[COMMITTED,v2] pru: Named address space for R30/R31 I/O access

diff --git a/gcc/config/pru/constraints.md b/gcc/config/pru/constraints.md
index a31ae9318b8..1e0e703c394 100644
--- a/gcc/config/pru/constraints.md
+++ b/gcc/config/pru/constraints.md
@@ -34,6 +34,7 @@ 
 ;; The following constraints are intended for internal use only:
 ;;  Rmd0, Rms0, Rms1: Registers for MUL instruction operands.
 ;;  Rsib: Jump address register suitable for sibling calls.
+;;  Rrio: The R30 and R31 I/O registers.
 ;;  M: -255 to 0 (for converting ADD to SUB with suitable UBYTE OP2).
 ;;  N: -32768 to 32767 (16-bit signed integer).
 ;;  O: -128 to 127 (8-bit signed integer).
@@ -57,6 +58,10 @@  (define_register_constraint "Rms1" "MULSRC1_REGS"
   "@internal
   The multiply source 1 register.")
 
+(define_register_constraint "Rrio" "REGIO_REGS"
+  "@internal
+  The R30 and R31 I/O registers.")
+
 ;; Integer constraints.
 
 (define_constraint "I"
diff --git a/gcc/config/pru/predicates.md b/gcc/config/pru/predicates.md
index 469002f0567..1a4b98eb216 100644
--- a/gcc/config/pru/predicates.md
+++ b/gcc/config/pru/predicates.md
@@ -121,6 +121,25 @@  (define_predicate "pru_mulsrc1_operand"
   return 0;
 })
 
+(define_predicate "regio_operand"
+  (match_code "subreg,reg")
+{
+  if (register_operand (op, mode))
+    {
+      int regno;
+
+      if (REG_P (op))
+	regno = REGNO (op);
+      else if (GET_CODE (op) == SUBREG && REG_P (SUBREG_REG (op)))
+	regno = REGNO (SUBREG_REG (op));
+      else
+	return 0;
+
+      return REGNO_REG_CLASS (regno) == REGIO_REGS;
+    }
+  return 0;
+})
+
 (define_predicate "reg_or_const_int_operand"
   (ior (match_operand 0 "const_int_operand")
        (match_operand 0 "register_operand")))
diff --git a/gcc/config/pru/pru-pragma.c b/gcc/config/pru/pru-pragma.c
index 01d076101f1..3beec236be1 100644
--- a/gcc/config/pru/pru-pragma.c
+++ b/gcc/config/pru/pru-pragma.c
@@ -83,4 +83,6 @@  pru_register_pragmas (void)
 {
   c_register_pragma (NULL, "ctable_entry", pru_pragma_ctable_entry);
   c_register_pragma (NULL, "CTABLE_ENTRY", pru_pragma_ctable_entry);
+
+  c_register_addr_space ("__regio_symbol", ADDR_SPACE_REGIO);
 }
diff --git a/gcc/config/pru/pru-protos.h b/gcc/config/pru/pru-protos.h
index 74129e9b9ed..031ea9e2fab 100644
--- a/gcc/config/pru/pru-protos.h
+++ b/gcc/config/pru/pru-protos.h
@@ -62,7 +62,10 @@  extern int pru_get_ctable_exact_base_index (unsigned HOST_WIDE_INT caddr);
 extern int pru_get_ctable_base_index (unsigned HOST_WIDE_INT caddr);
 extern int pru_get_ctable_base_offset (unsigned HOST_WIDE_INT caddr);
 
+extern int pru_symref2ioregno (rtx op);
+
 extern void pru_register_abicheck_pass (void);
+
 #endif /* RTX_CODE */
 
 #ifdef TREE_CODE
diff --git a/gcc/config/pru/pru.c b/gcc/config/pru/pru.c
index 30d0da194ce..9f264b4698d 100644
--- a/gcc/config/pru/pru.c
+++ b/gcc/config/pru/pru.c
@@ -1403,11 +1403,42 @@  pru_valid_addr_expr_p (machine_mode mode, rtx base, rtx offset, bool strict_p)
     return false;
 }
 
