Fix PR target/46729

[Eric Botcazou <ebotcazou at adacore dot com>]

The failures present in the libstdc++-v3 testsuite on SPARC/Solaris 10 with 
the Sun assembler show that the initial-exec TLS support is broken for this 
combination; on the contrary, it works with the GNU assembler.  The problem 
is that Sun as always emits PC-relative relocations for the GOT symbol, even 
in non-PIC mode, with the 32-bit ABI, unlike GNU as.

The attached patch fixes that by reloading the GOT register by means of the 
load_pcrel_sym{si,di} patterns each time it is used.  This uncovered a small 
weakness in these patterns, namely that they don't declare the dependency on 
the register number of the helper function they use.

Bootstrapped/regtested on SPARC/Solaris and SPARC64/Solaris, both with the Sun 
and the GNU assemblers, applied on the mainline and 4.5 branch.


2010-12-19  Eric Botcazou  <ebotcazou@adacore.com>

	PR target/46729
	* config/sparc/sparc.h (GLOBAL_OFFSET_TABLE_REGNUM): New macro.
	(PIC_OFFSET_TABLE_REGNUM): Rewrite in terms of above macro.
	* config/sparc/sparc.c (pic_helper_needed): Delete.
	(global_offset_table): Likewise.
	(pic_helper_symbol): Rename to...
	(got_helper_rtx): ...this.
	(global_offset_table_rtx): New global variable.
	(sparc_got_symbol): Likewise.
	(sparc_got): New static function.
	(check_pic): Use local variable and call sparc_got.
	(sparc_tls_symbol): Initialize to NULL_RTX.
	(sparc_tls_got): In non-PIC mode, reload the GOT register for Sun TLS
	and 32-bit ABI and copy the GOT symbol to a new register otherwise.
	(get_pc_thunk_name): Rename local variable.
	(gen_load_pcrel_sym): New wrapper around load_pcrel_sym{si,di}.
	(load_pic_register): Rename to...
	(load_got_register): ...this.  Adjust and call gen_load_pcrel_sym.
	(sparc_expand_prologue): Do not test flag_pic.
	(sparc_output_mi_thunk): Use pic_offset_table_rtx directly.
	(sparc_file_end): Test got_helper_rtx instead of pic_helper_needed.
	Rename local variable and do not call get_pc_thunk_name again.
	* config/sparc/sparc.md (load_pcrel_sym): Add operand #3.


-- 
Eric Botcazou

Index: config/sparc/sparc.md
===================================================================
--- config/sparc/sparc.md	(revision 167957)
+++ config/sparc/sparc.md	(working copy)
@@ -1113,14 +1113,15 @@ (define_insn "*inverted_int_branch_sp64"
 
 ;; Load in operand 0 the (absolute) address of operand 1, which is a symbolic
 ;; value subject to a PC-relative relocation.  Operand 2 is a helper function
-;; that adds the PC value at the call point to operand 0.
+;; that adds the PC value at the call point to register #(operand 3).
 
 (define_insn "load_pcrel_sym<P:mode>"
   [(set (match_operand:P 0 "register_operand" "=r")
 	(unspec:P [(match_operand:P 1 "symbolic_operand" "")
-		   (match_operand:P 2 "call_address_operand" "")] UNSPEC_LOAD_PCREL_SYM))
+		   (match_operand:P 2 "call_address_operand" "")
+		   (match_operand:P 3 "const_int_operand" "")] UNSPEC_LOAD_PCREL_SYM))
    (clobber (reg:P 15))]
-  ""
+  "REGNO (operands[0]) == INTVAL (operands[3])"
 {
   if (flag_delayed_branch)
     return "sethi\t%%hi(%a1-4), %0\n\tcall\t%a2\n\t add\t%0, %%lo(%a1+4), %0";
Index: config/sparc/sparc.c
===================================================================
--- config/sparc/sparc.c	(revision 167957)
+++ config/sparc/sparc.c	(working copy)
@@ -391,7 +391,7 @@ static rtx sparc_builtin_saveregs (void)
 static int epilogue_renumber (rtx *, int);
 static bool sparc_assemble_integer (rtx, unsigned int, int);
 static int set_extends (rtx);
-static void load_pic_register (void);
+static void load_got_register (void);
 static int save_or_restore_regs (int, int, rtx, int, int);
 static void emit_save_or_restore_regs (int);
 static void sparc_asm_function_prologue (FILE *, HOST_WIDE_INT);
@@ -3020,26 +3020,39 @@ sparc_cannot_force_const_mem (rtx x)
     }
 }
 
