Refactor struct trad_frame_saved_regs

The following patch drops the overloading going on with the trad_frame_saved_reg
struct and defines a new struct with a KIND enum and a union of different
fields.

The new struct looks like this:

struct trad_frame_saved_reg
 {
  setters/getters

  ...

private:

  trad_frame_saved_reg_kind m_kind;

  union {
    LONGEST value;
    int realreg;
    LONGEST addr;
    const gdb_byte *value_bytes;
  } m_reg;
};

And the enums look like this:

/* Describes the kind of encoding a stored register has.  */
enum class trad_frame_saved_reg_kind
{
  /* Register value is unknown.  */
  UNKNOWN = 0,
  /* Register value is a constant.  */
  VALUE,
  /* Register value is in another register.  */
  REALREG,
  /* Register value is at an address.  */
  ADDR,
  /* Register value is a sequence of bytes.  */
  VALUE_BYTES
};

The patch also adds setters/getters and updates all the users of the old
struct.

It is worth mentioning that due to the previous overloaded nature of the
fields, some tdep files like to store negative offsets and indexes in the ADDR
field, so I kept the ADDR as LONGEST instead of CORE_ADDR. Those cases may
be better supported by a new enum entry.

I have not addressed those cases in this patch to prevent unwanted breakage,
given I have no way to test some of the targets. But it would be nice to
clean those up eventually.

The change to frame-unwind.* is to constify the parameter being passed to the
unwinding functions, given we now accept a "const gdb_byte *" for value bytes.

Tested on aarch64-linux/Ubuntu 20.04/18.04 and by building GDB with
--enable-targets=all.

gdb/ChangeLog:

2021-01-04  Luis Machado  <luis.machado@linaro.org>

	Update all users of trad_frame_saved_reg to use the new member
	functions.

	Remote all struct keywords from declarations of trad_frame_saved_reg
	types, except on forward declarations.

	* aarch64-tdep.c: Update.
	* alpha-mdebug-tdep.c: Update.
	* alpha-tdep.c: Update.
	* arc-tdep.c: Update.
	* arm-tdep.c: Update.
	* avr-tdep.c: Update.
	* cris-tdep.c: Update.
	* csky-tdep.c: Update.
	* frv-tdep.c: Update.
	* hppa-linux-tdep.c: Update.
	* hppa-tdep.c: Update.
	* hppa-tdep.h: Update.
	* lm32-tdep.c: Update.
	* m32r-linux-tdep.c: Update.
	* m32r-tdep.c: Update.
	* m68hc11-tdep.c: Update.
	* mips-tdep.c: Update.
	* moxie-tdep.c: Update.
	* riscv-tdep.c: Update.
	* rs6000-tdep.c: Update.
	* s390-linux-tdep.c: Update.
	* s390-tdep.c: Update.
	* score-tdep.c: Update.
	* sparc-netbsd-tdep.c: Update.
	* sparc-sol2-tdep.c: Update.
	* sparc64-fbsd-tdep.c: Update.
	* sparc64-netbsd-tdep.c: Update.
	* sparc64-obsd-tdep.c: Update.
	* sparc64-sol2-tdep.c: Update.
	* tilegx-tdep.c: Update.
	* v850-tdep.c: Update.
	* vax-tdep.c: Update.

	* frame-unwind.c (frame_unwind_got_bytes): Make parameter const.
	* frame-unwind.h (frame_unwind_got_bytes): Likewise.

	* trad-frame.c: Update.
	Remove TF_REG_* enum.
	(trad_frame_alloc_saved_regs): Add a static assertion to check for
	a trivially-constructible struct.
	(trad_frame_reset_saved_regs): Adjust to use member function.
	(trad_frame_value_p): Likewise.
	(trad_frame_addr_p): Likewise.
	(trad_frame_realreg_p): Likewise.
	(trad_frame_value_bytes_p): Likewise.
	(trad_frame_set_value): Likewise.
	(trad_frame_set_realreg): Likewise.
	(trad_frame_set_addr): Likewise.
	(trad_frame_set_unknown): Likewise.
	(trad_frame_set_value_bytes): Likewise.
	(trad_frame_get_prev_register): Likewise.
	* trad-frame.h: Update.
	(trad_frame_saved_reg_kind): New enum.
	(struct trad_frame_saved_reg) <addr, realreg, data>: Remove.
	<m_kind, m_reg>: New member fields.
	<set_value, set_realreg, set_addr, set_unknown, set_value_bytes>
	<kind, value, realreg, addr, value_bytes, is_value, is_realreg>
	<is_addr, is_unknown, is_value_bytes>: New member functions.

1 files changed, 23 insertions, 24 deletions

diff --git a/gdb/cris-tdep.c b/gdb/cris-tdep.c
index 19d0373..63ce803 100644
--- a/gdb/cris-tdep.c
+++ b/gdb/cris-tdep.c
@@ -305,7 +305,7 @@ struct cris_unwind_cache
   int leaf_function;
 
   /* Table indicating the location of each and every register.  */
-  struct trad_frame_saved_reg *saved_regs;
+  trad_frame_saved_reg *saved_regs;
 };
 
 static struct cris_unwind_cache *
@@ -354,18 +354,18 @@ cris_sigtramp_frame_unwind_cache (struct frame_info *this_frame,
       /* R0 to R13 are stored in reverse order at offset (2 * 4) in 
 	 struct pt_regs.  */
       for (i = 0; i <= 13; i++)
-	info->saved_regs[i].addr = addr + ((15 - i) * 4);
+	info->saved_regs[i].set_addr (addr + ((15 - i) * 4));
 