-/* Implement TARGET_LEGITIMATE_ADDRESS_P.  */
+/* Return register number (either for r30 or r31) which maps to the
+   corresponding symbol OP's name in the __regio_symbol address namespace.
+
+   If no mapping can be established (i.e. symbol name is invalid), then
+   return -1.  */
+int pru_symref2ioregno (rtx op)
+{
+  if (!SYMBOL_REF_P (op))
+    return -1;
+
+  const char *name = XSTR (op, 0);
+  if (!strcmp (name, "__R30"))
+    return R30_REGNUM;
+  else if (!strcmp (name, "__R31"))
+    return R31_REGNUM;
+  else
+    return -1;
+}
+
+/* Implement TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P.  */
 static bool
-pru_legitimate_address_p (machine_mode mode,
-			    rtx operand, bool strict_p)
+pru_addr_space_legitimate_address_p (machine_mode mode, rtx operand,
+				     bool strict_p, addr_space_t as)
 {
+  if (as == ADDR_SPACE_REGIO)
+    {
+      /*  Address space constraints for __regio_symbol have been checked in
+	  TARGET_INSERT_ATTRIBUTES, and some more checks will be done
+	  during RTL expansion of "mov<mode>".  */
+      return true;
+    }
+  else if (as != ADDR_SPACE_GENERIC)
+    {
+      gcc_unreachable ();
+    }
+
   switch (GET_CODE (operand))
     {
     /* Direct.  */
@@ -2002,6 +2033,117 @@  pru_file_start (void)
      need to confuse users with this warning.  */
   fprintf (asm_out_file, "\t.set no_warn_regname_label\n");
 }
+
+/* Scan type TYP for pointer references to address space other than
+   ADDR_SPACE_GENERIC.  Return true if such reference is found.
+   Much of this code was taken from the avr port.  */
+
+static bool
+pru_nongeneric_pointer_addrspace (tree typ)
+{
+  while (ARRAY_TYPE == TREE_CODE (typ))
+    typ = TREE_TYPE (typ);
+
+  if (POINTER_TYPE_P (typ))
+    {
+      addr_space_t as;
+      tree target = TREE_TYPE (typ);
+
+      /* Pointer to function: Test the function's return type.  */
+      if (FUNCTION_TYPE == TREE_CODE (target))
+	return pru_nongeneric_pointer_addrspace (TREE_TYPE (target));
+
+      /* "Ordinary" pointers... */
+
+      while (TREE_CODE (target) == ARRAY_TYPE)
+	target = TREE_TYPE (target);
+
+      as = TYPE_ADDR_SPACE (target);
+
+      if (!ADDR_SPACE_GENERIC_P (as))
+	return true;
+
+      /* Scan pointer's target type.  */
+      return pru_nongeneric_pointer_addrspace (target);
+    }
+
+  return false;
+}
+
+/* Implement `TARGET_INSERT_ATTRIBUTES'.  For PRU it's used as a hook to
+   provide better diagnostics for some invalid usages of the __regio_symbol
+   address space.
+
+   Any escapes of the following checks are supposed to be caught
+   during the "mov<mode>" pattern expansion.  */
+
+static void
+pru_insert_attributes (tree node, tree *attributes ATTRIBUTE_UNUSED)
+{
+
+  /* Validate __regio_symbol variable declarations.  */
+  if (VAR_P (node))
+    {
+      const char *name = DECL_NAME (node)
+			  ? IDENTIFIER_POINTER (DECL_NAME (node))
+			  : "<unknown>";
+      tree typ = TREE_TYPE (node);
+      addr_space_t as = TYPE_ADDR_SPACE (typ);
+
+      if (as == ADDR_SPACE_GENERIC)
+	return;
+
+      if (AGGREGATE_TYPE_P (typ))
+	{
+	  error ("aggregate types are prohibited in "
+		 "%<__regio_symbol%> address space");
+	  /* Don't bother anymore.  Below checks would pile
+	     meaningless errors, which would confuse user.  */
+	  return;
+	}
+      if (DECL_INITIAL (node) != NULL_TREE)
+	error ("variables in %<__regio_symbol%> address space "
+	       "cannot have initial value");
+      if (DECL_REGISTER (node))
+	error ("variables in %<__regio_symbol%> address space "
+	       "cannot be declared %<register%>");
+      if (!TYPE_VOLATILE (typ))
+	error ("variables in %<__regio_symbol%> address space "
+	       "must be declared %<volatile%>");
+      if (!DECL_EXTERNAL (node))
+	error ("variables in %<__regio_symbol%> address space "
+	       "must be declared %<extern%>");
+      if (TYPE_MODE (typ) != SImode)
+	error ("only 32-bit access is supported "
+	       "for %<__regio_symbol%> address space");
+      if (strcmp (name, "__R30") != 0 && strcmp (name, "__R31") != 0)
+	error ("register name %<%s%> not recognized "
+	       "in %<__regio_symbol%> address space", name);
+    }
+
+  tree typ = NULL_TREE;
+
+  switch (TREE_CODE (node))
+    {
+    case FUNCTION_DECL:
+      typ = TREE_TYPE (TREE_TYPE (node));
+      break;
+    case TYPE_DECL:
+    case RESULT_DECL:
+    case VAR_DECL:
+    case FIELD_DECL:
+    case PARM_DECL:
+      typ = TREE_TYPE (node);
+      break;
+    case POINTER_TYPE:
+      typ = node;
+      break;
+    default:
+      break;
+    }
+  if (typ != NULL_TREE && pru_nongeneric_pointer_addrspace (typ))
+    error ("pointers to %<__regio_symbol%> address space are prohibited");
+}
 