-/* PIC support.  */
-static GTY(()) bool pic_helper_needed = false;
-static GTY(()) rtx pic_helper_symbol;
-static GTY(()) rtx global_offset_table;
+/* Global Offset Table support.  */
+static GTY(()) rtx got_helper_rtx = NULL_RTX;
+static GTY(()) rtx global_offset_table_rtx = NULL_RTX;
+
+/* Return the SYMBOL_REF for the Global Offset Table.  */
+
+static GTY(()) rtx sparc_got_symbol = NULL_RTX;
+
+static rtx
+sparc_got (void)
+{
+  if (!sparc_got_symbol)
+    sparc_got_symbol = gen_rtx_SYMBOL_REF (Pmode, "_GLOBAL_OFFSET_TABLE_");
+
+  return sparc_got_symbol;
+}
 
 /* Ensure that we are not using patterns that are not OK with PIC.  */
 
 int
 check_pic (int i)
 {
+  rtx op;
+
   switch (flag_pic)
     {
     case 1:
-      gcc_assert (GET_CODE (recog_data.operand[i]) != SYMBOL_REF
-	  	  && (GET_CODE (recog_data.operand[i]) != CONST
-	          || (GET_CODE (XEXP (recog_data.operand[i], 0)) == MINUS
-		      && (XEXP (XEXP (recog_data.operand[i], 0), 0)
-			  == global_offset_table)
-		      && (GET_CODE (XEXP (XEXP (recog_data.operand[i], 0), 1))
-			  == CONST))));
+      op = recog_data.operand[i];
+      gcc_assert (GET_CODE (op) != SYMBOL_REF
+	  	  && (GET_CODE (op) != CONST
+		      || (GET_CODE (XEXP (op, 0)) == MINUS
+			  && XEXP (XEXP (op, 0), 0) == sparc_got ()
+			  && GET_CODE (XEXP (XEXP (op, 0), 1)) == CONST)));
     case 2:
     default:
       return 1;
@@ -3274,9 +3287,9 @@ sparc_legitimate_address_p (enum machine
   return 1;
 }
 
-/* Construct the SYMBOL_REF for the tls_get_offset function.  */
+/* Return the SYMBOL_REF for the tls_get_addr function.  */
 
-static GTY(()) rtx sparc_tls_symbol;
+static GTY(()) rtx sparc_tls_symbol = NULL_RTX;
 
 static rtx
 sparc_tls_get_addr (void)
@@ -3287,21 +3300,28 @@ sparc_tls_get_addr (void)
   return sparc_tls_symbol;
 }
 
+/* Return the Global Offset Table to be used in TLS mode.  */
+
 static rtx
 sparc_tls_got (void)
 {
-  rtx temp;
+  /* In PIC mode, this is just the PIC offset table.  */
   if (flag_pic)
     {
       crtl->uses_pic_offset_table = 1;
       return pic_offset_table_rtx;
     }
 
-  if (!global_offset_table)
-    global_offset_table = gen_rtx_SYMBOL_REF (Pmode, "_GLOBAL_OFFSET_TABLE_");
-  temp = gen_reg_rtx (Pmode);
-  emit_move_insn (temp, global_offset_table);
-  return temp;
+  /* In non-PIC mode, Sun as (unlike GNU as) emits PC-relative relocations for
+     the GOT symbol with the 32-bit ABI, so we reload the GOT register.  */
+  if (TARGET_SUN_TLS && TARGET_ARCH32)
+    {
+      load_got_register ();
+      return global_offset_table_rtx;
+    }
+
+  /* In all other cases, we load a new pseudo with the GOT symbol.  */
+  return copy_to_reg (sparc_got ());
 }
 
