[PATCH v2] gdb: xtensa: don't supply registers if they are not present

[Alexey Lapshin <alexey.lapshin@espressif.com>]

When parsing a core file on hardware configurations without the
zero-overhead loop option (e.g. ESP32-S2 chip), GDB used to assert
while trying to call 'raw_supply' for lbeg, lend, lcount registers,
even though they were not set.

This was because:
regnum == -1 was used to indicate "supply all registers"
lbeg_regnum == -1 was used to indicate "lbeg register not present"
regnum == lbeg_regnum check was considered successful

---
 gdb/xtensa-tdep.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/gdb/xtensa-tdep.c b/gdb/xtensa-tdep.c
index 092ae088932..66e5baae7a5 100644
--- a/gdb/xtensa-tdep.c
+++ b/gdb/xtensa-tdep.c
@@ -801,6 +801,11 @@ xtensa_register_reggroup_p (struct gdbarch
*gdbarch,
     return 1;
 }
 
+static inline bool
+is_reg_raw_supplied (int check_regnum, int regnum)
+{
+  return check_regnum > 0 && (regnum == check_regnum || regnum == -1);
+}
 
 /* Supply register REGNUM from the buffer specified by GREGS and LEN
    in the general-purpose register set REGSET to register cache
@@ -824,22 +829,22 @@ xtensa_supply_gregset (const struct regset
*regset,
     rc->raw_supply (gdbarch_pc_regnum (gdbarch), (char *) &regs->pc);
   if (regnum == gdbarch_ps_regnum (gdbarch) || regnum == -1)
     rc->raw_supply (gdbarch_ps_regnum (gdbarch), (char *) &regs->ps);
-  if (regnum == tdep->wb_regnum || regnum == -1)
+  if (is_reg_raw_supplied (tdep->wb_regnum, regnum))
     rc->raw_supply (tdep->wb_regnum,
 		    (char *) &regs->windowbase);
-  if (regnum == tdep->ws_regnum || regnum == -1)
+  if (is_reg_raw_supplied (tdep->ws_regnum, regnum))
     rc->raw_supply (tdep->ws_regnum,
 		    (char *) &regs->windowstart);
-  if (regnum == tdep->lbeg_regnum || regnum == -1)
+  if (is_reg_raw_supplied (tdep->lbeg_regnum, regnum))
     rc->raw_supply (tdep->lbeg_regnum,
 		    (char *) &regs->lbeg);
-  if (regnum == tdep->lend_regnum || regnum == -1)
+  if (is_reg_raw_supplied (tdep->lend_regnum, regnum))
     rc->raw_supply (tdep->lend_regnum,
 		    (char *) &regs->lend);
-  if (regnum == tdep->lcount_regnum || regnum == -1)
+  if (is_reg_raw_supplied (tdep->lcount_regnum, regnum))
     rc->raw_supply (tdep->lcount_regnum,
 		    (char *) &regs->lcount);
-  if (regnum == tdep->sar_regnum || regnum == -1)
+  if (is_reg_raw_supplied (tdep->sar_regnum, regnum))
     rc->raw_supply (tdep->sar_regnum,
 		    (char *) &regs->sar);
   if (regnum >=tdep->ar_base
-- 
2.34.1