 /* Function argument related.  */
 
@@ -2933,6 +3075,9 @@  pru_unwind_word_mode (void)
 #undef TARGET_ASM_FILE_START
 #define TARGET_ASM_FILE_START pru_file_start
 
+#undef  TARGET_INSERT_ATTRIBUTES
+#define TARGET_INSERT_ATTRIBUTES pru_insert_attributes
+
 #undef TARGET_INIT_BUILTINS
 #define TARGET_INIT_BUILTINS pru_init_builtins
 #undef TARGET_EXPAND_BUILTIN
@@ -2979,8 +3124,9 @@  pru_unwind_word_mode (void)
 #undef TARGET_MUST_PASS_IN_STACK
 #define TARGET_MUST_PASS_IN_STACK must_pass_in_stack_var_size
 
-#undef TARGET_LEGITIMATE_ADDRESS_P
-#define TARGET_LEGITIMATE_ADDRESS_P pru_legitimate_address_p
+#undef TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P
+#define TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P \
+  pru_addr_space_legitimate_address_p
 
 #undef TARGET_INIT_LIBFUNCS
 #define TARGET_INIT_LIBFUNCS pru_init_libfuncs
diff --git a/gcc/config/pru/pru.h b/gcc/config/pru/pru.h
index 9b6be323e6d..03f08b1720f 100644
--- a/gcc/config/pru/pru.h
+++ b/gcc/config/pru/pru.h
@@ -215,6 +215,7 @@  enum reg_class
   MULDST_REGS,
   MULSRC0_REGS,
   MULSRC1_REGS,
+  REGIO_REGS,
   GP_REGS,
   ALL_REGS,
   LIM_REG_CLASSES
@@ -229,6 +230,7 @@  enum reg_class
      "MULDST_REGS",	  \
      "MULSRC0_REGS",	  \
      "MULSRC1_REGS",	  \
+     "REGIO_REGS",	  \
      "GP_REGS",		  \
      "ALL_REGS" }
 
@@ -242,6 +244,7 @@  enum reg_class
     /* MULDST_REGS    */ { 0, 0, 0, 0x00000f00, 0},		\
     /* MULSRC0_REGS   */ { 0, 0, 0, 0x000f0000, 0},		\
     /* MULSRC1_REGS   */ { 0, 0, 0, 0x00f00000, 0},		\
+    /* REGIO_REGS     */ { 0, 0, 0, 0xff000000, 0},		\
     /* GP_REGS	      */ { ~0, ~0, ~0, ~0, 0},			\
     /* ALL_REGS	      */ { ~0,~0, ~0, ~0, ~0}			\
   }
@@ -252,6 +255,8 @@  enum reg_class
 	((REGNO) == MULDST_REGNUM ? MULDST_REGS				    \
 	 : (REGNO) == MULSRC0_REGNUM ? MULSRC0_REGS			    \
 	 : (REGNO) == MULSRC1_REGNUM ? MULSRC1_REGS			    \
+	 : (REGNO) == R30_REGNUM ? REGIO_REGS				    \
+	 : (REGNO) == R31_REGNUM ? REGIO_REGS				    \
 	 : (REGNO) >= FIRST_ARG_REGNUM					    \
 	    && (REGNO) <= LAST_ARG_REGNUM ? SIB_REGS			    \
 	 : (REGNO) == STATIC_CHAIN_REGNUM ? SIB_REGS			    \
diff --git a/gcc/config/pru/pru.md b/gcc/config/pru/pru.md
index e6cfa8ec3bf..c0ded8ea4e5 100644
--- a/gcc/config/pru/pru.md
+++ b/gcc/config/pru/pru.md
@@ -36,6 +36,8 @@  (define_constants
    (MULSRC0_REGNUM		112) ; Multiply source register.
    (MULSRC1_REGNUM		116) ; Multiply source register.
    (LAST_NONIO_GP_REGNUM	119) ; Last non-I/O general purpose register.
+   (R30_REGNUM			120) ; R30 I/O register.
+   (R31_REGNUM			124) ; R31 I/O register.
    (LOOPCNTR_REGNUM		128) ; internal LOOP counter register
    (LAST_GP_REGNUM		132) ; Last general purpose register.
 
