diff --git a/gdb/dwarf2-frame.c b/gdb/dwarf2-frame.c
index 8fb2ac7..eb9f09c 100644
--- a/gdb/dwarf2-frame.c
+++ b/gdb/dwarf2-frame.c
@@ -292,7 +292,7 @@ read_addr_from_reg (void *baton, int reg)
  {
    struct frame_info *this_frame = (struct frame_info *) baton;
    struct gdbarch *gdbarch = get_frame_arch (this_frame);
-  int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, reg);
+  int regnum = dwarf2_reg_to_regnum_or_error (gdbarch, reg);

    return address_from_register (regnum, this_frame);
  }
@@ -304,7 +304,7 @@ get_reg_value (void *baton, struct type *type, int reg)
  {
    struct frame_info *this_frame = (struct frame_info *) baton;
    struct gdbarch *gdbarch = get_frame_arch (this_frame);
-  int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, reg);
+  int regnum = dwarf2_reg_to_regnum_or_error (gdbarch, reg);

    return value_from_register (type, regnum, this_frame);
  }
@@ -936,11 +936,7 @@ dwarf2_fetch_cfa_info (struct gdbarch *gdbarch,  
CORE_ADDR pc,
      {
      case CFA_REG_OFFSET:
        {
-	int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, fs.regs.cfa_reg);
-
-	if (regnum == -1)
-	  error (_("Unable to access DWARF register number %d"),
-		 (int) fs.regs.cfa_reg); /* FIXME */
+	int regnum = dwarf2_reg_to_regnum_or_error (gdbarch, fs.regs.cfa_reg);

  	*regnum_out = regnum;
  	if (fs.armcc_cfa_offsets_reversed)
@@ -1324,8 +1320,8 @@ dwarf2_frame_prev_register (struct frame_info  
*this_frame, void **this_cache,
        return frame_unwind_got_memory (this_frame, regnum, addr);

      case DWARF2_FRAME_REG_SAVED_REG:
-      realnum
-	= gdbarch_dwarf2_reg_to_regnum (gdbarch, cache->reg[regnum].loc.reg);
+      realnum = dwarf2_reg_to_regnum_or_error
+	(gdbarch, cache->reg[regnum].loc.reg);
        return frame_unwind_got_register (this_frame, regnum, realnum);

      case DWARF2_FRAME_REG_SAVED_EXP:
@@ -1368,7 +1364,7 @@ dwarf2_frame_prev_register (struct frame_info  
*this_frame, void **this_cache,

      case DWARF2_FRAME_REG_RA_OFFSET:
        addr = cache->reg[regnum].loc.offset;
-      regnum = gdbarch_dwarf2_reg_to_regnum
+      regnum = dwarf2_reg_to_regnum_or_error
  	(gdbarch, cache->retaddr_reg.loc.reg);
        addr += get_frame_register_unsigned (this_frame, regnum);
        return frame_unwind_got_address (this_frame, regnum, addr);
diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
index d8e432e..b8f172d 100644
--- a/gdb/dwarf2loc.c
+++ b/gdb/dwarf2loc.c
@@ -312,7 +312,7 @@ dwarf_expr_read_addr_from_reg (void *baton, int  
dwarf_regnum)
  {
    struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
    struct gdbarch *gdbarch = get_frame_arch (debaton->frame);
-  int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, dwarf_regnum);
+  int regnum = dwarf2_reg_to_regnum_or_error (gdbarch, dwarf_regnum);

    return address_from_register (regnum, debaton->frame);
  }
@@ -324,7 +324,7 @@ dwarf_expr_get_reg_value (void *baton, struct type  
*type, int dwarf_regnum)
  {
    struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
    struct gdbarch *gdbarch = get_frame_arch (debaton->frame);
-  int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, dwarf_regnum);
+  int regnum = dwarf2_reg_to_regnum_or_error (gdbarch, dwarf_regnum);

    return value_from_register (type, regnum, debaton->frame);
  }
@@ -1682,40 +1682,31 @@ read_pieced_value (struct value *v)
  	case DWARF_VALUE_REGISTER:
  	  {
  	    struct gdbarch *arch = get_frame_arch (frame);
-	    int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, p->v.regno);
+	    int gdb_regnum = dwarf2_reg_to_regnum_or_error (arch, p->v.regno);
+	    int optim, unavail;
+	    int reg_offset = source_offset;

