constraints.md ("S"): Match r0rel_constant_p too.

2017-10-26  Sandra Loosemore  <sandra@codesourcery.com>

	gcc/
	* config/nios2/constraints.md ("S"): Match r0rel_constant_p too.
	* config/nios2/nios2-protos.h (r0rel_constant_p): Declare.
	* config/nios2/nios2.c: (nios2_r0rel_sec_regex): New.
	(nios2_option_overide): Initialize it.  Don't allow R0-relative 
	addressing with PIC.
	(nios2_rtx_costs): Handle r0rel_constant_p like gprel_constant_p.
	(nios2_symbolic_constant_p): Likewise.
	(nios2_legitimate_address_p): Likewise.
	(nios2_r0rel_section_name_p): New.
	(nios2_symbol_ref_in_r0rel_data_p): New.
	(nios2_emit_move_sequence): Handle r0rel_constant_p.
	(r0rel_constant_p): New.
	(nios2_print_operand_address): Handle r0rel_constant_p.
	(nios2_cdx_narrow_form_p): Likewise.
	* config/nios2/nios2.opt (mr0rel-sec=): New option.
	* doc/invoke.texi (Option Summary): Add -mr0rel-sec.
	(Nios II Options): Document -mr0rel-sec.

	gcc/testsuite/
	* gcc.target/nios2/gpopt-r0rel-sec.c: New.

From-SVN: r254124

4 files changed, 88 insertions, 17 deletions

diff --git a/gcc/config/nios2/constraints.md b/gcc/config/nios2/constraints.md
index c6c53926..51f71cf 100644
--- a/gcc/config/nios2/constraints.md
+++ b/gcc/config/nios2/constraints.md
@@ -95,8 +95,8 @@
        (match_test "TARGET_ARCH_R2 && ANDCLEAR_INT (ival)")))
 
 (define_constraint "S"
-  "An immediate stored in small data, accessible by GP."
-  (match_test "gprel_constant_p (op)"))
+  "An immediate stored in small data, accessible by GP, or by offset from r0."
+  (match_test "gprel_constant_p (op) || r0rel_constant_p (op)"))
 
 (define_constraint "T"
   "A constant unspec offset representing a relocation."
diff --git a/gcc/config/nios2/nios2-protos.h b/gcc/config/nios2/nios2-protos.h
index 6df65bb..84d450b 100644
--- a/gcc/config/nios2/nios2-protos.h
+++ b/gcc/config/nios2/nios2-protos.h
@@ -52,6 +52,7 @@ extern const char * nios2_add_insn_asm (rtx_insn *, rtx *);
 
 extern bool nios2_legitimate_pic_operand_p (rtx);
 extern bool gprel_constant_p (rtx);
+extern bool r0rel_constant_p (rtx);
 extern bool nios2_regno_ok_for_base_p (int, bool);
 extern bool nios2_unspec_reloc_p (rtx);
 
diff --git a/gcc/config/nios2/nios2.c b/gcc/config/nios2/nios2.c
index 3aade7b..cdd5e9a 100644
--- a/gcc/config/nios2/nios2.c
+++ b/gcc/config/nios2/nios2.c
@@ -106,6 +106,7 @@ static bool custom_code_conflict = false;
 
 /* State for command-line options.  */
 regex_t nios2_gprel_sec_regex;
+regex_t nios2_r0rel_sec_regex;
 
 
 /* Definition of builtin function types for nios2.  */
@@ -1375,22 +1376,30 @@ nios2_option_override (void)
 	nios2_gpopt_option = gpopt_local;
     }
 
-  /* GP-relative addressing doesn't make sense for PIC.  */
+  /* GP-relative and r0-relative addressing don't make sense for PIC.  */
   if (flag_pic)
-    { 
+    {
       if (nios2_gpopt_option != gpopt_none)
-        error ("-mgpopt not supported with PIC.");
+	error ("-mgpopt not supported with PIC.");
       if (nios2_gprel_sec)
-        error ("-mgprel-sec= not supported with PIC.");
+	error ("-mgprel-sec= not supported with PIC.");
+      if (nios2_r0rel_sec)
+	error ("-mr0rel-sec= not supported with PIC.");
     }
 