@@ -49,6 +51,13 @@  (define_constants
   ]
 )
 
+;; Enumerate address spaces.
+(define_constants
+  [
+   (ADDR_SPACE_REGIO		1) ; Access to R30 and R31 I/O registers.
+  ]
+)
+
 ;; Enumeration of UNSPECs.
 
 (define_c_enum "unspec" [
@@ -68,6 +77,9 @@  (define_c_enum "unspecv" [
   UNSPECV_HALT
 
   UNSPECV_BLOCKAGE
+
+  UNSPECV_REGIO_READ
+  UNSPECV_REGIO_WRITE
 ])
 
 ; Length of an instruction (in bytes).
@@ -129,11 +141,62 @@  (define_expand "mov<mode>"
 	(match_operand:MOV8_16_32 1 "general_operand"))]
   ""
 {
-  /* It helps to split constant loading and memory access
-     early, so that the LDI/LDI32 instructions can be hoisted
-     outside a loop body.  */
-  if (MEM_P (operands[0]))
-    operands[1] = force_reg (<MODE>mode, operands[1]);
+  if (MEM_P (operands[0])
+      && MEM_ADDR_SPACE (operands[0]) == ADDR_SPACE_REGIO)
+
+    {
+      /* Intercept writes to the SImode register I/O "address space".  */
+      gcc_assert (<MODE>mode == SImode);
+
+      if (!SYMBOL_REF_P (XEXP (operands[0], 0)))
+	{
+	  error ("invalid access to %<__regio_symbol%> address space");
+	  FAIL;
+	}
+
+      if (!REG_P (operands[1]))
+	operands[1] = force_reg (<MODE>mode, operands[1]);
+
+      int regiono = pru_symref2ioregno (XEXP (operands[0], 0));
+      gcc_assert (regiono >= 0);
+      rtx regio = gen_rtx_REG (<MODE>mode, regiono);
+      rtx unspecv = gen_rtx_UNSPEC_VOLATILE (<MODE>mode,
+					     gen_rtvec (1, operands[1]),
+					     UNSPECV_REGIO_WRITE);
+      emit_insn (gen_rtx_SET (regio, unspecv));
+      DONE;
+    }
+  else if (MEM_P (operands[1])
+	   && MEM_ADDR_SPACE (operands[1]) == ADDR_SPACE_REGIO)
+    {
+      /* Intercept reads from the SImode register I/O "address space".  */
+      gcc_assert (<MODE>mode == SImode);
+
+      if (!SYMBOL_REF_P (XEXP (operands[1], 0)))
+	{
+	  error ("invalid access to %<__regio_symbol%> address space");
+	  FAIL;
+	}
+
+      if (MEM_P (operands[0]))
+	operands[0] = force_reg (<MODE>mode, operands[0]);
+
+      int regiono = pru_symref2ioregno (XEXP (operands[1], 0));
+      gcc_assert (regiono >= 0);
+      rtx regio = gen_rtx_REG (<MODE>mode, regiono);
+      rtx unspecv = gen_rtx_UNSPEC_VOLATILE (<MODE>mode,
+					     gen_rtvec (1, regio),
+					     UNSPECV_REGIO_READ);
+      emit_insn (gen_rtx_SET (operands[0], unspecv));
+      DONE;
+    }
+  else if (MEM_P (operands[0]))
+    {
+    /* It helps to split constant loading and memory access
+       early, so that the LDI/LDI32 instructions can be hoisted
+       outside a loop body.  */
+      operands[1] = force_reg (<MODE>mode, operands[1]);
+    }
 })
 
