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Re: [RFA] sh-tdep.c: Follow up patch to implement two different ABIs


Corinna Vinschen writes:
 > Hi,
 > 
 > the below patch is a follow up patch which relies on the pending sh frame
 > stuff patch.  This patch now adds the ability to switch between two
 > different ABIs on the gdb command line, the "gcc" and the "renesas" ABI. 
 > The patch also implements the differences between these ABIs which changes
 > the way how arguments are passed and values are returned.  Additionally it
 > fixes the argument passing of doubles in the gcc ABI on sh variations with
 > FPU.  The changes in detail:


I think this patch has too much stuff in it. Can you change it to fix
the gcc abi (the fpu stuff), and then add the rest for the renesas
variant?



 > 
 > - Add the commands `set calling_convention <foo>' and
 >   `show calling_convention' with <foo> being one of "gcc" and "renesas".
 >   Default to "gcc".

Should be using hyphen, not underscore.  What happens if you have a
file compiled with renesas ABI but you set the calling convention to
the gcc (or vice versa)?  How are the abi supported by gcc? Is there a
-with-abi-renesas to be given when one compiles the tests? I.e. is it
possible to run the testsuite with the one specific abi?

 > 
 > - Differ between a fpu and a nofpu version of sh_use_struct_convention.
 >   The nofpu version behaves like the fpu version, except that it uses
 >   struct convention also for all types >= 8 bytes when the Renesas ABI
 >   is active.  This especially affects long longs and doubles which are
 >   then passed on the stack.
 > 
 > - The Renesas ABI passes the address in which structs have to be returned
 >   not in r2 as the gcc ABI, but instead this return address is pushed
 >   onto the stack after all arguments have been pushed.  This affects
 >   sh_extract_struct_value_address() as well as the sh_push_dummy_call*()
 >   functions.
 > 
 > - To simplify the sh_push_dummy_call*() functions, I created two helper
 >   functions which took the part of right-justifying values < 4 byte,
 >   called sh_justify_value_in_reg(), and to count the number of bytes
 >   to be allocated on stack for all arguments, called sh_stack_allocsize().
 > 
 > - Two new functions are now used to evaluate the next floating point
 >   register to use for an argument.  The tricky part with floats is
 >   that gcc and Renesas ABI are different in two situations:
 > 
 >   - gcc passes floats in little-endian mode using regsters criss-crossing,
 >     fr5, fr4, fr7, fr6, fr9, fr8 ...  In big-endian mode or in Renesas
 >     ABI, the order is simple fr4, fr5, fr6, ...
 > 
 >   - In both ABIs doubles are passed in even register pairs, fr4/fr5,
 >     fr6/fr7, ...  The difference is when a register is skipped to pass
 >     the next double.  Example:
 > 
 >       void foo(float a, double b, float c);
 > 
 >     In gcc ABI, a is passed in fr4, b then skips the odd-numbered fr5
 >     register, so it's passed in fr6/fr7 and c is then passed in the next
 >     free register, fr8.
 > 
 >     In Renesas ABI, a is passed in fr4, b is passed as in gcc ABI in
 >     fr6/fr7 but c is passed in the lowest unused register, in this example
 >     in fr5.
 > 
 > - In the Renesas ABI for CPUs with FPU, long longs are not passed in
 >   registers but on stack.
 > 
 > - The struct_return code in both sh_push_dummy_call*() functions is moved
 >   to the end of the function since it must be done after the argument
 >   passing for the Rensas ABI.
 > 
 > - I renamed the flag `odd_sized_struct' to a more descriptive name,
 >   `pass_on_stack' since the old name does in no way reflect how the
 >   decision about passing on stack or in register is actually made.  The
 >   actual decision is as follows:
 > 
 >   - On FPU CPUs, pass in registers unless the datatype is bigger than
 >     16 bytes.  Renesas ABI additionally passes long longs on the stack
 >     as well.
 > 
 >   - On non-FPU CPUs, doubles and long doubles are passed always on the stack.
 > 
 >   - On all CPUs, everything else is passed in registers until the argument
 >     registers are filled up, the remaining arguments are passed on stack. 
 >     If an argument doesn't fit entirely in the remaining registers, it's
 >     split between regs and stack as see fit.
