[PATCH 8/9] gdb: final cleanup of various gdbarch_register_name methods

[Andrew Burgess <aburgess@redhat.com>]

Building on the previous commits, this commit goes through the various
gdbarch_register_name methods and removes all the remaining 'return
NULL' cases, I claim that these either couldn't be hit, or should be
returning the empty string.

In all cases the return of NULL was used if the register number being
passed to gdbarch_register_name was "invalid", i.e. negative, or
greater than the total number of declared registers.  I don't believe
either of these cases can occur, and the previous commit asserts that
this is the case.  As a result we can simplify the code by removing
these checks.  In many cases, where the register names are held in an
array, I was able to add a static assert that the array contains the
correct number of strings, after that, a direct access into the array
is fine.

I don't have any means of testing these changes.
---
 gdb/alpha-tdep.c      |  5 +----
 gdb/avr-tdep.c        |  6 ++----
 gdb/bpf-tdep.c        |  5 ++---
 gdb/cris-tdep.c       |  3 ++-
 gdb/frv-tdep.c        |  6 ------
 gdb/ft32-tdep.c       |  5 +----
 gdb/h8300-tdep.c      |  9 ++-------
 gdb/hppa-tdep.c       | 12 ++++--------
 gdb/iq2000-tdep.c     |  3 +--
 gdb/lm32-tdep.c       |  6 ++----
 gdb/m32r-tdep.c       |  5 +----
 gdb/m68hc11-tdep.c    |  5 +----
 gdb/m68k-tdep.c       |  9 +++------
 gdb/microblaze-tdep.c |  6 +++---
 gdb/mn10300-tdep.c    | 14 ++++++--------
 gdb/moxie-tdep.c      |  5 +----
 gdb/msp430-tdep.c     |  2 ++
 gdb/nds32-tdep.c      |  7 ++-----
 gdb/nios2-tdep.c      |  2 +-
 gdb/sh-tdep.c         | 33 +++++++++++----------------------
 gdb/sparc-tdep.c      |  8 ++------
 gdb/sparc64-tdep.c    |  8 ++------
 gdb/tic6x-tdep.c      |  3 ---
 gdb/tilegx-tdep.c     |  8 ++------
 gdb/v850-tdep.c       | 12 +++++-------
 gdb/vax-tdep.c        |  6 ++----
 gdb/xstormy16-tdep.c  |  9 ++-------
 gdb/xtensa-tdep.c     |  6 +-----
 gdb/z80-tdep.c        |  4 ++--
 29 files changed, 66 insertions(+), 146 deletions(-)

diff --git a/gdb/alpha-tdep.c b/gdb/alpha-tdep.c
index 44efc8e4bbb..8a5697939ec 100644
--- a/gdb/alpha-tdep.c
+++ b/gdb/alpha-tdep.c
@@ -99,10 +99,7 @@ alpha_register_name (struct gdbarch *gdbarch, int regno)
     "pc",   "",     "unique"
   };
 
-  if (regno < 0)
-    return NULL;
-  if (regno >= ARRAY_SIZE(register_names))
-    return NULL;
+  gdb_static_assert (ALPHA_NUM_REGS == ARRAY_SIZE (register_names));
   return register_names[regno];
 }
 
diff --git a/gdb/avr-tdep.c b/gdb/avr-tdep.c
index 693d563b911..f57dfac5e64 100644
--- a/gdb/avr-tdep.c
+++ b/gdb/avr-tdep.c
@@ -216,10 +216,8 @@ avr_register_name (struct gdbarch *gdbarch, int regnum)
     "SREG", "SP", "PC2",
     "pc"
   };
-  if (regnum < 0)
-    return NULL;
-  if (regnum >= (sizeof (register_names) / sizeof (*register_names)))
-    return NULL;
+  gdb_static_assert (ARRAY_SIZE (register_names)
+		     == (AVR_NUM_REGS + AVR_NUM_PSEUDO_REGS));
   return register_names[regnum];
 }
 
diff --git a/gdb/bpf-tdep.c b/gdb/bpf-tdep.c
index 4c085093632..b52fa5d5efb 100644
--- a/gdb/bpf-tdep.c
+++ b/gdb/bpf-tdep.c
@@ -93,9 +93,8 @@ static const char *bpf_register_names[] =
 static const char *
 bpf_register_name (struct gdbarch *gdbarch, int reg)
 {
-  if (reg >= 0 && reg < BPF_NUM_REGS)
-    return bpf_register_names[reg];
-  return NULL;
+  gdb_static_assert (ARRAY_SIZE (bpf_register_names) == BPF_NUM_REGS);
+  return bpf_register_names[reg];
 }
 