 ;; Keep a single pattern for 32 bit MOV operations.  LRA requires that the
@@ -546,6 +609,35 @@  (define_insn "ashr<mode>3_single"
 
 (include "alu-zext.md")
 
+;; Patterns for accessing the R30/R31 I/O registers.
+
+(define_insn "*regio_readsi"
+  [(set (match_operand:SI 0 "register_operand" "=r")
+    (unspec_volatile:SI
+      [(match_operand:SI 1 "regio_operand" "Rrio")]
+      UNSPECV_REGIO_READ))]
+  ""
+  "mov\\t%0, %1"
+  [(set_attr "type"     "alu")])
+
+(define_insn "*regio_nozext_writesi"
+  [(set (match_operand:SI 0 "regio_operand" "=Rrio")
+    (unspec_volatile:SI
+      [(match_operand:SI 1 "register_operand" "r")]
+      UNSPECV_REGIO_WRITE))]
+  ""
+  "mov\\t%0, %1"
+  [(set_attr "type"     "alu")])
+
+(define_insn "*regio_zext_write_r30<EQS0:mode>"
+  [(set (match_operand:SI 0 "regio_operand" "=Rrio")
+    (unspec_volatile:SI
+      [(zero_extend:SI (match_operand:EQS0 1 "register_operand" "r"))]
+      UNSPECV_REGIO_WRITE))]
+  ""
+  "mov\\t%0, %1"
+  [(set_attr "type"     "alu")])
+
 ;; DI logical ops could be automatically split into WORD-mode ops in
 ;; expand_binop().  But then we'll miss an opportunity to use SI mode
 ;; operations, since WORD mode for PRU is QI.
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 9501a60f20e..63be63f091a 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -1406,7 +1406,7 @@  As an extension, GNU C supports named address spaces as
 defined in the N1275 draft of ISO/IEC DTR 18037.  Support for named
 address spaces in GCC will evolve as the draft technical report
 changes.  Calling conventions for any target might also change.  At
-present, only the AVR, M32C, RL78, and x86 targets support
+present, only the AVR, M32C, PRU, RL78, and x86 targets support
 address spaces other than the generic address space.
 
 Address space identifiers may be used exactly like any other C type
@@ -1586,6 +1586,23 @@  order to access memory beyond the first 64@tie{}Ki bytes.  If
 @code{__far} is used with the M32CM or M32C CPU variants, it has no
 effect.
 
+@subsection PRU Named Address Spaces
+@cindex @code{__regio_symbol} PRU Named Address Spaces
+
+On the PRU target, variables qualified with @code{__regio_symbol} are
+aliases used to access the special I/O CPU registers.  They must be
+declared as @code{extern} because such variables will not be allocated in
+any data memory.  They must also be marked as @code{volatile}, and can
+only be 32-bit integer types.  The only names those variables can have
+are @code{__R30} and @code{__R31}, representing respectively the
+@code{R30} and @code{R31} special I/O CPU registers.  Hence the following
+example is the only valid usage of @code{__regio_symbol}:
+
+@smallexample
+extern volatile __regio_symbol uint32_t __R30;
+extern volatile __regio_symbol uint32_t __R31;
+@end smallexample
+
 @subsection RL78 Named Address Spaces
 @cindex @code{__far} RL78 Named Address Spaces
 