 > 
 > - The code and comment that some data is sometimes passed in registers
 >   *and* stack simultaneously is dropped.  That's not how it works.
 >   Seems to be something sh5 specific but that's now in sh64-tdep.c.
 > 

Actually this is part of the original port as contributed by Steve
Chamberlain. Is this true of gcc or of the original hitachi abi?

 > - Also in sh_push_dummy_call*(), the code which adds 4 for every 4 bytes
 >   managed, is changed from e.g.
 > 
 >     len -= register_size (gdbarch, argreg);
 > 
 >   to
 >   
 >     len -= 4;
 > 
 >   The reason is that the original line is not exactly correct.  It adds the
 >   register_size of the *next* register, not the register actually filled
 >   with data.  Since all data and registers in question are 4 byte regs (and
 >   the target specific code should know that anyway), I've simplified the
 >   affected code.
 > 

I don't like to have harcoded register sizes, if argreg is wrong, is
there a way to get the correct parameter?


elena


 > 
 > Corinna
 > 
 > 
 > ChangeLog:
 > ==========
 > 
 > 	* sh-tdep.c (sh_cc_gcc): New static string.
 > 	(sh_cc_renesas): Ditto.
 > 	(sh_cc_enum): New array pointing to calling convention strings.
 > 	(sh_active_calling_convention): New variable pointing to
 > 	current active calling convention.
 > 	(sh_use_struct_convention_fpu): New function.
 > 	(sh_use_struct_convention_nofpu): New function.
 > 	(sh_use_struct_convention): Remove.  Superseeded by the previous
 > 	two functions.
 > 	(sh_extract_struct_value_address): Care for Renesas ABI.
 > 	(sh_justify_value_in_reg): New function.
 > 	(sh_stack_allocsize): Ditto.
 > 	(flt_argreg_array): New array used for floating point argument
 > 	passing.
 > 	(sh_init_flt_argreg): New function.
 > 	(sh_next_flt_argreg): Ditto.
 > 	(sh_push_dummy_call_fpu): Simplify. Rename "odd_sized_struct" to
 > 	"pass_on_stack". Use new helper functions.  Accomodate Renesas ABI.
 > 	Fix argument passing strategy.
 > 	(sh_push_dummy_call_nofpu): Ditto.
 > 	(sh_gdbarch_init): Accomodate new sh_use_struct_convention_fpu and
 > 	sh_use_struct_convention_nofpu functions.
 > 	(_initialize_sh_tdep): Initialize new "set calling_convention",
 > 	"show calling_convention" commands.
 > 
 > --- sh-tdep.c.AFTERPATCH2	2003-09-15 17:14:33.000000000 +0200
 > +++ sh-tdep.c	2003-09-16 18:17:39.000000000 +0200
 > @@ -55,6 +55,17 @@
 >  /* registers numbers shared with the simulator */
 >  #include "gdb/sim-sh.h"
 >  
 > +static const char sh_cc_gcc[] = "gcc";
 > +static const char sh_cc_renesas[] = "renesas";
 > +static const char *sh_cc_enum[] =
 > +{
 > +  sh_cc_gcc,
 > +  sh_cc_renesas,
 > +  NULL
 > +};
 > +
 > +static const char *sh_active_calling_convention = sh_cc_gcc;
 > +
 >  static void (*sh_show_regs) (void);
 >  
 >  #define SH_NUM_REGS 59
 > @@ -569,10 +580,25 @@ sh_skip_prologue (CORE_ADDR start_pc)
 >  
 >  /* Should call_function allocate stack space for a struct return?  */
 >  static int
 > -sh_use_struct_convention (int gcc_p, struct type *type)
 > +sh_use_struct_convention_fpu (int gcc_p, struct type *type)
 > +{
 > +  int len = TYPE_LENGTH (type);
 > +  int nelem = TYPE_NFIELDS (type);
 > +