 /* Return the GDB type of register REGNUM.  */
diff --git a/gdb/cris-tdep.c b/gdb/cris-tdep.c
index a25490a3fa1..d1d85a557fb 100644
--- a/gdb/cris-tdep.c
+++ b/gdb/cris-tdep.c
@@ -1666,9 +1666,10 @@ cris_register_name (struct gdbarch *gdbarch, int regno)
     "r8",  "r9",  "r10", "r11", \
     "r12", "r13", "sp",  "pc" };
 
-  if (regno >= 0 && regno < NUM_GENREGS)
+  if (regno < NUM_GENREGS)
     {
       /* General register.  */
+      gdb_static_assert (ARRAY_SIZE (cris_genreg_names) == NUM_GENREGS);
       return cris_genreg_names[regno];
     }
   else if (regno >= NUM_GENREGS && regno < gdbarch_num_regs (gdbarch))
diff --git a/gdb/frv-tdep.c b/gdb/frv-tdep.c
index 8029080c043..866d5883876 100644
--- a/gdb/frv-tdep.c
+++ b/gdb/frv-tdep.c
@@ -269,12 +269,6 @@ set_variant_scratch_registers (frv_gdbarch_tdep *var)
 static const char *
 frv_register_name (struct gdbarch *gdbarch, int reg)
 {
-  if (reg < 0)
-    return "?toosmall?";
-
-  if (reg >= frv_num_regs + frv_num_pseudo_regs)
-    return "?toolarge?";
-
   frv_gdbarch_tdep *tdep = gdbarch_tdep<frv_gdbarch_tdep> (gdbarch);
   return tdep->register_names[reg];
 }
diff --git a/gdb/ft32-tdep.c b/gdb/ft32-tdep.c
index 500c691aa34..251baaf28ff 100644
--- a/gdb/ft32-tdep.c
+++ b/gdb/ft32-tdep.c
@@ -96,10 +96,7 @@ static const char *const ft32_register_names[] =
 static const char *
 ft32_register_name (struct gdbarch *gdbarch, int reg_nr)
 {
-  if (reg_nr < 0)
-    return NULL;
-  if (reg_nr >= FT32_NUM_REGS)
-    return NULL;
+  gdb_static_assert (ARRAY_SIZE (ft32_register_names) == FT32_NUM_REGS);
   return ft32_register_names[reg_nr];
 }
 
diff --git a/gdb/h8300-tdep.c b/gdb/h8300-tdep.c
index d453fce3319..0d1ab463ef3 100644
--- a/gdb/h8300-tdep.c
+++ b/gdb/h8300-tdep.c
@@ -934,13 +934,8 @@ static const char *
 h8300_register_name_common (const char *regnames[], int numregs,
 			    struct gdbarch *gdbarch, int regno)
 {
-  if (regno < 0
-      || regno >= numregs)
-    internal_error (__FILE__, __LINE__,
-		    _("h8300_register_name_common: illegal register number %d"),
-		    regno);
-  else
-    return regnames[regno];
+  gdb_assert (numregs == gdbarch_num_cooked_regs (gdbarch));
+  return regnames[regno];
 }
 
 static const char *
diff --git a/gdb/hppa-tdep.c b/gdb/hppa-tdep.c
index 91f9cecdcbc..7d5871c0e0f 100644
--- a/gdb/hppa-tdep.c
+++ b/gdb/hppa-tdep.c
@@ -632,10 +632,8 @@ hppa32_register_name (struct gdbarch *gdbarch, int i)
     "fr28",    "fr28R",  "fr29",   "fr29R",
     "fr30",   "fr30R",   "fr31",   "fr31R"
   };
-  if (i < 0 || i >= (sizeof (names) / sizeof (*names)))
-    return NULL;
-  else
-    return names[i];
+  gdb_static_assert (ARRAY_SIZE (names) == hppa32_num_regs);
+  return names[i];
 }
 
 static const char *
@@ -667,10 +665,8 @@ hppa64_register_name (struct gdbarch *gdbarch, int i)
     "fr24",    "fr25",   "fr26",   "fr27",
     "fr28",  "fr29",    "fr30",   "fr31"
   };
-  if (i < 0 || i >= (sizeof (names) / sizeof (*names)))
-    return NULL;
-  else
-    return names[i];
+  gdb_static_assert (ARRAY_SIZE (names) == hppa64_num_regs);
+  return names[i];
 }
 
