From: Ian Lance Taylor <ian@gcc.gnu.org>
Date: Thu, 21 Apr 1994 18:28:09 +0000 (+0000)
Subject: Handle taking address of function when using -membedded-pic
X-Git-Tag: misc/cutover-egcs-0~6838
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=92544bdfd59b9deb0ae56887f89f6719321bc20e;p=thirdparty%2Fgcc.git

Handle taking address of function when using -membedded-pic

From-SVN: r7105
---

diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index 562a1e98a6d2..66c31e15a243 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -218,6 +218,11 @@ struct mips_frame_info zero_frame_info;
    for -mgpopt.  */
 static char *temp_filename;
 
+/* Pseudo-reg holding the address of the current function when
+   generating embedded PIC code.  Created by LEGITIMIZE_ADDRESS, used
+   by mips_finalize_pic if it was created.  */
+rtx embedded_pic_fnaddr_rtx;
+
 /* List of all MIPS punctuation characters used by print_operand.  */
 char mips_print_operand_punct[256];
 
@@ -853,6 +858,20 @@ mips_count_memory_refs (op, num)
 }
 
 
+/* Return RTL for the offset from the current function to the
+   argument.  */
+
+rtx
+embedded_pic_offset (x)
+     rtx x;
+{
+  if (embedded_pic_fnaddr_rtx == NULL)
+    embedded_pic_fnaddr_rtx = gen_reg_rtx (Pmode);
+  return gen_rtx (CONST, Pmode,
+		  gen_rtx (MINUS, Pmode, x,
+			   XEXP (DECL_RTL (current_function_decl), 0)));
+}
+
 /* Return the appropriate instructions to move one operand to another.  */
 
 char *
@@ -4199,6 +4218,33 @@ epilogue_reg_mentioned_p (insn)
   return 0;
 }
 
+
+/* When generating embedded PIC code we may need to get the address of
+   the current function.  We will need it if we take the address of
+   any symbol in the .text section.  */
+
+void
+mips_finalize_pic ()
+{
+  rtx seq;
+
+  if (! TARGET_EMBEDDED_PIC)
+    return;
+  if (embedded_pic_fnaddr_rtx == NULL)
+    return;
+
+  start_sequence ();
+
+  emit_insn (gen_get_fnaddr (embedded_pic_fnaddr_rtx,
+			     XEXP (DECL_RTL (current_function_decl), 0)));
+
+  seq = gen_sequence ();
+  end_sequence ();
+  emit_insn_after (seq, get_insns ());
+
+  embedded_pic_fnaddr_rtx = NULL;
+}
+
 
 /* Return the bytes needed to compute the frame pointer from the current
    stack pointer.
@@ -5221,7 +5267,17 @@ mips_select_section (decl, reloc)
 {
   int size = int_size_in_bytes (TREE_TYPE (decl));
 
-  if (TARGET_EMBEDDED_DATA)
+  if (TARGET_EMBEDDED_PIC
+      && TREE_CODE (decl) == STRING_CST
+      && !flag_writable_strings)
+    {
+      /* For embedded position independent code, put constant strings
+	 in the text section, because the data section is limited to
+	 64K in size.  */
+
+      text_section ();
+    }
+  else if (TARGET_EMBEDDED_DATA)
     {
       /* For embedded applications, always put an object in read-only data
 	 if possible, in order to reduce RAM usage.  */
diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
index dd4dc003649f..4f4b8f8ce1c9 100644
--- a/gcc/config/mips/mips.h
+++ b/gcc/config/mips/mips.h
@@ -132,6 +132,7 @@ extern struct rtx_def *mips_load_reg;	/* register to check for load delay */
 extern struct rtx_def *mips_load_reg2;	/* 2nd reg to check for load delay */
 extern struct rtx_def *mips_load_reg3;	/* 3rd reg to check for load delay */
 extern struct rtx_def *mips_load_reg4;	/* 4th reg to check for load delay */
+extern struct rtx_def *embedded_pic_fnaddr_rtx;	/* function address */
 
 /* Functions within mips.c that we reference.  */
 
@@ -183,6 +184,8 @@ extern int		simple_memory_operand ();
 extern int		small_int ();
 extern void		trace();
 extern int		uns_arith_operand ();
+extern struct rtx_def *	embedded_pic_offset ();
+extern void		mips_finalize_pic ();
 
 /* Recognition functions that return if a condition is true.  */
 extern int		address_operand ();
@@ -1292,6 +1295,7 @@ extern char mips_hard_regno_mode_ok[][FIRST_PSEUDO_REGISTER];
 