 > +  return ((len != 1 && len != 2 && len != 4 && len != 8) || nelem != 1) &&
 > +	  (len != 8 || TYPE_LENGTH (TYPE_FIELD_TYPE (type, 0)) != 4);
 > +}
 > +
 > +static int
 > +sh_use_struct_convention_nofpu (int gcc_p, struct type *type)
 >  {
 >    int len = TYPE_LENGTH (type);
 >    int nelem = TYPE_NFIELDS (type);
 > +
 > +  /* The Renesas ABI returns long longs/doubles etc.  always on stack. */
 > +  if (sh_active_calling_convention == sh_cc_renesas && len >= 8)
 > +    return 1;
 > +
 >    return ((len != 1 && len != 2 && len != 4 && len != 8) || nelem != 1) &&
 >  	  (len != 8 || TYPE_LENGTH (TYPE_FIELD_TYPE (type, 0)) != 4);
 >  }
 > @@ -584,8 +610,13 @@ static CORE_ADDR
 >  sh_extract_struct_value_address (struct regcache *regcache)
 >  {
 >    ULONGEST addr;
 > -
 > -  regcache_cooked_read_unsigned (regcache, STRUCT_RETURN_REGNUM, &addr);
 > +  if (sh_active_calling_convention != sh_cc_renesas)
 > +    regcache_cooked_read_unsigned (regcache, STRUCT_RETURN_REGNUM, &addr);
 > +  else
 > +    {
 > +      regcache_cooked_read_unsigned (regcache, SP_REGNUM, &addr);
 > +      addr = read_memory_unsigned_integer (addr, 4);
 > +    }
 >    return addr;
 >  }
 >  
 > @@ -647,6 +678,102 @@ sh_frame_align (struct gdbarch *ignore, 
 >     not displace any of the other arguments passed in via registers R4
 >     to R7.   */
 >  
 > +/* Helper function to justify value in register according to endianess. */
 > +static char *
 > +sh_justify_value_in_reg (struct value *val, int len)
 > +{
 > +  static char valbuf[4];
 > +
 > +  memset (valbuf, 0, sizeof (valbuf));
 > +  if (len < 4)
 > +    {
 > +      /* value gets right-justified in the register or stack word */
 > +      if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
 > +	memcpy (valbuf + (4 - len), (char *) VALUE_CONTENTS (val), len);
 > +      else
 > +	memcpy (valbuf, (char *) VALUE_CONTENTS (val), len);
 > +      return valbuf;
 > +    }
 > +  return (char *) VALUE_CONTENTS (val);
 > +}
 > +
 > +/* Helper function to eval number of bytes to allocate on stack. */
 > +static CORE_ADDR
 > +sh_stack_allocsize (int nargs, struct value **args)
 > +{
 > +  int stack_alloc = 0;
 > +  while (nargs-- > 0)
 > +    stack_alloc += ((TYPE_LENGTH (VALUE_TYPE (args[nargs])) + 3) & ~3);
 > +  return stack_alloc;
 > +}
 > +
 > +/* Helper functions for getting the float arguments right.  Registers usage
 > +   depends on the ABI and the endianess.  The comments should enlighten how
 > +   it's intended to work. */
 > +
 > +/* This array stores which of the float arg registers are already in use. */
 > +static int flt_argreg_array[FLOAT_ARGLAST_REGNUM - FLOAT_ARG0_REGNUM + 1];
 > +
 > +/* This function just resets the above array to "no reg used so far". */
 > +static void
 > +sh_init_flt_argreg (void)
 > +{
 > +  memset (flt_argreg_array, 0, sizeof flt_argreg_array);
 > +}
 > +
 > +/* This function returns the next register to use for float arg passing.
 > +   It returns either a valid value between FLOAT_ARG0_REGNUM and
 > +   FLOAT_ARGLAST_REGNUM if a register is available, otherwise it returns 
 > +   FLOAT_ARGLAST_REGNUM + 1 to indicate that no register is available.