-	    if (gdb_regnum != -1)
+	    if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG
+		&& this_size < register_size (arch, gdb_regnum))
  	      {
-		int optim, unavail;
-		int reg_offset = source_offset;
-
-		if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG
-		    && this_size < register_size (arch, gdb_regnum))
-		  {
-		    /* Big-endian, and we want less than full size.  */
-		    reg_offset = register_size (arch, gdb_regnum) - this_size;
-		    /* We want the lower-order THIS_SIZE_BITS of the bytes
-		       we extract from the register.  */
-		    source_offset_bits += 8 * this_size - this_size_bits;
-		 }
-
-		if (!get_frame_register_bytes (frame, gdb_regnum, reg_offset,
-					       this_size, buffer,
-					       &optim, &unavail))
-		  {
-		    /* Just so garbage doesn't ever shine through.  */
-		    memset (buffer, 0, this_size);
-
-		    if (optim)
-		      mark_value_bits_optimized_out (v, offset, this_size_bits);
-		    if (unavail)
-		      mark_value_bits_unavailable (v, offset, this_size_bits);
-		  }
+		/* Big-endian, and we want less than full size.  */
+		reg_offset = register_size (arch, gdb_regnum) - this_size;
+		/* We want the lower-order THIS_SIZE_BITS of the bytes
+		   we extract from the register.  */
+		source_offset_bits += 8 * this_size - this_size_bits;
  	      }
-	    else
+
+	    if (!get_frame_register_bytes (frame, gdb_regnum, reg_offset,
+					   this_size, buffer,
+					   &optim, &unavail))
  	      {
-		error (_("Unable to access DWARF register number %s"),
-		       paddress (arch, p->v.regno));
+		/* Just so garbage doesn't ever shine through.  */
+		memset (buffer, 0, this_size);
+
+		if (optim)
+		  mark_value_bits_optimized_out (v, offset, this_size_bits);
+		if (unavail)
+		  mark_value_bits_unavailable (v, offset, this_size_bits);
  	      }
  	  }
  	  break;
@@ -1874,52 +1865,43 @@ write_pieced_value (struct value *to, struct value  
*from)
  	case DWARF_VALUE_REGISTER:
  	  {
  	    struct gdbarch *arch = get_frame_arch (frame);
-	    int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, p->v.regno);
+	    int gdb_regnum = dwarf2_reg_to_regnum_or_error (arch, p->v.regno);
+	    int reg_offset = dest_offset;

-	    if (gdb_regnum != -1)
+	    if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG
+		&& this_size <= register_size (arch, gdb_regnum))
  	      {
-		int reg_offset = dest_offset;
+		/* Big-endian, and we want less than full size.  */
+		reg_offset = register_size (arch, gdb_regnum) - this_size;
+	      }

-		if (gdbarch_byte_order (arch) == BFD_ENDIAN_BIG
-		    && this_size <= register_size (arch, gdb_regnum))
-		  {
-		    /* Big-endian, and we want less than full size.  */
-		    reg_offset = register_size (arch, gdb_regnum) - this_size;
-		  }
+	    if (need_bitwise)
+	      {
+		int optim, unavail;