 /* Map dwarf DBX register numbers to GDB register numbers.  */
diff --git a/gdb/iq2000-tdep.c b/gdb/iq2000-tdep.c
index e5fe1c62466..57498e879a1 100644
--- a/gdb/iq2000-tdep.c
+++ b/gdb/iq2000-tdep.c
@@ -135,8 +135,7 @@ iq2000_register_name (struct gdbarch *gdbarch, int regnum)
       "r30", "r31",
       "pc"
     };
-  if (regnum < 0 || regnum >= E_NUM_REGS)
-    return NULL;
+  gdb_static_assert (ARRAY_SIZE (names) == E_NUM_REGS);
   return names[regnum];
 }
 
diff --git a/gdb/lm32-tdep.c b/gdb/lm32-tdep.c
index af322511cfa..0394e1503ed 100644
--- a/gdb/lm32-tdep.c
+++ b/gdb/lm32-tdep.c
@@ -87,10 +87,8 @@ lm32_register_name (struct gdbarch *gdbarch, int reg_nr)
     "PC", "EID", "EBA", "DEBA", "IE", "IM", "IP"
   };
 
-  if ((reg_nr < 0) || (reg_nr >= ARRAY_SIZE (register_names)))
-    return NULL;
-  else
-    return register_names[reg_nr];
+  gdb_static_assert (ARRAY_SIZE (register_names) == SIM_LM32_NUM_REGS);
+  return register_names[reg_nr];
 }
 
 /* Return type of register.  */
diff --git a/gdb/m32r-tdep.c b/gdb/m32r-tdep.c
index 7edbd500bc5..297e5bf47b8 100644
--- a/gdb/m32r-tdep.c
+++ b/gdb/m32r-tdep.c
@@ -212,10 +212,7 @@ static const char * const m32r_register_names[] = {
 static const char *
 m32r_register_name (struct gdbarch *gdbarch, int reg_nr)
 {
-  if (reg_nr < 0)
-    return NULL;
-  if (reg_nr >= M32R_NUM_REGS)
-    return NULL;
+  gdb_static_assert (ARRAY_SIZE (m32r_register_names) == M32R_NUM_REGS);
   return m32r_register_names[reg_nr];
 }
 
diff --git a/gdb/m68hc11-tdep.c b/gdb/m68hc11-tdep.c
index f860ff81f2e..6277572adee 100644
--- a/gdb/m68hc11-tdep.c
+++ b/gdb/m68hc11-tdep.c
@@ -388,12 +388,9 @@ m68hc11_register_name (struct gdbarch *gdbarch, int reg_nr)
 
   if (reg_nr == HARD_PC_REGNUM && use_page_register (gdbarch))
     return "ppc";
-  
-  if (reg_nr < 0)
-    return NULL;
 
   if (reg_nr >= M68HC11_ALL_REGS)
-    return NULL;
+    return "";
 
   m68hc11_initialize_register_info ();
 
diff --git a/gdb/m68k-tdep.c b/gdb/m68k-tdep.c
index 9e59f5904c3..855fa1dd9a9 100644
--- a/gdb/m68k-tdep.c
+++ b/gdb/m68k-tdep.c
@@ -173,12 +173,9 @@ m68k_register_name (struct gdbarch *gdbarch, int regnum)
 {
   m68k_gdbarch_tdep *tdep = gdbarch_tdep<m68k_gdbarch_tdep> (gdbarch);
 