 > +
 > +   Note that register number 0 in flt_argreg_array corresponds with the
 > +   real float register fr4.  In contrast to FLOAT_ARG0_REGNUM (value is
 > +   29) the parity of the register number is preserved, which is important
 > +   for the double register passing test (see the "argreg & 1" test below). */
 > +static int
 > +sh_next_flt_argreg (int len)
 > +{
 > +  int argreg;
 > +
 > +  /* First search for the next free register. */
 > +  for (argreg = 0; argreg <= FLOAT_ARGLAST_REGNUM - FLOAT_ARG0_REGNUM; ++argreg)
 > +    if (!flt_argreg_array[argreg])
 > +      break;
 > +
 > +  /* No register left? */
 > +  if (argreg > FLOAT_ARGLAST_REGNUM - FLOAT_ARG0_REGNUM)
 > +    return FLOAT_ARGLAST_REGNUM + 1;
 > +
 > +  if (len == 8)
 > +    {
 > +      /* Doubles are always starting in a even register number. */
 > +      if (argreg & 1)
 > +        {
 > +	  /* In gcc ABI, the skipped register is lost for further argument
 > +	     passing now.  Not so in Renesas ABI. */
 > +	  if (sh_active_calling_convention != sh_cc_renesas)
 > +	    flt_argreg_array[argreg] = 1;
 > +
 > +	  ++argreg;
 > +
 > +	  /* No register left? */
 > +	  if (argreg > FLOAT_ARGLAST_REGNUM - FLOAT_ARG0_REGNUM)
 > +	    return FLOAT_ARGLAST_REGNUM + 1;
 > +	}
 > +      /* Also mark the next register as used. */
 > +      flt_argreg_array[argreg + 1] = 1;
 > +    }
 > +  else if (TARGET_BYTE_ORDER == BFD_ENDIAN_LITTLE
 > +	   && sh_active_calling_convention != sh_cc_renesas)
 > +    {
 > +      /* In little endian, gcc passes floats like this: f5, f4, f7, f6, ... */
 > +      if (!flt_argreg_array[argreg + 1])
 > +	++argreg;
 > +    }
 > +  flt_argreg_array[argreg] = 1;
 > +  return FLOAT_ARG0_REGNUM + argreg;
 > +}
 > +
 >  static CORE_ADDR
 >  sh_push_dummy_call_fpu (struct gdbarch *gdbarch, 
 >  			CORE_ADDR func_addr,
 > @@ -656,77 +783,61 @@ sh_push_dummy_call_fpu (struct gdbarch *
 >  			CORE_ADDR sp, int struct_return,
 >  			CORE_ADDR struct_addr)
 >  {
 > -  int stack_offset, stack_alloc;
 > -  int argreg, flt_argreg;
 > +  int stack_offset = 0;
 > +  int argreg = ARG0_REGNUM;
 > +  int flt_argreg;
 >    int argnum;
 >    struct type *type;
 >    CORE_ADDR regval;
 >    char *val;
 > -  char valbuf[4];
 >    int len;
 > -  int odd_sized_struct;
 > +  int pass_on_stack;
 >  
 >    /* first force sp to a 4-byte alignment */
 >    sp = sh_frame_align (gdbarch, sp);
 >  
 > -  if (struct_return)
 > -    regcache_cooked_write_unsigned (regcache,
 > -				    STRUCT_RETURN_REGNUM,
 > -				    struct_addr);
 > -
 > -  /* Now make sure there's space on the stack */
 > -  for (argnum = 0, stack_alloc = 0; argnum < nargs; argnum++)
 > -    stack_alloc += ((TYPE_LENGTH (VALUE_TYPE (args[argnum])) + 3) & ~3);
 > -  sp -= stack_alloc;		/* make room on stack for args */
 > +  /* make room on stack for args */
 > +  sp -= sh_stack_allocsize (nargs, args);
 > +
 > +  /* Initialize float argument mechanism. */
 > +  sh_init_flt_argreg ();
 >  
 >    /* Now load as many as possible of the first arguments into
 >       registers, and push the rest onto the stack.  There are 16 bytes
 >       in four registers available.  Loop thru args from first to last.  */
 > -
 > -  argreg = ARG0_REGNUM;
 > -  flt_argreg = FLOAT_ARG0_REGNUM;
 > -  for (argnum = 0, stack_offset = 0; argnum < nargs; argnum++)
 > +  for (argnum = 0; argnum < nargs; argnum++)
 >      {
 >        type = VALUE_TYPE (args[argnum]);
 >        len = TYPE_LENGTH (type);
 > -      memset (valbuf, 0, sizeof (valbuf));
 > -      if (len < 4)
 > -	{
 > -	  /* value gets right-justified in the register or stack word */
 > -	  if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
 > -	    memcpy (valbuf + (4 - len),
 > -		    (char *) VALUE_CONTENTS (args[argnum]), len);
 > -	  else
 > -	    memcpy (valbuf, (char *) VALUE_CONTENTS (args[argnum]), len);
 > -	  val = valbuf;
 > -	}
 > -      else
 > -	val = (char *) VALUE_CONTENTS (args[argnum]);
 > +      val = sh_justify_value_in_reg (args[argnum], len);
 > +
 > +      /* Some decisions have to be made how various types are handled.
