset,
! 	    regbuf + DEPRECATED_REGISTER_BYTE (hi.reg) +
  	    hi.reg_offset, hi.len);
  }
  
*************** mips_eabi_store_return_value (struct typ
*** 3063,3069 ****
    char raw_buffer[MAX_REGISTER_SIZE];
    struct return_value_word lo;
    struct return_value_word hi;
!   return_value_location (valtype, &hi, &lo);
  
    memset (raw_buffer, 0, sizeof (raw_buffer));
    memcpy (raw_buffer + lo.reg_offset, valbuf + lo.buf_offset, lo.len);
--- 3079,3085 ----
    char raw_buffer[MAX_REGISTER_SIZE];
    struct return_value_word lo;
    struct return_value_word hi;
!   return_value_location (valtype, &hi, &lo, STORE_RAW);
  
    memset (raw_buffer, 0, sizeof (raw_buffer));
    memcpy (raw_buffer + lo.reg_offset, valbuf + lo.buf_offset, lo.len);
*************** mips_o64_extract_return_value (struct ty
*** 4191,4205 ****
  {
    struct return_value_word lo;
    struct return_value_word hi;
!   return_value_location (valtype, &hi, &lo);
  
    memcpy (valbuf + lo.buf_offset,
! 	  regbuf + DEPRECATED_REGISTER_BYTE (NUM_REGS + lo.reg) +
  	  lo.reg_offset, lo.len);
  
    if (hi.len > 0)
      memcpy (valbuf + hi.buf_offset,
! 	    regbuf + DEPRECATED_REGISTER_BYTE (NUM_REGS + hi.reg) +
  	    hi.reg_offset, hi.len);
  }
  
--- 4207,4221 ----
  {
    struct return_value_word lo;
    struct return_value_word hi;
!   return_value_location (valtype, &hi, &lo, EXTRACT_COOKED);
  
    memcpy (valbuf + lo.buf_offset,
! 	  regbuf + DEPRECATED_REGISTER_BYTE (lo.reg) +
  	  lo.reg_offset, lo.len);
  
    if (hi.len > 0)
      memcpy (valbuf + hi.buf_offset,
! 	    regbuf + DEPRECATED_REGISTER_BYTE (hi.reg) +
  	    hi.reg_offset, hi.len);
  }
  
*************** mips_o64_store_return_value (struct type
*** 4209,4215 ****
    char raw_buffer[MAX_REGISTER_SIZE];
    struct return_value_word lo;
    struct return_value_word hi;
!   return_value_location (valtype, &hi, &lo);
  
    memset (raw_buffer, 0, sizeof (raw_buffer));
    memcpy (raw_buffer + lo.reg_offset, valbuf + lo.buf_offset, lo.len);
--- 4225,4231 ----
    char raw_buffer[MAX_REGISTER_SIZE];
    struct return_value_word lo;
    struct return_value_word hi;
!   return_value_location (valtype, &hi, &lo, STORE_RAW);
  
    memset (raw_buffer, 0, sizeof (raw_buffer));
    memcpy (raw_buffer + lo.reg_offset, valbuf + lo.buf_offset, lo.len);