-  if (regnum < 0 || regnum >= ARRAY_SIZE (m68k_register_names))
-    internal_error (__FILE__, __LINE__,
-		    _("m68k_register_name: illegal register number %d"),
-		    regnum);
-  else if (regnum >= M68K_FP0_REGNUM && regnum <= M68K_FPI_REGNUM
-	   && tdep->fpregs_present == 0)
+  gdb_static_assert (ARRAY_SIZE (m68k_register_names) == M68K_NUM_REGS);
+  if (regnum >= M68K_FP0_REGNUM && regnum <= M68K_FPI_REGNUM
+      && tdep->fpregs_present == 0)
     return "";
   else
     return m68k_register_names[regnum];
diff --git a/gdb/microblaze-tdep.c b/gdb/microblaze-tdep.c
index 3525453deeb..55258ca32ae 100644
--- a/gdb/microblaze-tdep.c
+++ b/gdb/microblaze-tdep.c
@@ -92,9 +92,9 @@ static unsigned int microblaze_debug_flag = 0;
 static const char *
 microblaze_register_name (struct gdbarch *gdbarch, int regnum)
 {
-  if (regnum >= 0 && regnum < MICROBLAZE_NUM_REGS)
-    return microblaze_register_names[regnum];
-  return NULL;
+  gdb_static_assert (ARRAY_SIZE (microblaze_register_names)
+		     == MICROBLAZE_NUM_REGS);
+  return microblaze_register_names[regnum];
 }
 
 static struct type *
diff --git a/gdb/mn10300-tdep.c b/gdb/mn10300-tdep.c
index 22511d894d4..974d07dd998 100644
--- a/gdb/mn10300-tdep.c
+++ b/gdb/mn10300-tdep.c
@@ -250,12 +250,10 @@ mn10300_return_value (struct gdbarch *gdbarch, struct value *function,
 }
 
 static const char *
-register_name (int reg, const char **regs, long sizeof_regs)
+register_name (int reg, const char **regs, long num_regs)
 {
-  if (reg < 0 || reg >= sizeof_regs / sizeof (regs[0]))
-    return NULL;
-  else
-    return regs[reg];
+  gdb_assert (reg < num_regs);
+  return regs[reg];
 }
 
 static const char *
@@ -267,7 +265,7 @@ mn10300_generic_register_name (struct gdbarch *gdbarch, int reg)
     "", "", "", "", "", "", "", "",
     "", "", "", "", "", "", "", "fp"
   };
-  return register_name (reg, regs, sizeof regs);
+  return register_name (reg, regs, ARRAY_SIZE (regs));
 }
 
 
@@ -280,7 +278,7 @@ am33_register_name (struct gdbarch *gdbarch, int reg)
     "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
     "ssp", "msp", "usp", "mcrh", "mcrl", "mcvf", "", "", ""
   };
-  return register_name (reg, regs, sizeof regs);
+  return register_name (reg, regs, ARRAY_SIZE (regs));
 }
 
 static const char *
@@ -297,7 +295,7 @@ am33_2_register_name (struct gdbarch *gdbarch, int reg)
     "fs16", "fs17", "fs18", "fs19", "fs20", "fs21", "fs22", "fs23",
     "fs24", "fs25", "fs26", "fs27", "fs28", "fs29", "fs30", "fs31"
   };
-  return register_name (reg, regs, sizeof regs);
+  return register_name (reg, regs, ARRAY_SIZE (regs));
 }
 
 static struct type *
diff --git a/gdb/moxie-tdep.c b/gdb/moxie-tdep.c
index 77e1c33ecb6..86cfa6110d1 100644
--- a/gdb/moxie-tdep.c
+++ b/gdb/moxie-tdep.c
@@ -81,10 +81,7 @@ static const char * const moxie_register_names[] = {
 static const char *
 moxie_register_name (struct gdbarch *gdbarch, int reg_nr)
 {
-  if (reg_nr < 0)
-    return NULL;
-  if (reg_nr >= MOXIE_NUM_REGS)
-    return NULL;
+  gdb_static_assert (ARRAY_SIZE (moxie_register_names) == MOXIE_NUM_REGS);
   return moxie_register_names[reg_nr];
 }
 
diff --git a/gdb/msp430-tdep.c b/gdb/msp430-tdep.c
index 35bea093076..8f98965e8d0 100644
--- a/gdb/msp430-tdep.c
+++ b/gdb/msp430-tdep.c
@@ -196,6 +196,8 @@ msp430_register_name (struct gdbarch *gdbarch, int regnr)
     "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15"
   };
 