 > +         This also differs in different ABIs. */
 > +      pass_on_stack = 0;
 > +      if (len > 16)
 > +	pass_on_stack = 1; /* Types bigger than 16 bytes are passed on stack. */
 > +      else if (sh_active_calling_convention == sh_cc_renesas
 > +	       && TYPE_CODE (type) == TYPE_CODE_INT && len == 8)
 > +	pass_on_stack = 1; /* So are long longs in renesas ABI */
 > +
 > +      /* Find out the next register to use for a floating point value. */
 > +      if (TYPE_CODE (type) == TYPE_CODE_FLT)
 > +        flt_argreg = sh_next_flt_argreg (len);
 >  
 > -      if (len > 4 && (len & 3) != 0)
 > -	odd_sized_struct = 1;	/* Such structs go entirely on stack.  */
 > -      else if (len > 16)
 > -	odd_sized_struct = 1;	/* So do aggregates bigger than 4 words.  */
 > -      else
 > -	odd_sized_struct = 0;
 >        while (len > 0)
 >  	{
 >  	  if ((TYPE_CODE (type) == TYPE_CODE_FLT 
 >  	       && flt_argreg > FLOAT_ARGLAST_REGNUM) 
 >  	      || argreg > ARGLAST_REGNUM
 > -	      || odd_sized_struct)
 > +	      || pass_on_stack)
 >  	    {			
 > -	      /* must go on the stack */
 >  	      write_memory (sp + stack_offset, val, 4);
 >  	      stack_offset += 4;
 >  	    }
 > -	  /* NOTE WELL!!!!!  This is not an "else if" clause!!!
 > -	     That's because some *&^%$ things get passed on the stack
 > -	     AND in the registers!   */
 > -	  if (TYPE_CODE (type) == TYPE_CODE_FLT &&
 > -	      flt_argreg > 0 && flt_argreg <= FLOAT_ARGLAST_REGNUM)
 > +	  else if (TYPE_CODE (type) == TYPE_CODE_FLT
 > +		   && flt_argreg <= FLOAT_ARGLAST_REGNUM)
 >  	    {
 > -	      /* Argument goes in a single-precision fp reg.  */
 > +	      /* Argument goes in a float argument register.  */
 >  	      regval = extract_unsigned_integer (val, register_size (gdbarch,
 >  								     argreg));
 >  	      regcache_cooked_write_unsigned (regcache, flt_argreg++, regval);
 > @@ -741,11 +852,25 @@ sh_push_dummy_call_fpu (struct gdbarch *
 >  	  /* Store the value 4 bytes at a time.  This means that things
 >  	     larger than 4 bytes may go partly in registers and partly
 >  	     on the stack.  */
 > -	  len -= register_size (gdbarch, argreg);
 > -	  val += register_size (gdbarch, argreg);
 > +	  len -= 4;
 > +	  val += 4;
 >  	}
 >      }
 >  
 > +  if (struct_return)
 > +    {
 > +      if (sh_active_calling_convention != sh_cc_renesas)
 > +	/* Using the gcc ABI, the "struct return pointer" pseudo-argument has
 > +	   its own dedicated register */
 > +	regcache_cooked_write_unsigned (regcache,
 > +					STRUCT_RETURN_REGNUM,
 > +					struct_addr);
 > +      else
 > +	/* If the function uses the renesas ABI, subtract another 4 bytes from
 > +	   the stack and store the struct return address there. */
 > +	write_memory_unsigned_integer (sp -= 4, 4, struct_addr);
 > +    }
 > +
 >    /* Store return address. */
 >    regcache_cooked_write_unsigned (regcache, PR_REGNUM, bp_addr);
