class readable_regcache and pass readable_regcache to gdbarch pseudo_register_read and pseudo_register_read_value

pseudo registers are either from raw registers or memory, so
gdbarch methods pseudo_register_read and pseudo_register_read_value
should have regcache object which only have read methods.  In other
words, we should disallow writing to regcache in these two gdbarch
methods.  In order to apply this restriction, this patch adds a new
class readable_regcache, derived from reg_buffer, and it only has
raw_read and cooked_read methods.  regcache is derived from
readable_regcache.  This patch also passes readable_regcache instead of
regcache to gdbarch methods pseudo_register_read and
pseudo_register_read_value.

This patch moves raw_read* and cooked_read* methods to readable_regcache,
which is straightforward.  One thing not straightforward is that I split
regcache::xfer_part to readable_regcache::read_part and regcache::write_part,
because readable_regcache can only have methods to read.

readable_regcache is an abstract base class, and it has a pure virtual
function raw_update, because I don't want readable_regcache know where
these raw registers are from.  They can be from either the target
(readwrite regcache) or the regcache itself (readonly regcache).

gdb:

2018-02-21  Yao Qi  <yao.qi@linaro.org>

	* aarch64-tdep.c (aarch64_pseudo_register_read_value): Change
	parameter type to 'readable_regcache *'.
	* amd64-tdep.c (amd64_pseudo_register_read_value): Likewise.
	* arm-tdep.c (arm_neon_quad_read): Likewise.
	(arm_pseudo_read): Likewise.
	* avr-tdep.c (avr_pseudo_register_read): Likewise.
	* bfin-tdep.c (bfin_pseudo_register_read): Likewise.
	* frv-tdep.c (frv_pseudo_register_read): Likewise.
	* gdbarch.c: Re-generated.
	* gdbarch.h: Re-generated.
	* gdbarch.sh (pseudo_register_read): Change parameter type to
	'readable_regcache *'.
	(pseudo_register_read_value): Likewise.
	* h8300-tdep.c (pseudo_from_raw_register): Likewise.
	(h8300_pseudo_register_read): Likewise.
	* hppa-tdep.c (hppa_pseudo_register_read): Likewise.
	* i386-tdep.c (i386_mmx_regnum_to_fp_regnum): Likewise.
	(i386_pseudo_register_read_into_value): Likewise.
	(i386_pseudo_register_read_value): Likewise.
	* i386-tdep.h (i386_pseudo_register_read_into_value): Update
	declaration.
	* ia64-tdep.c (ia64_pseudo_register_read): Likewise.
	* m32c-tdep.c (m32c_raw_read): Likewise.
	(m32c_read_flg): Likewise.
	(m32c_banked_register): Likewise.
	(m32c_banked_read): Likewise.
	(m32c_sb_read): Likewise.
	(m32c_part_read): Likewise.
	(m32c_cat_read): Likewise.
	(m32c_r3r2r1r0_read): Likewise.
	(m32c_pseudo_register_read): Likewise.
	* m68hc11-tdep.c (m68hc11_pseudo_register_read): Likewise.
	* mep-tdep.c (mep_pseudo_cr32_read): Likewise.
	(mep_pseudo_cr64_read): Likewise.
	(mep_pseudo_register_read): Likewise.
	* mips-tdep.c (mips_pseudo_register_read): Likewise.
	* msp430-tdep.c (msp430_pseudo_register_read): Likewise.
	* nds32-tdep.c (nds32_pseudo_register_read): Likewise.
	* regcache.c (regcache::raw_read): Move it to readable_regcache.
	(regcache::cooked_read): Likewise.
	(regcache::cooked_read_value): Likewise.
	(regcache_cooked_read_signed):
	(regcache::cooked_read): Likewise.
	* regcache.h (readable_regcache): New class.
	(regcache): Inherit readable_regcache.  Move some methods to
	readable_regcache.
	* rl78-tdep.c (rl78_pseudo_register_read): Change
	parameter type to 'readable_regcache *'.
	* rs6000-tdep.c (do_regcache_raw_read): Remove.
	(e500_pseudo_register_read): Change parameter type to
	'readable_regcache *'.
	(dfp_pseudo_register_read): Likewise.
	(vsx_pseudo_register_read): Likewise.
	(efpr_pseudo_register_read): Likewise.
	* s390-tdep.c (s390_pseudo_register_read): Likewise.
	* sh-tdep.c (sh_pseudo_register_read): Likewise.
	* sh64-tdep.c (pseudo_register_read_portions): Likewise.
	(sh64_pseudo_register_read): Likewise.
	* sparc-tdep.c (sparc32_pseudo_register_read): Likewise.
	* sparc64-tdep.c (sparc64_pseudo_register_read): Likewise.
	* spu-tdep.c (spu_pseudo_register_read_spu): Likewise.
	(spu_pseudo_register_read): Likewise.
	* xtensa-tdep.c	(xtensa_register_read_masked): Likewise.
	(xtensa_pseudo_register_read): Likewise.