+  gdb_static_assert (ARRAY_SIZE (reg_names) == (MSP430_NUM_REGS
+						+ MSP430_NUM_PSEUDO_REGS));
   return reg_names[regnr];
 }
 
diff --git a/gdb/nds32-tdep.c b/gdb/nds32-tdep.c
index 5b555236d46..43d18c46d66 100644
--- a/gdb/nds32-tdep.c
+++ b/gdb/nds32-tdep.c
@@ -418,11 +418,8 @@ nds32_pseudo_register_name (struct gdbarch *gdbarch, int regnum)
   regnum -= gdbarch_num_regs (gdbarch);
 
   /* Currently, only FSRs could be defined as pseudo registers.  */
-  if (regnum < gdbarch_num_pseudo_regs (gdbarch))
-    return nds32_fsr_register_names[regnum];
-
-  warning (_("Unknown nds32 pseudo register %d."), regnum);
-  return NULL;
+  gdb_assert (regnum < gdbarch_num_pseudo_regs (gdbarch));
+  return nds32_fsr_register_names[regnum];
 }
 
 /* Implement the "pseudo_register_read" gdbarch method.  */
diff --git a/gdb/nios2-tdep.c b/gdb/nios2-tdep.c
index 0bad229b44a..14f593aba03 100644
--- a/gdb/nios2-tdep.c
+++ b/gdb/nios2-tdep.c
@@ -174,7 +174,7 @@ static const char *
 nios2_register_name (struct gdbarch *gdbarch, int regno)
 {
   /* Use mnemonic aliases for GPRs.  */
-  if (regno >= 0 && regno < NIOS2_NUM_REGS)
+  if (regno < NIOS2_NUM_REGS)
     return nios2_reg_names[regno];
   else
     return tdesc_register_name (gdbarch, regno);
diff --git a/gdb/sh-tdep.c b/gdb/sh-tdep.c
index 64b7ffa43da..739e4c9a9ba 100644
--- a/gdb/sh-tdep.c
+++ b/gdb/sh-tdep.c
@@ -115,8 +115,7 @@ sh_sh_register_name (struct gdbarch *gdbarch, int reg_nr)
     "pc", "pr", "gbr", "vbr", "mach", "macl", "sr"
   };
 
-  gdb_assert (reg_nr >= 0);
-  if (reg_nr >= (sizeof (register_names) / sizeof (*register_names)))
+  if (reg_nr >= ARRAY_SIZE (register_names))
     return "";
   return register_names[reg_nr];
 }
@@ -136,8 +135,7 @@ sh_sh3_register_name (struct gdbarch *gdbarch, int reg_nr)
     "r0b1", "r1b1", "r2b1", "r3b1", "r4b1", "r5b1", "r6b1", "r7b1",
   };
 