diff --git a/gcc/testsuite/gcc.target/pru/regio-as-pointer-2.c b/gcc/testsuite/gcc.target/pru/regio-as-pointer-2.c
new file mode 100644
index 00000000000..06d9473e995
--- /dev/null
+++ b/gcc/testsuite/gcc.target/pru/regio-as-pointer-2.c
@@ -0,0 +1,11 @@ 
+/* Test __regio_symbol invalid attempt to get regio variable address.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O0" } */
+
+#include "regio.h"
+
+uint32_t test(void)
+{
+  return *(&__R30+1); /* { dg-error "invalid access to '__regio_symbol' address space" } */
+}
diff --git a/gcc/testsuite/gcc.target/pru/regio-as-pointer.c b/gcc/testsuite/gcc.target/pru/regio-as-pointer.c
new file mode 100644
index 00000000000..885464f498d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/pru/regio-as-pointer.c
@@ -0,0 +1,11 @@ 
+/* Test __regio_symbol invalid attempt to get regio variable address.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O0" } */
+
+#include "regio.h"
+
+uint32_t *test(void)
+{
+  return &__R31; /* { dg-error "return from pointer to non-enclosed address space" } */
+}
diff --git a/gcc/testsuite/gcc.target/pru/regio-decl-2.c b/gcc/testsuite/gcc.target/pru/regio-decl-2.c
new file mode 100644
index 00000000000..9a9338e4b42
--- /dev/null
+++ b/gcc/testsuite/gcc.target/pru/regio-decl-2.c
@@ -0,0 +1,13 @@ 
+/* Test __regio_symbol diagnostics for unsupported declarations.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O1" } */
+
+#include <stdint.h>
+
+extern volatile __regio_symbol
+uint32_t __R30[10]; /* { dg-error "aggregate types are prohibited in '__regio_symbol' address space" } */
+
+/* { dg-warning "'__R31' initialized and declared 'extern'" "" { target *-*-* } 0 } */
+extern volatile __regio_symbol
+uint32_t __R31 = 2; /* { dg-error "variables in '__regio_symbol' address space cannot have initial value" } */
diff --git a/gcc/testsuite/gcc.target/pru/regio-decl-3.c b/gcc/testsuite/gcc.target/pru/regio-decl-3.c
new file mode 100644
index 00000000000..36fcd8ac730
--- /dev/null
+++ b/gcc/testsuite/gcc.target/pru/regio-decl-3.c
@@ -0,0 +1,19 @@ 
+/* Test __regio_symbol diagnostics for unsupported declarations.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O1" } */
+
+#include <stdint.h>
+
+uint32_t __regio_symbol *test1(void); /* { dg-error "pointers to '__regio_symbol' address space are prohibited" } */
+
+void test2(uint32_t __regio_symbol __R30); /* { dg-error "'__regio_symbol' specified for parameter '__R30'" } */
+
+void test3(uint32_t __regio_symbol *__R30); /* { dg-error "pointers to '__regio_symbol' address space are prohibited" } */
+
+typedef volatile uint32_t __regio_symbol * regio_type1_t; /* { dg-error "pointers to '__regio_symbol' address space are prohibited" } */
+
+struct A {
+  uint32_t __regio_symbol *__R30; /* { dg-error "pointers to '__regio_symbol' address space are prohibited" } */
+  uint32_t __regio_symbol __R31; /* { dg-error "__regio_symbol' specified for structure field '__R31'" } */
+};
diff --git a/gcc/testsuite/gcc.target/pru/regio-decl-4.c b/gcc/testsuite/gcc.target/pru/regio-decl-4.c
new file mode 100644
index 00000000000..48c45a7c918
--- /dev/null
+++ b/gcc/testsuite/gcc.target/pru/regio-decl-4.c
@@ -0,0 +1,17 @@ 
+/* Test __regio_symbol diagnostics for unsupported access.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O1" } */
+
+#include <stdint.h>
+
+extern volatile uint32_t __regio_symbol *__R30;
+uint32_t test_r(void)
+{
+  return *__R30; /* { dg-error "invalid access to '__regio_symbol' address space" } */
+}
+
+void test_w(uint32_t a)
+{
+  *__R30 = a; /* { dg-error "invalid access to '__regio_symbol' address space" } */
+}
diff --git a/gcc/testsuite/gcc.target/pru/regio-decl.c b/gcc/testsuite/gcc.target/pru/regio-decl.c
new file mode 100644
index 00000000000..a4962aa4495
--- /dev/null
+++ b/gcc/testsuite/gcc.target/pru/regio-decl.c