 >  
 > @@ -764,69 +889,45 @@ sh_push_dummy_call_nofpu (struct gdbarch
 >  			  CORE_ADDR sp, int struct_return, 
 >  			  CORE_ADDR struct_addr)
 >  {
 > -  int stack_offset, stack_alloc;
 > -  int argreg;
 > +  int stack_offset = 0;
 > +  int argreg = ARG0_REGNUM;
 >    int argnum;
 >    struct type *type;
 >    CORE_ADDR regval;
 >    char *val;
 > -  char valbuf[4];
 >    int len;
 > -  int odd_sized_struct;
 > +  int pass_on_stack;
 >  
 >    /* first force sp to a 4-byte alignment */
 >    sp = sh_frame_align (gdbarch, sp);
 >  
 > -  if (struct_return)
 > -    regcache_cooked_write_unsigned (regcache,
 > -				    STRUCT_RETURN_REGNUM,
 > -				    struct_addr);
 > -
 > -  /* Now make sure there's space on the stack */
 > -  for (argnum = 0, stack_alloc = 0; argnum < nargs; argnum++)
 > -    stack_alloc += ((TYPE_LENGTH (VALUE_TYPE (args[argnum])) + 3) & ~3);
 > -  sp -= stack_alloc;		/* make room on stack for args */
 > +  /* make room on stack for args */
 > +  sp -= sh_stack_allocsize (nargs, args);
 >  
 >    /* Now load as many as possible of the first arguments into
 >       registers, and push the rest onto the stack.  There are 16 bytes
 >       in four registers available.  Loop thru args from first to last.  */
 > -
 > -  argreg = ARG0_REGNUM;
 > -  for (argnum = 0, stack_offset = 0; argnum < nargs; argnum++)
 > +  for (argnum = 0; argnum < nargs; argnum++)
 >      {
 >        type = VALUE_TYPE (args[argnum]);
 >        len = TYPE_LENGTH (type);
 > -      memset (valbuf, 0, sizeof (valbuf));
 > -      if (len < 4)
 > -	{
 > -	  /* value gets right-justified in the register or stack word */
 > -	  if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
 > -	    memcpy (valbuf + (4 - len),
 > -		    (char *) VALUE_CONTENTS (args[argnum]), len);
 > -	  else
 > -	    memcpy (valbuf, (char *) VALUE_CONTENTS (args[argnum]), len);
 > -	  val = valbuf;
 > -	}
 > -      else
 > -	val = (char *) VALUE_CONTENTS (args[argnum]);
 > +      val = sh_justify_value_in_reg (args[argnum], len);
 > +
 > +      /* Some decisions have to be made how various types are handled.
 > +         This also differs in different ABIs. */
 > +      pass_on_stack = 0;
 > +      if (TYPE_CODE (type) == TYPE_CODE_FLT && len > 4
 > +	  && sh_active_calling_convention == sh_cc_renesas)
 > +	pass_on_stack = 1; /* Renesas ABI pushes doubles entirely on stack. */
 >  
 > -      if (len > 4 && (len & 3) != 0)
 > -	odd_sized_struct = 1;	/* such structs go entirely on stack */
 > -      else
 > -	odd_sized_struct = 0;
 >        while (len > 0)
 >  	{
 > -	  if (argreg > ARGLAST_REGNUM
 > -	      || odd_sized_struct)
 > +	  if (argreg > ARGLAST_REGNUM || pass_on_stack)
 >  	    {			
 > -	      /* must go on the stack */
 >  	      write_memory (sp + stack_offset, val, 4);
 >  	      stack_offset += 4;
 >  	    }
 > -	  /* NOTE WELL!!!!!  This is not an "else if" clause!!!