-  gdb_assert (reg_nr >= 0);
-  if (reg_nr >= (sizeof (register_names) / sizeof (*register_names)))
+  if (reg_nr >= ARRAY_SIZE (register_names))
     return "";
   return register_names[reg_nr];
 }
@@ -156,8 +154,7 @@ sh_sh3e_register_name (struct gdbarch *gdbarch, int reg_nr)
     "r0b0", "r1b0", "r2b0", "r3b0", "r4b0", "r5b0", "r6b0", "r7b0",
     "r0b1", "r1b1", "r2b1", "r3b1", "r4b1", "r5b1", "r6b1", "r7b1",
   };
-  gdb_assert (reg_nr >= 0);
-  if (reg_nr >= (sizeof (register_names) / sizeof (*register_names)))
+  if (reg_nr >= ARRAY_SIZE (register_names))
     return "";
   return register_names[reg_nr];
 }
@@ -173,8 +170,7 @@ sh_sh2e_register_name (struct gdbarch *gdbarch, int reg_nr)
     "fr0", "fr1", "fr2", "fr3", "fr4", "fr5", "fr6", "fr7",
     "fr8", "fr9", "fr10", "fr11", "fr12", "fr13", "fr14", "fr15",
   };
-  gdb_assert (reg_nr >= 0);
-  if (reg_nr >= (sizeof (register_names) / sizeof (*register_names)))
+  if (reg_nr >= ARRAY_SIZE (register_names))
     return "";
   return register_names[reg_nr];
 }
@@ -212,8 +208,7 @@ sh_sh2a_register_name (struct gdbarch *gdbarch, int reg_nr)
     /* double precision (pseudo) 68 - 75 */
     "dr0", "dr2", "dr4", "dr6", "dr8", "dr10", "dr12", "dr14",
   };
-  gdb_assert (reg_nr >= 0);
-  if (reg_nr >= (sizeof (register_names) / sizeof (*register_names)))
+  if (reg_nr >= ARRAY_SIZE (register_names))
     return "";
   return register_names[reg_nr];
 }
@@ -250,8 +245,7 @@ sh_sh2a_nofpu_register_name (struct gdbarch *gdbarch, int reg_nr)
     "bank",
     /* double precision (pseudo) 68 - 75: report blank, see below.  */
   };
-  gdb_assert (reg_nr >= 0);
-  if (reg_nr >= (sizeof (register_names) / sizeof (*register_names)))
+  if (reg_nr >= ARRAY_SIZE (register_names))
     return "";
   return register_names[reg_nr];
 }
@@ -269,8 +263,7 @@ sh_sh_dsp_register_name (struct gdbarch *gdbarch, int reg_nr)
     "", "",
     "rs", "re",
   };
-  gdb_assert (reg_nr >= 0);
-  if (reg_nr >= (sizeof (register_names) / sizeof (*register_names)))
+  if (reg_nr >= ARRAY_SIZE (register_names))
     return "";
   return register_names[reg_nr];
 }
@@ -289,8 +282,7 @@ sh_sh3_dsp_register_name (struct gdbarch *gdbarch, int reg_nr)
     "rs", "re", "", "", "", "", "", "",
     "r0b", "r1b", "r2b", "r3b", "r4b", "r5b", "r6b", "r7b",
   };
-  gdb_assert (reg_nr >= 0);
-  if (reg_nr >= (sizeof (register_names) / sizeof (*register_names)))
+  if (reg_nr >= ARRAY_SIZE (register_names))
     return "";
   return register_names[reg_nr];
 }
@@ -326,8 +318,7 @@ sh_sh4_register_name (struct gdbarch *gdbarch, int reg_nr)
     /* FIXME: missing XF */
     /* FIXME: missing XD */
   };
-  gdb_assert (reg_nr >= 0);
-  if (reg_nr >= (sizeof (register_names) / sizeof (*register_names)))
+  if (reg_nr >= ARRAY_SIZE (register_names))
     return "";
   return register_names[reg_nr];
 }
@@ -361,8 +352,7 @@ sh_sh4_nofpu_register_name (struct gdbarch *gdbarch, int reg_nr)
     /* vectors (pseudo) 76 - 79 -- not for nofpu target: report blank
        below.  */
   };
-  gdb_assert (reg_nr >= 0);
-  if (reg_nr >= (sizeof (register_names) / sizeof (*register_names)))
+  if (reg_nr >= ARRAY_SIZE (register_names))
     return "";
   return register_names[reg_nr];
 }
@@ -381,8 +371,7 @@ sh_sh4al_dsp_register_name (struct gdbarch *gdbarch, int reg_nr)
     "rs", "re", "", "", "", "", "", "",
     "r0b", "r1b", "r2b", "r3b", "r4b", "r5b", "r6b", "r7b",
   };
-  gdb_assert (reg_nr >= 0);
-  if (reg_nr >= (sizeof (register_names) / sizeof (*register_names)))
+  if (reg_nr >= ARRAY_SIZE (register_names))
     return "";
   return register_names[reg_nr];
 }
diff --git a/gdb/sparc-tdep.c b/gdb/sparc-tdep.c
index 0f5da2c393a..cce67babd13 100644
--- a/gdb/sparc-tdep.c
+++ b/gdb/sparc-tdep.c
@@ -398,12 +398,8 @@ sparc32_pseudo_register_name (struct gdbarch *gdbarch, int regnum)
 {
   regnum -= gdbarch_num_regs (gdbarch);
 
-  if (regnum < SPARC32_NUM_PSEUDO_REGS)
-    return sparc32_pseudo_register_names[regnum];
-
-  internal_error (__FILE__, __LINE__,
-		  _("sparc32_pseudo_register_name: bad register number %d"),
-		  regnum);
+  gdb_assert (regnum < SPARC32_NUM_PSEUDO_REGS);
+  return sparc32_pseudo_register_names[regnum];
 }
 