-		if (need_bitwise)
+		if (!get_frame_register_bytes (frame, gdb_regnum, reg_offset,
+					       this_size, buffer,
+					       &optim, &unavail))
  		  {
-		    int optim, unavail;
-
-		    if (!get_frame_register_bytes (frame, gdb_regnum, reg_offset,
-						   this_size, buffer,
-						   &optim, &unavail))
-		      {
-			if (optim)
-			  throw_error (OPTIMIZED_OUT_ERROR,
-				       _("Can't do read-modify-write to "
-					 "update bitfield; containing word "
-					 "has been optimized out"));
-			if (unavail)
-			  throw_error (NOT_AVAILABLE_ERROR,
-				       _("Can't do read-modify-write to update "
-					 "bitfield; containing word "
-					 "is unavailable"));
-		      }
-		    copy_bitwise (buffer, dest_offset_bits,
-				  contents, source_offset_bits,
-				  this_size_bits,
-				  bits_big_endian);
+		    if (optim)
+		      throw_error (OPTIMIZED_OUT_ERROR,
+				   _("Can't do read-modify-write to "
+				     "update bitfield; containing word "
+				     "has been optimized out"));
+		    if (unavail)
+		      throw_error (NOT_AVAILABLE_ERROR,
+				   _("Can't do read-modify-write to update "
+				     "bitfield; containing word "
+				     "is unavailable"));
  		  }
-
-		put_frame_register_bytes (frame, gdb_regnum, reg_offset,
-					  this_size, source_buffer);
-	      }
-	    else
-	      {
-		error (_("Unable to write to DWARF register number %s"),
-		       paddress (arch, p->v.regno));
+		copy_bitwise (buffer, dest_offset_bits,
+			      contents, source_offset_bits,
+			      this_size_bits,
+			      bits_big_endian);
  	      }
+
+	    put_frame_register_bytes (frame, gdb_regnum, reg_offset,
+				      this_size, source_buffer);
  	  }
  	  break;
  	case DWARF_VALUE_MEMORY:
@@ -2260,30 +2242,28 @@ dwarf2_evaluate_loc_desc_full (struct type *type,  
struct frame_info *frame,
  	    struct gdbarch *arch = get_frame_arch (frame);
  	    int dwarf_regnum
  	      = longest_to_int (value_as_long (dwarf_expr_fetch (ctx, 0)));
-	    int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, dwarf_regnum);
+	    int gdb_regnum = dwarf2_reg_to_regnum_or_error
+	      (arch, dwarf_regnum);

  	    if (byte_offset != 0)
  	      error (_("cannot use offset on synthetic pointer to register"));
  	    do_cleanups (value_chain);
-	   if (gdb_regnum == -1)
-	      error (_("Unable to access DWARF register number %d"),
-		     dwarf_regnum);
-	   retval = value_from_register (type, gdb_regnum, frame);
-	   if (value_optimized_out (retval))
-	     {
-	       struct value *tmp;
-
-	       /* This means the register has undefined value / was
-		  not saved.  As we're computing the location of some
-		  variable etc. in the program, not a value for
-		  inspecting a register ($pc, $sp, etc.), return a
-		  generic optimized out value instead, so that we show
-		  <optimized out> instead of <not saved>.  */
-	       do_cleanups (value_chain);
-	       tmp = allocate_value (type);
-	       value_contents_copy (tmp, 0, retval, 0, TYPE_LENGTH (type));
-	       retval = tmp;
-	     }
+	    retval = value_from_register (type, gdb_regnum, frame);
+	    if (value_optimized_out (retval))
+	      {
+		struct value *tmp;
+
+		/* This means the register has undefined value / was
+		   not saved.  As we're computing the location of some
+		   variable etc. in the program, not a value for
+		   inspecting a register ($pc, $sp, etc.), return a
+		   generic optimized out value instead, so that we show
+		   <optimized out> instead of <not saved>.  */
+		do_cleanups (value_chain);
+		tmp = allocate_value (type);
+		value_contents_copy (tmp, 0, retval, 0, TYPE_LENGTH (type));
+		retval = tmp;
+	      }
  	  }
  	  break;

@@ -2777,11 +2757,17 @@ unimplemented (unsigned int op)
  /* See dwarf2loc.h.  */

  int
-dwarf2_reg_to_regnum_or_error (struct gdbarch *arch, int dwarf_reg)
+dwarf2_reg_to_regnum_or_error (struct gdbarch *arch, ULONGEST dwarf_reg)
  {
-  int reg = gdbarch_dwarf2_reg_to_regnum (arch, dwarf_reg);
+  int reg;
+
+  if (dwarf_reg > INT_MAX)
+    error (_("Unable to access DWARF register number %s"),
+	   pulongest (dwarf_reg));
+  reg = gdbarch_dwarf2_reg_to_regnum (arch, (int) dwarf_reg);
    if (reg == -1)
-    error (_("Unable to access DWARF register number %d"), dwarf_reg);
+    error (_("Unable to access DWARF register number %s"),
+	   pulongest (dwarf_reg));
    return reg;
  }