-  /* Process -mgprel-sec=.  */
+  /* Process -mgprel-sec= and -m0rel-sec=.  */
   if (nios2_gprel_sec)
     {
       if (regcomp (&nios2_gprel_sec_regex, nios2_gprel_sec, 
 		   REG_EXTENDED | REG_NOSUB))
 	error ("-mgprel-sec= argument is not a valid regular expression.");
     }
+  if (nios2_r0rel_sec)
+    {
+      if (regcomp (&nios2_r0rel_sec_regex, nios2_r0rel_sec, 
+		   REG_EXTENDED | REG_NOSUB))
+	error ("-mr0rel-sec= argument is not a valid regular expression.");
+    }
 
   /* If we don't have mul, we don't have mulx either!  */
   if (!TARGET_HAS_MUL && TARGET_HAS_MULX)
@@ -1478,7 +1487,7 @@ nios2_rtx_costs (rtx x, machine_mode mode,
       case SYMBOL_REF:
       case CONST:
       case CONST_DOUBLE:
-	if (gprel_constant_p (x))
+	if (gprel_constant_p (x) || r0rel_constant_p (x))
           {
             *total = COSTS_N_INSNS (1);
             return true;
@@ -2028,6 +2037,7 @@ nios2_symbolic_constant_p (rtx x)
       return (SYMBOL_REF_P (base)
 		&& !SYMBOL_REF_TLS_MODEL (base)
 		&& !gprel_constant_p (base)
+		&& !r0rel_constant_p (base)
 		&& SMALL_INT (INTVAL (offset)));
     }
   return false;
@@ -2129,7 +2139,7 @@ nios2_legitimate_address_p (machine_mode mode ATTRIBUTE_UNUSED,
 
       /* Else, fall through.  */
     case CONST:
-      if (gprel_constant_p (operand))
+      if (gprel_constant_p (operand) || r0rel_constant_p (operand))
 	return true;
 
       /* Else, fall through.  */
@@ -2294,6 +2304,14 @@ nios2_small_section_name_p (const char *section)
 	      && regexec (&nios2_gprel_sec_regex, section, 0, NULL, 0) == 0));
 }
 
+/* Return true if SECTION is a r0-relative section name.  */
+static bool
+nios2_r0rel_section_name_p (const char *section)
+{
+  return (nios2_r0rel_sec 
+	  && regexec (&nios2_r0rel_sec_regex, section, 0, NULL, 0) == 0);
+}
+
 /* Return true if EXP should be placed in the small data section.  */
 static bool
 nios2_in_small_data_p (const_tree exp)
@@ -2400,6 +2418,33 @@ nios2_symbol_ref_in_small_data_p (rtx sym)
     }
 }
 
+/* Likewise for r0-relative addressing.  */
+static bool
+nios2_symbol_ref_in_r0rel_data_p (rtx sym)
+{
+  tree decl;
+
+  gcc_assert (GET_CODE (sym) == SYMBOL_REF);
+  decl = SYMBOL_REF_DECL (sym);
+
+  /* TLS variables are not accessed through r0.  */
+  if (SYMBOL_REF_TLS_MODEL (sym) != 0)
+    return false;
+
+  /* On Nios II R2, there is no r0-relative relocation that can be
+     used with "io" instructions.  So, if we are implicitly generating
+     those instructions, we cannot emit r0-relative accesses.  */
+  if (TARGET_ARCH_R2
+      && (TARGET_BYPASS_CACHE || TARGET_BYPASS_CACHE_VOLATILE))
+    return false;
+
+  /* If the user has explicitly placed the symbol in a r0rel section
+     via an attribute, generate r0-relative addressing.  */
+  if (decl && DECL_SECTION_NAME (decl))
+    return nios2_r0rel_section_name_p (DECL_SECTION_NAME (decl));
+  return false;
+}
+
 /* Implement TARGET_SECTION_TYPE_FLAGS.  */
 