 /* Return the name of register REGNUM.  */
diff --git a/gdb/sparc64-tdep.c b/gdb/sparc64-tdep.c
index 5ca5f2dca8c..c42ae4ff94f 100644
--- a/gdb/sparc64-tdep.c
+++ b/gdb/sparc64-tdep.c
@@ -810,12 +810,8 @@ sparc64_pseudo_register_name (struct gdbarch *gdbarch, int regnum)
 {
   regnum -= gdbarch_num_regs (gdbarch);
 
-  if (regnum < SPARC64_NUM_PSEUDO_REGS)
-    return sparc64_pseudo_register_names[regnum];
-
-  internal_error (__FILE__, __LINE__,
-		  _("sparc64_pseudo_register_name: bad register number %d"),
-		  regnum);
+  gdb_assert (regnum < SPARC64_NUM_PSEUDO_REGS);
+  return sparc64_pseudo_register_names[regnum];
 }
 
 /* Return the name of register REGNUM.  */
diff --git a/gdb/tic6x-tdep.c b/gdb/tic6x-tdep.c
index 77576834733..38ea045f3ab 100644
--- a/gdb/tic6x-tdep.c
+++ b/gdb/tic6x-tdep.c
@@ -102,9 +102,6 @@ static const int arg_regs[] = { 4, 20, 6, 22, 8, 24, 10, 26, 12, 28 };
 static const char *
 tic6x_register_name (struct gdbarch *gdbarch, int regno)
 {
-  if (regno < 0)
-    return NULL;
-
   if (tdesc_has_registers (gdbarch_target_desc (gdbarch)))
     return tdesc_register_name (gdbarch, regno);
   else if (regno >= ARRAY_SIZE (tic6x_register_names))
diff --git a/gdb/tilegx-tdep.c b/gdb/tilegx-tdep.c
index 744aca96438..fac917c01a1 100644
--- a/gdb/tilegx-tdep.c
+++ b/gdb/tilegx-tdep.c
@@ -142,7 +142,7 @@ template_reverse_regs[TILEGX_NUM_PHYS_REGS] =
 static const char *
 tilegx_register_name (struct gdbarch *gdbarch, int regnum)
 {
-  static const char *const register_names[TILEGX_NUM_REGS] =
+  static const char *const register_names[] =
     {
       "r0",   "r1",   "r2",   "r3",   "r4",   "r5",   "r6",   "r7",
       "r8",   "r9",   "r10",  "r11",  "r12",  "r13",  "r14",  "r15",
@@ -155,11 +155,7 @@ tilegx_register_name (struct gdbarch *gdbarch, int regnum)
       "pc",   "faultnum",
     };
 
-  if (regnum < 0 || regnum >= TILEGX_NUM_REGS)
-    internal_error (__FILE__, __LINE__,
-		    "tilegx_register_name: invalid register number %d",
-		    regnum);
-
+  gdb_static_assert (TILEGX_NUM_REGS == ARRAY_SIZE (register_names));
   return register_names[regnum];
 }
 
diff --git a/gdb/v850-tdep.c b/gdb/v850-tdep.c
index a067bf74f16..6fc73cdc22e 100644
--- a/gdb/v850-tdep.c
+++ b/gdb/v850-tdep.c
@@ -312,8 +312,7 @@ v850_register_name (struct gdbarch *gdbarch, int regnum)
     "sr24", "sr25", "sr26", "sr27", "sr28", "sr29", "sr30", "sr31",
     "pc", "fp"
   };
-  if (regnum < 0 || regnum > E_NUM_OF_V850_REGS)
-    return "";
+  gdb_static_assert (E_NUM_OF_V850_REGS == ARRAY_SIZE (v850_reg_names));
   return v850_reg_names[regnum];
 }
 
@@ -332,8 +331,7 @@ v850e_register_name (struct gdbarch *gdbarch, int regnum)
     "sr24", "sr25", "sr26", "sr27", "sr28", "sr29", "sr30", "sr31",
     "pc", "fp"
   };
-  if (regnum < 0 || regnum > E_NUM_OF_V850E_REGS)
-    return "";
+  gdb_static_assert (E_NUM_OF_V850E_REGS == ARRAY_SIZE (v850e_reg_names));
   return v850e_reg_names[regnum];
 }
 