 #define PIC_FUNCTION_ADDR_REGNUM (GP_REG_FIRST + 25)
 
+#define FINALIZE_PIC mips_finalize_pic ()
 
 /* Define the classes of registers for register constraints in the
    machine description.  Also define ranges of constants.
@@ -2246,8 +2250,14 @@ typedef struct mips_args {
 	     appropriate relocation.  */				\
 									\
 	  /* Also accept CONST_INT addresses here, so no else.  */	\
+	  /* Reject combining an embedded PIC text segment reference	\
+	     with a register.  That requires an additional		\
+	     instruction.  */						\
 	  if (!TARGET_DEBUG_A_MODE					\
-	      && CONSTANT_ADDRESS_P (xplus1))				\
+	      && CONSTANT_ADDRESS_P (xplus1)				\
+	      && (!TARGET_EMBEDDED_PIC					\
+		  || code1 != CONST					\
+		  || GET_CODE (XEXP (xplus1, 0)) != MINUS))		\
 	    goto ADDR;							\
 	}								\
     }									\
@@ -2430,7 +2440,20 @@ typedef struct mips_args {
 #define ENCODE_SECTION_INFO(DECL)					\
 do									\
   {									\
-    if (TARGET_GP_OPT && TREE_CODE (DECL) == VAR_DECL)			\
+    if (TARGET_EMBEDDED_PIC)						\
+      {									\
+        if (TREE_CODE (DECL) == VAR_DECL)				\
+	  SYMBOL_REF_FLAG (XEXP (DECL_RTL (DECL), 0)) = 1;		\
+        else if (TREE_CODE (DECL) == FUNCTION_DECL)			\
+	  SYMBOL_REF_FLAG (XEXP (DECL_RTL (DECL), 0)) = 0;		\
+	else if (TREE_CODE (DECL) == STRING_CST				\
+		 && ! flag_writable_strings)				\
+	  SYMBOL_REF_FLAG (XEXP (TREE_CST_RTL (DECL), 0)) = 0;		\
+        else								\
+	  SYMBOL_REF_FLAG (XEXP (TREE_CST_RTL (DECL), 0)) = 1;		\
+      }									\
+									\
+    else if (TARGET_GP_OPT && TREE_CODE (DECL) == VAR_DECL)		\
       {									\
 	int size = int_size_in_bytes (TREE_TYPE (DECL));		\
 									\
diff --git a/gcc/config/mips/mips.md b/gcc/config/mips/mips.md
index be9e1512a06b..dfe0dad17885 100644
--- a/gcc/config/mips/mips.md
+++ b/gcc/config/mips/mips.md
@@ -2759,6 +2759,23 @@ move\\t%0,%z4\\n\\
   ""
   "
 {
+  /* If we are generating embedded PIC code, and we are referring to a
+     symbol in the .text section, we must use an offset from the start
+     of the function.  */
+  if (TARGET_EMBEDDED_PIC
+      && (GET_CODE (operands[1]) == LABEL_REF
+	  || (GET_CODE (operands[1]) == SYMBOL_REF
+	      && ! SYMBOL_REF_FLAG (operands[1]))))
+    {
+      rtx temp;
+
+      temp = embedded_pic_offset (operands[1]);
+      temp = gen_rtx (PLUS, Pmode, embedded_pic_fnaddr_rtx,
+		      force_reg (SImode, temp));
+      emit_move_insn (operands[0], force_reg (SImode, temp));
+      DONE;
+    }
+
   /* If operands[1] is a constant address illegal for pic, then we need to
      handle it just like LEGITIMIZE_ADDRESS does.  */
   if (flag_pic && pic_address_needs_scratch (operands[1]))
@@ -5542,6 +5559,20 @@ move\\t%0,%z4\\n\\
 ;;     }
 ;; }")
 
+;; When generating embedded PIC code we need to get the address of the
+;; current function.  This specialized instruction does just that.
+
+(define_insn "get_fnaddr"
+  [(set (match_operand 0 "register_operand" "d")
+	(unspec [(match_operand 1 "" "")] 1))
+   (clobber (reg:SI 31))]
+  "TARGET_EMBEDDED_PIC
+   && GET_CODE (operands[1]) == SYMBOL_REF"
+  "%($LF%= = . + 8\;bal\\t$LF%=\;la\\t%0,%1-$LF%=%)\;addu\\t%0,%0,$31"
+  [(set_attr "type"	"call")
+   (set_attr "mode"	"none")
+   (set_attr "length"	"4")])
+
 
 ;;
 ;;  ....................