@@ -0,0 +1,15 @@ 
+/* Test __regio_symbol diagnostics for unsupported declarations.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O1" } */
+
+#include <stdint.h>
+
+volatile __regio_symbol
+uint32_t __R30; /* { dg-error "variables in '__regio_symbol' address space must be declared 'extern'" } */
+
+extern __regio_symbol
+uint32_t __R31; /* { dg-error "variables in '__regio_symbol' address space must be declared 'volatile'" } */
+
+extern volatile
+__regio_symbol uint32_t __R32; /* { dg-error "register name '__R32' not recognized in '__regio_symbol' address space" } */
diff --git a/gcc/testsuite/gcc.target/pru/regio-di.c b/gcc/testsuite/gcc.target/pru/regio-di.c
new file mode 100644
index 00000000000..a4226274fc1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/pru/regio-di.c
@@ -0,0 +1,9 @@ 
+/* Test __regio_symbol invalid access diagnostic for DImode.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O1" } */
+
+#include <stdint.h>
+
+extern volatile
+__regio_symbol uint64_t __R31; /* { dg-error "only 32-bit access is supported for '__regio_symbol' address space" } */
diff --git a/gcc/testsuite/gcc.target/pru/regio-hi.c b/gcc/testsuite/gcc.target/pru/regio-hi.c
new file mode 100644
index 00000000000..5b89e8cea96
--- /dev/null
+++ b/gcc/testsuite/gcc.target/pru/regio-hi.c
@@ -0,0 +1,9 @@ 
+/* Test __regio_symbol invalid access diagnostic for HImode.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O1" } */
+
+#include <stdint.h>
+
+extern volatile __regio_symbol
+uint16_t __R31; /* { dg-error "only 32-bit access is supported for '__regio_symbol' address space" } */
diff --git a/gcc/testsuite/gcc.target/pru/regio-qi.c b/gcc/testsuite/gcc.target/pru/regio-qi.c
new file mode 100644
index 00000000000..a3f63062b06
--- /dev/null
+++ b/gcc/testsuite/gcc.target/pru/regio-qi.c
@@ -0,0 +1,9 @@ 
+/* Test __regio_symbol invalid access diagnostic for QImode.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O1" } */
+
+#include <stdint.h>
+
+extern volatile __regio_symbol
+uint8_t __R31; /* { dg-error "only 32-bit access is supported for '__regio_symbol' address space" } */
diff --git a/gcc/testsuite/gcc.target/pru/regio.c b/gcc/testsuite/gcc.target/pru/regio.c
new file mode 100644
index 00000000000..2f01263b902
--- /dev/null
+++ b/gcc/testsuite/gcc.target/pru/regio.c
@@ -0,0 +1,58 @@ 
+/* __regio_symbol operations. */
+
+/* { dg-do compile } */
+/* { dg-options "-Os" } */
+
+#include "regio.h"
+
+void
+test_r30_w_const (void)
+{
+  /* { dg-final { scan-assembler "mov\\tr30, r\[012\]\[0-9\]?" } } */
+  __R30 = 1;
+}
+
+void
+test_r31_w_zext_qi (unsigned char val1)
+{
+  /* { dg-final { scan-assembler "mov\\tr31, r14.b0" } } */
+  __R31 = val1;
+}
+
+void
+test_r31_w_zext_hi (unsigned short val1)
+{
+  /* { dg-final { scan-assembler "mov\\tr31, r14.w0" } } */
+  __R31 = val1;
+}
+
+void
+test_r31_w (unsigned int val1)
+{
+  /* { dg-final { scan-assembler "mov\\tr31, r14" } } */
+  __R31 = val1;
+}
+
+uint32_t
+test_r30_r (void)
+{
+  /* { dg-final { scan-assembler "mov\\tr14, r30" } } */
+  return __R30;
+}
+
+void
+test_r30_rw (void)
+{
+  /* { dg-final { scan-assembler "mov\\tr\[012\]\[0-9\]?, r30" } } */
+  /* { dg-final { scan-assembler "mov\\tr30, r\[012\]\[0-9\]?" } } */
+  __R30 = __R30;
+}
+
+void
+test_r31_rw (void)
+{
+  /* { dg-final { scan-assembler "mov\\tr\[012\]\[0-9\]?, r31" } } */
+  /* { dg-final { scan-assembler "mov\\tr31, r\[012\]\[0-9\]?" } } */
+  __R31 |= 101;
+}
+
diff --git a/gcc/testsuite/gcc.target/pru/regio.h b/gcc/testsuite/gcc.target/pru/regio.h
new file mode 100644
index 00000000000..3a120c1d2d1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/pru/regio.h
@@ -0,0 +1,7 @@ 
+
+#include <stdint.h>
+
+/* Declare the I/O registers.  */
+extern volatile __regio_symbol uint32_t __R30;
+extern volatile __regio_symbol uint32_t __R31;
+