 static unsigned int
@@ -2633,8 +2678,9 @@ nios2_emit_move_sequence (rtx *operands, machine_mode mode)
 	      return true;
 	    }
 	}
-      else if (gprel_constant_p (from))
-	/* Handled directly by movsi_internal as gp + offset.  */
+      else if (gprel_constant_p (from) || r0rel_constant_p (from))
+	/* Handled directly by movsi_internal as gp + offset 
+	   or r0 + offset.  */
 	;
       else if (nios2_large_constant_p (from))
 	/* This case covers either a regular symbol reference or an UNSPEC
@@ -2984,6 +3030,20 @@ gprel_constant_p (rtx op)
   return false;
 }
 
+/* Likewise if this is a zero-relative accessible reference.  */
+bool
+r0rel_constant_p (rtx op)
+{
+  if (GET_CODE (op) == SYMBOL_REF
+      && nios2_symbol_ref_in_r0rel_data_p (op))
+    return true;
+  else if (GET_CODE (op) == CONST
+           && GET_CODE (XEXP (op, 0)) == PLUS)
+    return r0rel_constant_p (XEXP (XEXP (op, 0), 0));
+
+  return false;
+}
+
 /* Return the name string for a supported unspec reloc offset.  */
 static const char *
 nios2_unspec_reloc_name (int unspec)
@@ -3048,7 +3108,13 @@ nios2_print_operand_address (FILE *file, machine_mode mode, rtx op)
           fprintf (file, ")(%s)", reg_names[GP_REGNO]);
           return;
         }
-
+      else if (r0rel_constant_p (op))
+        {
+          fprintf (file, "%%lo(");
+          output_addr_const (file, op);
+          fprintf (file, ")(r0)");
+          return;
+        }
       break;
 
     case PLUS:
@@ -4654,8 +4720,8 @@ nios2_cdx_narrow_form_p (rtx_insn *insn)
 		|| TARGET_BYPASS_CACHE)
 	      return false;
 	    addr = XEXP (mem, 0);
-	    /* GP-based references are never narrow.  */
-	    if (gprel_constant_p (addr))
+	    /* GP-based and R0-based references are never narrow.  */
+	    if (gprel_constant_p (addr) || r0rel_constant_p (addr))
 		return false;
 	    /* %lo requires a 16-bit relocation and is never narrow.  */
 	    if (GET_CODE (addr) == LO_SUM)
@@ -4701,8 +4767,8 @@ nios2_cdx_narrow_form_p (rtx_insn *insn)
 	      || TARGET_BYPASS_CACHE)
 	    return false;
 	  addr = XEXP (mem, 0);
-	  /* GP-based references are never narrow.  */
-	  if (gprel_constant_p (addr))
+	  /* GP-based and r0-based references are never narrow.  */
+	  if (gprel_constant_p (addr) || r0rel_constant_p (addr))
 	    return false;
 	  /* %lo requires a 16-bit relocation and is never narrow.  */
 	  if (GET_CODE (addr) == LO_SUM)
diff --git a/gcc/config/nios2/nios2.opt b/gcc/config/nios2/nios2.opt
index d08405e..a50dbee 100644
--- a/gcc/config/nios2/nios2.opt
+++ b/gcc/config/nios2/nios2.opt
@@ -589,4 +589,8 @@ Enable generation of R2 CDX instructions.
 
 mgprel-sec=
 Target RejectNegative Joined Var(nios2_gprel_sec) Init(NULL)
-Regular expression matching additional GP-addressible small-data section names.
+Regular expression matching additional GP-addressible section names.
+
+mr0rel-sec=
+Target RejectNegative Joined Var(nios2_r0rel_sec) Init(NULL)
+Regular expression matching section names for r0-relative addressing.