gdb:csky add support target-descriptions for CSKY arch

Registers in CSKY architecture included:
1. 32 gprs
2. 16 ars (alternative gprs used for quick interrupt)
3. hi, lo, pc
4. fr0~fr31, fcsr, fid, fesr
5. vr0~vr15
6. ((32 banks) * 32) cr regs (max 32 banks, 32 control regs a bank)

For register names:
Except over control registers, other registers, like gprs, hi, lo ...
are fixed names. Among the 32*32 control registers, some used registers
will have fixed names, others will have a default name "cpxcry". 'x'
refers to bank, y refers index in the bank(a control register in bank
4 with index 14 will has a default name cp4cr14).

For register numbers in GDB:
We assign a fixed number to each register in GDB, like:
r0~r31 with 0~31
hi, lo with 36, 37
fpu/vpu with 40~71
...
described in function csky_get_supported_register_by_index().

Function csky_get_supported_tdesc_registers_count():
To calculate the total number of registers that GDB can analyze,
including those with fixed names and those with default register names.

Function csky_get_supported_register_by_index():
To find a supported struct csky_supported_tdesc_register, return a
struct include name with regnum via index.

Arrays csky_supported_tdesc_feature_names[]:
Include all supported feature names in tdesc-xmls.

We use the information described above to load the register description
file of the target from the stub. When loading, do a little check that
whether the register description file contains SP, LR and PC.

1 files changed, 11 insertions, 3 deletions

diff --git a/gdb/csky-tdep.h b/gdb/csky-tdep.h
index d0e5fc0..adfe9fa 100644
--- a/gdb/csky-tdep.h
+++ b/gdb/csky-tdep.h
@@ -51,9 +51,10 @@ enum csky_regnum
 {
   CSKY_R0_REGNUM = 0, /* General registers.  */
   CSKY_R15_REGNUM = 15,
+  CSKY_HI_REGNUM = 36,
+  CSKY_LO_REGNUM = 37,
   CSKY_PC_REGNUM = 72,
-  CSKY_HI_REGNUM = 20,
-  CSKY_LO_REGNUM = 21,
+  CSKY_AR0_REGNUM = 73,
   CSKY_CR0_REGNUM = 89,
   CSKY_VBR_REGNUM = CSKY_CR0_REGNUM + 1,
   CSKY_EPSR_REGNUM = CSKY_CR0_REGNUM + 2,
@@ -63,7 +64,8 @@ enum csky_regnum
 
   /* Float register 0.  */
   CSKY_FR0_REGNUM = 40,
-  CSKY_VCR0_REGNUM = 121,
+  CSKY_FR16_REGNUM = 1172,
+  CSKY_FCR_REGNUM = 121,
   CSKY_MMU_REGNUM = 128,
   CSKY_PROFCR_REGNUM = 140,
   CSKY_PROFGR_REGNUM = 144,
@@ -93,6 +95,12 @@ enum csky_regnum
 /* ICE registers.  */
 #define CSKY_CRBANK_NUM_REGS 32
 
+/* Tdesc registers essential check.  */
+#define CSKY_TDESC_REGS_PC_NUMBERED             (1 << 0)
+#define CSKY_TDESC_REGS_SP_NUMBERED             (1 << 1)
+#define CSKY_TDESC_REGS_LR_NUMBERED             (1 << 2)
+#define CSKY_TDESC_REGS_ESSENTIAL_VALUE         (7)
+
 /* Number of processor registers w/o ICE registers.  */
 #define CSKY_NUM_REGS (CSKY_MAX_REGS - CSKY_CRBANK_NUM_REGS)