@@ -376,7 +374,7 @@ v850e2_register_name (struct gdbarch *gdbarch, int regnum)
     "", "", "", "", "", "", "", "",
     "", "", "", "fpspc"
   };
-  if (regnum < 0 || regnum >= E_NUM_OF_V850E2_REGS)
+  if (regnum >= E_NUM_OF_V850E2_REGS)
     return "";
   return v850e2_reg_names[regnum];
 }
@@ -479,8 +477,8 @@ v850e3v5_register_name (struct gdbarch *gdbarch, int regnum)
     "vr24", "vr25", "vr26", "vr27", "vr28", "vr29", "vr30", "vr31",
   };
 
-  if (regnum < 0 || regnum >= E_NUM_OF_V850E3V5_REGS)
-    return "";
+  gdb_static_assert (E_NUM_OF_V850E3V5_REGS
+		     == ARRAY_SIZE (v850e3v5_reg_names));
   return v850e3v5_reg_names[regnum];
 }
 
diff --git a/gdb/vax-tdep.c b/gdb/vax-tdep.c
index 6ad0dda021e..8de62124398 100644
--- a/gdb/vax-tdep.c
+++ b/gdb/vax-tdep.c
@@ -45,10 +45,8 @@ vax_register_name (struct gdbarch *gdbarch, int regnum)
     "ps",
   };
 
-  if (regnum >= 0 && regnum < ARRAY_SIZE (register_names))
-    return register_names[regnum];
-
-  return NULL;
+  gdb_static_assert (VAX_NUM_REGS == ARRAY_SIZE (register_names));
+  return register_names[regnum];
 }
 
 /* Return the GDB type object for the "standard" data type of data in
diff --git a/gdb/xstormy16-tdep.c b/gdb/xstormy16-tdep.c
index 10c0d3e6b1c..a5192f0fcf4 100644
--- a/gdb/xstormy16-tdep.c
+++ b/gdb/xstormy16-tdep.c
@@ -108,13 +108,8 @@ xstormy16_register_name (struct gdbarch *gdbarch, int regnum)
     "psw", "sp", "pc"
   };
 
-  if (regnum < 0 || regnum >= E_NUM_REGS)
-    internal_error (__FILE__, __LINE__,
-		    _("xstormy16_register_name: illegal register number %d"),
-		    regnum);
-  else
-    return register_names[regnum];
-
+  gdb_static_assert (ARRAY_SIZE (register_names) == E_NUM_REGS);
+  return register_names[regnum];
 }
 
 static struct type *
diff --git a/gdb/xtensa-tdep.c b/gdb/xtensa-tdep.c
index f881870e244..8f8195d647a 100644
--- a/gdb/xtensa-tdep.c
+++ b/gdb/xtensa-tdep.c
@@ -242,11 +242,7 @@ xtensa_register_name (struct gdbarch *gdbarch, int regnum)
   xtensa_gdbarch_tdep *tdep = gdbarch_tdep<xtensa_gdbarch_tdep> (gdbarch);
 
   /* Return the name stored in the register map.  */
-  if (regnum >= 0 && regnum < gdbarch_num_cooked_regs (gdbarch))
-    return tdep->regmap[regnum].name;
-
-  internal_error (__FILE__, __LINE__, _("invalid register %d"), regnum);
-  return 0;
+  return tdep->regmap[regnum].name;
 }
 
 /* Return the type of a register.  Create a new type, if necessary.  */
diff --git a/gdb/z80-tdep.c b/gdb/z80-tdep.c
index 684f08303c4..fe5cf993c01 100644
--- a/gdb/z80-tdep.c
+++ b/gdb/z80-tdep.c
@@ -167,10 +167,10 @@ static const char *z80_reg_names[] =
 static const char *
 z80_register_name (struct gdbarch *gdbarch, int regnum)
 {
-  if (regnum >= 0 && regnum < ARRAY_SIZE (z80_reg_names))
+  if (regnum < ARRAY_SIZE (z80_reg_names))
     return z80_reg_names[regnum];
 
-  return NULL;
+  return "";
 }
 
 /* Return the type of a register specified by the architecture.  Only
-- 
2.25.4