1 files changed, 10 insertions, 10 deletions

diff --git a/gdb/m32c-tdep.c b/gdb/m32c-tdep.c
index 45dc438..173e8a4 100644
--- a/gdb/m32c-tdep.c
+++ b/gdb/m32c-tdep.c
@@ -51,7 +51,7 @@ typedef enum register_status (m32c_write_reg_t) (struct m32c_reg *reg,
 						 const gdb_byte *buf);
 
 typedef enum register_status (m32c_read_reg_t) (struct m32c_reg *reg,
-						struct regcache *cache,
+						readable_regcache *cache,
 						gdb_byte *buf);
 
 struct m32c_reg
@@ -310,7 +310,7 @@ static m32c_write_reg_t m32c_r3r2r1r0_write;
 
 /* Copy the value of the raw register REG from CACHE to BUF.  */
 static enum register_status
-m32c_raw_read (struct m32c_reg *reg, struct regcache *cache, gdb_byte *buf)
+m32c_raw_read (struct m32c_reg *reg, readable_regcache *cache, gdb_byte *buf)
 {
   return cache->raw_read (reg->num, buf);
 }
@@ -329,7 +329,7 @@ m32c_raw_write (struct m32c_reg *reg, struct regcache *cache,
 
 /* Return the value of the 'flg' register in CACHE.  */
 static int
-m32c_read_flg (struct regcache *cache)
+m32c_read_flg (readable_regcache *cache)
 {
   struct gdbarch_tdep *tdep = gdbarch_tdep (cache->arch ());
   ULONGEST flg;
@@ -341,7 +341,7 @@ m32c_read_flg (struct regcache *cache)
 
 /* Evaluate the real register number of a banked register.  */
 static struct m32c_reg *
-m32c_banked_register (struct m32c_reg *reg, struct regcache *cache)
+m32c_banked_register (struct m32c_reg *reg, readable_regcache *cache)
 {
   return ((m32c_read_flg (cache) & reg->n) ? reg->ry : reg->rx);
 }
@@ -352,7 +352,7 @@ m32c_banked_register (struct m32c_reg *reg, struct regcache *cache)
    masked in REG->n set, then read REG->ry.  Otherwise, read
    REG->rx.  */
 static enum register_status
-m32c_banked_read (struct m32c_reg *reg, struct regcache *cache, gdb_byte *buf)
+m32c_banked_read (struct m32c_reg *reg, readable_regcache *cache, gdb_byte *buf)
 {
   struct m32c_reg *bank_reg = m32c_banked_register (reg, cache);
   return cache->raw_read (bank_reg->num, buf);
@@ -377,7 +377,7 @@ m32c_banked_write (struct m32c_reg *reg, struct regcache *cache,
 /* Move the value of SB from CACHE to BUF.  On bfd_mach_m32c, SB is a
    banked register; on bfd_mach_m16c, it's not.  */
 static enum register_status
-m32c_sb_read (struct m32c_reg *reg, struct regcache *cache, gdb_byte *buf)
+m32c_sb_read (struct m32c_reg *reg, readable_regcache *cache, gdb_byte *buf)
 {
   if (gdbarch_bfd_arch_info (reg->arch)->mach == bfd_mach_m16c)
     return m32c_raw_read (reg->rx, cache, buf);
@@ -442,7 +442,7 @@ m32c_find_part (struct m32c_reg *reg, int *offset_p, int *len_p)
    REG->type values, where higher indices refer to more significant
    bits, read the value of the REG->n'th element.  */
 static enum register_status
-m32c_part_read (struct m32c_reg *reg, struct regcache *cache, gdb_byte *buf)
+m32c_part_read (struct m32c_reg *reg, readable_regcache *cache, gdb_byte *buf)
 {
   int offset, len;
 
@@ -473,7 +473,7 @@ m32c_part_write (struct m32c_reg *reg, struct regcache *cache,
    concatenation of the values of the registers REG->rx and REG->ry,
    with REG->rx contributing the more significant bits.  */
 static enum register_status
-m32c_cat_read (struct m32c_reg *reg, struct regcache *cache, gdb_byte *buf)
+m32c_cat_read (struct m32c_reg *reg, readable_regcache *cache, gdb_byte *buf)
 {
   int high_bytes = TYPE_LENGTH (reg->rx->type);
   int low_bytes  = TYPE_LENGTH (reg->ry->type);
@@ -528,7 +528,7 @@ m32c_cat_write (struct m32c_reg *reg, struct regcache *cache,
    the concatenation (from most significant to least) of r3, r2, r1,
    and r0.  */
 static enum register_status
-m32c_r3r2r1r0_read (struct m32c_reg *reg, struct regcache *cache, gdb_byte *buf)
+m32c_r3r2r1r0_read (struct m32c_reg *reg, readable_regcache *cache, gdb_byte *buf)
 {
   struct gdbarch_tdep *tdep = gdbarch_tdep (reg->arch);
   int len = TYPE_LENGTH (tdep->r0->type);
@@ -590,7 +590,7 @@ m32c_r3r2r1r0_write (struct m32c_reg *reg, struct regcache *cache,
 
 static enum register_status
 m32c_pseudo_register_read (struct gdbarch *arch,
-			   struct regcache *cache,
+			   readable_regcache *cache,
 			   int cookednum,
 			   gdb_byte *buf)
 {