-      info->saved_regs[MOF_REGNUM].addr = addr + (16 * 4);
-      info->saved_regs[DCCR_REGNUM].addr = addr + (17 * 4);
-      info->saved_regs[SRP_REGNUM].addr = addr + (18 * 4);
+      info->saved_regs[MOF_REGNUM].set_addr (addr + (16 * 4));
+      info->saved_regs[DCCR_REGNUM].set_addr (addr + (17 * 4));
+      info->saved_regs[SRP_REGNUM].set_addr (addr + (18 * 4));
       /* Note: IRP is off by 2 at this point.  There's no point in correcting
 	 it though since that will mean that the backtrace will show a PC 
 	 different from what is shown when stopped.  */
-      info->saved_regs[IRP_REGNUM].addr = addr + (19 * 4);
+      info->saved_regs[IRP_REGNUM].set_addr (addr + (19 * 4));
       info->saved_regs[gdbarch_pc_regnum (gdbarch)]
 	= info->saved_regs[IRP_REGNUM];
-      info->saved_regs[gdbarch_sp_regnum (gdbarch)].addr = addr + (24 * 4);
+      info->saved_regs[gdbarch_sp_regnum (gdbarch)].set_addr (addr + (24 * 4));
     }
   else
     {
@@ -373,17 +373,17 @@ cris_sigtramp_frame_unwind_cache (struct frame_info *this_frame,
       /* R0 to R13 are stored in order at offset (1 * 4) in 
 	 struct pt_regs.  */
       for (i = 0; i <= 13; i++)
-	info->saved_regs[i].addr = addr + ((i + 1) * 4);
-
-      info->saved_regs[ACR_REGNUM].addr = addr + (15 * 4);
-      info->saved_regs[SRS_REGNUM].addr = addr + (16 * 4);
-      info->saved_regs[MOF_REGNUM].addr = addr + (17 * 4);
-      info->saved_regs[SPC_REGNUM].addr = addr + (18 * 4);
-      info->saved_regs[CCS_REGNUM].addr = addr + (19 * 4);
-      info->saved_regs[SRP_REGNUM].addr = addr + (20 * 4);
-      info->saved_regs[ERP_REGNUM].addr = addr + (21 * 4);
-      info->saved_regs[EXS_REGNUM].addr = addr + (22 * 4);
-      info->saved_regs[EDA_REGNUM].addr = addr + (23 * 4);
+	info->saved_regs[i].set_addr (addr + ((i + 1) * 4));
+
+      info->saved_regs[ACR_REGNUM].set_addr (addr + (15 * 4));
+      info->saved_regs[SRS_REGNUM].set_addr (addr + (16 * 4));
+      info->saved_regs[MOF_REGNUM].set_addr (addr + (17 * 4));
+      info->saved_regs[SPC_REGNUM].set_addr (addr + (18 * 4));
+      info->saved_regs[CCS_REGNUM].set_addr (addr + (19 * 4));
+      info->saved_regs[SRP_REGNUM].set_addr (addr + (20 * 4));
+      info->saved_regs[ERP_REGNUM].set_addr (addr + (21 * 4));
+      info->saved_regs[EXS_REGNUM].set_addr (addr + (22 * 4));
+      info->saved_regs[EDA_REGNUM].set_addr (addr + (23 * 4));
 
       /* FIXME: If ERP is in a delay slot at this point then the PC will
 	 be wrong at this point.  This problem manifests itself in the
@@ -395,8 +395,7 @@ cris_sigtramp_frame_unwind_cache (struct frame_info *this_frame,
       info->saved_regs[gdbarch_pc_regnum (gdbarch)]
 	= info->saved_regs[ERP_REGNUM];
 
-      info->saved_regs[gdbarch_sp_regnum (gdbarch)].addr
-	= addr + (25 * 4);
+      info->saved_regs[gdbarch_sp_regnum (gdbarch)].set_addr (addr + (25 * 4));
     }
   
   return info;
@@ -1229,7 +1228,7 @@ cris_scan_prologue (CORE_ADDR pc, struct frame_info *this_frame,
 	 the next frame.  */
       this_base = get_frame_register_unsigned (this_frame, CRIS_FP_REGNUM);
       info->base = this_base;
-      info->saved_regs[CRIS_FP_REGNUM].addr = info->base;
+      info->saved_regs[CRIS_FP_REGNUM].set_addr (info->base);
   
       /* The FP points at the last saved register.  Adjust the FP back
 	 to before the first saved register giving the SP.  */
@@ -1254,7 +1253,7 @@ cris_scan_prologue (CORE_ADDR pc, struct frame_info *this_frame,
 
   for (regno = regsave; regno >= 0; regno--)
     {
-      info->saved_regs[regno].addr = info->base + info->r8_offset - val;
+      info->saved_regs[regno].set_addr (info->base + info->r8_offset - val);
       val -= 4;
     }
 
@@ -1269,12 +1268,12 @@ cris_scan_prologue (CORE_ADDR pc, struct frame_info *this_frame,
       if (info->r8_offset == 0)
 	{
 	  /* R8 not pushed yet.  */
-	  info->saved_regs[SRP_REGNUM].addr = info->base;
+	  info->saved_regs[SRP_REGNUM].set_addr (info->base);
 	}
       else
 	{
 	  /* R8 pushed, but SP may or may not be moved to R8 yet.  */
-	  info->saved_regs[SRP_REGNUM].addr = info->base + 4;
+	  info->saved_regs[SRP_REGNUM].set_addr (info->base + 4);
 	}
     }