 /* Return true if X contains a thread-local symbol.  */
@@ -3741,59 +3761,69 @@ sparc_mode_dependent_address_p (const_rt
 static void
 get_pc_thunk_name (char name[32], unsigned int regno)
 {
-  const char *pic_name = reg_names[regno];
+  const char *reg_name = reg_names[regno];
 
   /* Skip the leading '%' as that cannot be used in a
      symbol name.  */
-  pic_name += 1;
+  reg_name += 1;
 
   if (USE_HIDDEN_LINKONCE)
-    sprintf (name, "__sparc_get_pc_thunk.%s", pic_name);
+    sprintf (name, "__sparc_get_pc_thunk.%s", reg_name);
   else
     ASM_GENERATE_INTERNAL_LABEL (name, "LADDPC", regno);
 }
 
-/* Emit code to load the PIC register.  */
+/* Wrapper around the load_pcrel_sym{si,di} patterns.  */
 
-static void
-load_pic_register (void)
+static rtx
+gen_load_pcrel_sym (rtx op0, rtx op1, rtx op2, rtx op3)
 {
   int orig_flag_pic = flag_pic;
+  rtx insn;
 
-  if (TARGET_VXWORKS_RTP)
-    {
-      emit_insn (gen_vxworks_load_got ());
-      emit_use (pic_offset_table_rtx);
-      return;
-    }
-
-  /* If we haven't initialized the special PIC symbols, do so now.  */
-  if (!pic_helper_needed)
-    {
-      char name[32];
+  /* The load_pcrel_sym{si,di} patterns require absolute addressing.  */
+  flag_pic = 0;
+  if (TARGET_ARCH64)
+    insn = gen_load_pcrel_symdi (op0, op1, op2, op3);
+  else
+    insn = gen_load_pcrel_symsi (op0, op1, op2, op3);
+  flag_pic = orig_flag_pic;
 
-      pic_helper_needed = true;
+  return insn;
+}
 
-      get_pc_thunk_name (name, REGNO (pic_offset_table_rtx));
-      pic_helper_symbol = gen_rtx_SYMBOL_REF (Pmode, ggc_strdup (name));
+/* Emit code to load the GOT register.  */
 
-      global_offset_table = gen_rtx_SYMBOL_REF (Pmode, "_GLOBAL_OFFSET_TABLE_");
-    }
+static void
+load_got_register (void)
+{
+  /* In PIC mode, this will retrieve pic_offset_table_rtx.  */
+  if (!global_offset_table_rtx)
+    global_offset_table_rtx = gen_rtx_REG (Pmode, GLOBAL_OFFSET_TABLE_REGNUM);
 
-  flag_pic = 0;
-  if (TARGET_ARCH64)
-    emit_insn (gen_load_pcrel_symdi (pic_offset_table_rtx, global_offset_table,
-				     pic_helper_symbol));
+  if (TARGET_VXWORKS_RTP)
+    emit_insn (gen_vxworks_load_got ());
   else
-    emit_insn (gen_load_pcrel_symsi (pic_offset_table_rtx, global_offset_table,
-				     pic_helper_symbol));
-  flag_pic = orig_flag_pic;
+    {
+      /* The GOT symbol is subject to a PC-relative relocation so we need a
+	 helper function to add the PC value and thus get the final value.  */
+      if (!got_helper_rtx)
+	{
+	  char name[32];
+	  get_pc_thunk_name (name, GLOBAL_OFFSET_TABLE_REGNUM);
+	  got_helper_rtx = gen_rtx_SYMBOL_REF (Pmode, ggc_strdup (name));
+	}
+
+      emit_insn (gen_load_pcrel_sym (global_offset_table_rtx, sparc_got (),
+				     got_helper_rtx,
+				     GEN_INT (GLOBAL_OFFSET_TABLE_REGNUM)));
+    }
 