@@ -3572,7 +3558,17 @@ locexpr_regname (struct gdbarch *gdbarch, int  
dwarf_regnum)
  {
    int regnum;

+  /* This doesn't use gdbarch_dwarf2_reg_to_regnum_or_error on purpose.
+     We'd rather print *something* here than throw an error.  */
    regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, dwarf_regnum);
+  /* gdbarch_register_name may just return "", return something more
+     descriptive for bad register numbers.  */
+  if (regnum == -1)
+    {
+      /* The text is output as "$bad_register_number".
+	 That is why we use the underscores.  */
+      return _("bad_register_number");
+    }
    return gdbarch_register_name (gdbarch, regnum);
  }

diff --git a/gdb/dwarf2loc.h b/gdb/dwarf2loc.h
index f3630ac..41916eb 100644
--- a/gdb/dwarf2loc.h
+++ b/gdb/dwarf2loc.h
@@ -287,8 +287,12 @@ extern struct call_site_chain *call_site_find_chain  
(struct gdbarch *gdbarch,
     ARCH is the architecture.
     DWARF_REG is the register.
     This will throw an exception if the DWARF register cannot be
-   translated to an architecture register.  */
+   translated to an architecture register.
+   This takes a ULONGEST instead of an int because some callers actually  
have
+   a ULONGEST.  Negative values passed as ints will still be flagged as
+   invalid.  */

-extern int dwarf2_reg_to_regnum_or_error (struct gdbarch *arch, int  
dwarf_reg);
+extern int dwarf2_reg_to_regnum_or_error (struct gdbarch *arch,
+					  ULONGEST dwarf_reg);

  #endif /* dwarf2loc.h */
diff --git a/gdb/testsuite/gdb.dwarf2/bad-regnum.c  
b/gdb/testsuite/gdb.dwarf2/bad-regnum.c
new file mode 100644
index 0000000..35230f2
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/bad-regnum.c
@@ -0,0 +1,22 @@
+/* Copyright 2015 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.   
*/
+
+int
+main ()
+{
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.dwarf2/bad-regnum.exp  
b/gdb/testsuite/gdb.dwarf2/bad-regnum.exp
new file mode 100644
index 0000000..7356adb
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/bad-regnum.exp
@@ -0,0 +1,64 @@
+# Copyright 2015 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0
+}
+
+standard_testfile bad-regnum.c bad-regnum-dw.S
+
+# Make some DWARF for the test.
+set asm_file [standard_output_file $srcfile2]
+Dwarf::assemble $asm_file {
+    cu {} {
+	DW_TAG_compile_unit {
+	    {DW_AT_language @DW_LANG_C}
+	    {DW_AT_name     bad-regnum-dw.c}
+	    {DW_AT_comp_dir /tmp}
+	} {
+	    declare_labels integer_label
+
+	    integer_label: DW_TAG_base_type {
+		{DW_AT_byte_size 4 DW_FORM_sdata}
+		{DW_AT_encoding  @DW_ATE_signed}
+		{DW_AT_name      integer}
+	    }
+
+	    DW_TAG_variable {
+		{DW_AT_name foo}
+		{DW_AT_type :$integer_label}
+		{DW_AT_location {
+		    DW_OP_regx 2147483647
+		} SPECIAL_expr}
+		{external 1 flag}
+	    }
+	}
+    }
+}
+
+if { [prepare_for_testing ${testfile}.exp ${testfile} \
+	  [list $srcfile $asm_file] {nodebug}] } {
+    return -1
+}
+
+if ![runto_main] {
+    return -1
+}
+
+gdb_test "info addr foo" \
+    "Symbol \"foo\" is warning: Unmapped DWARF Register #2147483647  
encountered.\[\r\n\]+a variable in \\\$bad_register_number."
diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
index 515334e..df7a36d 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -836,6 +836,10 @@ namespace eval Dwarf {
  		    _op .${_cu_addr_size}byte [lindex $line 1]
  		}

+		DW_OP_regx {
+		    _op .uleb128 [lindex $line 1]
+		}
+
  		DW_OP_pick -
  		DW_OP_const1u -
  		DW_OP_const1s {