 > -	     That's because some *&^%$ things get passed on the stack
 > -	     AND in the registers!   */
 > -	  if (argreg <= ARGLAST_REGNUM)
 > +	  else if (argreg <= ARGLAST_REGNUM)
 >  	    {			
 >  	      /* there's room in a register */
 >  	      regval = extract_unsigned_integer (val, register_size (gdbarch,
 > @@ -836,11 +937,25 @@ sh_push_dummy_call_nofpu (struct gdbarch
 >  	  /* Store the value 4 bytes at a time.  This means that things
 >  	     larger than 4 bytes may go partly in registers and partly
 >  	     on the stack.  */
 > -	  len -= register_size (gdbarch, argreg);
 > -	  val += register_size (gdbarch, argreg);
 > +	  len -= 4;
 > +	  val += 4;
 >  	}
 >      }
 >  
 > +  if (struct_return)
 > +    {
 > +      if (sh_active_calling_convention != sh_cc_renesas)
 > +	/* Using the gcc ABI, the "struct return pointer" pseudo-argument has
 > +	   its own dedicated register */
 > +	regcache_cooked_write_unsigned (regcache,
 > +					STRUCT_RETURN_REGNUM,
 > +					struct_addr);
 > +      else
 > +	/* If the function uses the renesas ABI, subtract another 4 bytes from
 > +	   the stack and store the struct return address there. */
 > +	write_memory_unsigned_integer (sp -= 4, 4, struct_addr);
 > +    }
 > +
 >    /* Store return address. */
 >    regcache_cooked_write_unsigned (regcache, PR_REGNUM, bp_addr);
 >  
 > @@ -2060,7 +2175,6 @@ sh_gdbarch_init (struct gdbarch_info inf
 >    set_gdbarch_print_registers_info (gdbarch, sh_print_registers_info);
 >  
 >    set_gdbarch_breakpoint_from_pc (gdbarch, sh_breakpoint_from_pc);
 > -  set_gdbarch_use_struct_convention (gdbarch, sh_use_struct_convention);
 >  
 >    set_gdbarch_print_insn (gdbarch, gdb_print_insn_sh);
 >    set_gdbarch_register_sim_regno (gdbarch, legacy_register_sim_regno);
 > @@ -2079,6 +2193,7 @@ sh_gdbarch_init (struct gdbarch_info inf
 >  
 >    set_gdbarch_push_dummy_code (gdbarch, sh_push_dummy_code);
 >    set_gdbarch_push_dummy_call (gdbarch, sh_push_dummy_call_nofpu);
 > +  set_gdbarch_use_struct_convention (gdbarch, sh_use_struct_convention_nofpu);
 >  
 >    set_gdbarch_frame_args_skip (gdbarch, 0);
 >    set_gdbarch_frameless_function_invocation (gdbarch,
 > @@ -2114,6 +2229,7 @@ sh_gdbarch_init (struct gdbarch_info inf
 >        set_gdbarch_store_return_value (gdbarch, sh3e_sh4_store_return_value);
 >        set_gdbarch_extract_return_value (gdbarch, sh3e_sh4_extract_return_value);
 >        set_gdbarch_push_dummy_call (gdbarch, sh_push_dummy_call_fpu);
 > +      set_gdbarch_use_struct_convention (gdbarch, sh_use_struct_convention_fpu);
 >        break;
 >  
 >      case bfd_mach_sh_dsp:
 > @@ -2135,6 +2251,7 @@ sh_gdbarch_init (struct gdbarch_info inf
 >        set_gdbarch_store_return_value (gdbarch, sh3e_sh4_store_return_value);
 >        set_gdbarch_extract_return_value (gdbarch, sh3e_sh4_extract_return_value);
 >        set_gdbarch_push_dummy_call (gdbarch, sh_push_dummy_call_fpu);
 > +      set_gdbarch_use_struct_convention (gdbarch, sh_use_struct_convention_fpu);
 >        break;
 >  
 >      case bfd_mach_sh3_dsp:
 > @@ -2152,6 +2269,7 @@ sh_gdbarch_init (struct gdbarch_info inf
 >        set_gdbarch_store_return_value (gdbarch, sh3e_sh4_store_return_value);
 >        set_gdbarch_extract_return_value (gdbarch, sh3e_sh4_extract_return_value);
 >        set_gdbarch_push_dummy_call (gdbarch, sh_push_dummy_call_fpu);
 > +      set_gdbarch_use_struct_convention (gdbarch, sh_use_struct_convention_fpu);
 >        break;
 >  
 >      default:
 > @@ -2178,4 +2296,11 @@ _initialize_sh_tdep (void)
 >    gdbarch_register (bfd_arch_sh, sh_gdbarch_init, NULL);
 >  
 >    add_com ("regs", class_vars, sh_show_regs_command, "Print all registers");
 > +
 > +  add_show_from_set (
 > +    add_set_enum_cmd ("calling_convention", class_vars, sh_cc_enum,
 > +		      &sh_active_calling_convention,
 > +		      "Set calling convention used when calling target "
 > +		      "functions from GDB.",
 > +		      &setlist), &showlist);
 >  }
 > 
 > -- 
 > Corinna Vinschen
 > Cygwin Developer
 > Red Hat, Inc.


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