   /* Need to emit this whether or not we obey regdecls,
      since setjmp/longjmp can cause life info to screw up.
      ??? In the case where we don't obey regdecls, this is not sufficient
      since we may not fall out the bottom.  */
-  emit_use (pic_offset_table_rtx);
+  emit_use (global_offset_table_rtx);
 }
 
 /* Emit a call instruction with the pattern given by PAT.  ADDR is the
@@ -4479,7 +4509,7 @@ gen_stack_pointer_dec (rtx decrement)
 
 /* Expand the function prologue.  The prologue is responsible for reserving
    storage for the frame, saving the call-saved registers and loading the
-   PIC register if needed.  */
+   GOT register if needed.  */
 
 void
 sparc_expand_prologue (void)
@@ -4587,9 +4617,9 @@ sparc_expand_prologue (void)
   if (num_gfregs)
     emit_save_or_restore_regs (SORR_SAVE);
 
-  /* Load the PIC register if needed.  */
-  if (flag_pic && crtl->uses_pic_offset_table)
-    load_pic_register ();
+  /* Load the GOT register if needed.  */
+  if (crtl->uses_pic_offset_table)
+    load_got_register ();
 }
 
 /* This function generates the assembly code for function entry, which boils
@@ -9157,7 +9187,7 @@ sparc_rtx_costs (rtx x, int code, int ou
 /* Emit the sequence of insns SEQ while preserving the registers REG and REG2.
    This is achieved by means of a manual dynamic stack space allocation in
    the current frame.  We make the assumption that SEQ doesn't contain any
-   function calls, with the possible exception of calls to the PIC helper.  */
+   function calls, with the possible exception of calls to the GOT helper.  */
 
 static void
 emit_and_preserve (rtx seq, rtx reg, rtx reg2)
@@ -9320,20 +9350,19 @@ sparc_output_mi_thunk (FILE *file, tree
     {
       /* The hoops we have to jump through in order to generate a sibcall
 	 without using delay slots...  */
-      rtx spill_reg, spill_reg2, seq, scratch = gen_rtx_REG (Pmode, 1);
+      rtx spill_reg, seq, scratch = gen_rtx_REG (Pmode, 1);
 
       if (flag_pic)
         {
 	  spill_reg = gen_rtx_REG (word_mode, 15);  /* %o7 */
-	  spill_reg2 = gen_rtx_REG (word_mode, PIC_OFFSET_TABLE_REGNUM);
 	  start_sequence ();
-	  /* Delay emitting the PIC helper function because it needs to
+	  /* Delay emitting the GOT helper function because it needs to
 	     change the section and we are emitting assembly code.  */
-	  load_pic_register ();  /* clobbers %o7 */
+	  load_got_register ();  /* clobbers %o7 */
 	  scratch = sparc_legitimize_pic_address (funexp, scratch);
 	  seq = get_insns ();
 	  end_sequence ();
-	  emit_and_preserve (seq, spill_reg, spill_reg2);
+	  emit_and_preserve (seq, spill_reg, pic_offset_table_rtx);
 	}
       else if (TARGET_ARCH32)
 	{
@@ -9484,17 +9513,15 @@ sparc_output_dwarf_dtprel (FILE *file, i
 static void
 sparc_file_end (void)
 {
-  /* If need to emit the special PIC helper function, do so now.  */
-  if (pic_helper_needed)
+  /* If we need to emit the special GOT helper function, do so now.  */
+  if (got_helper_rtx)
     {
-      unsigned int regno = REGNO (pic_offset_table_rtx);
-      const char *pic_name = reg_names[regno];
-      char name[32];
+      const char *name = XSTR (got_helper_rtx, 0);
+      const char *reg_name = reg_names[GLOBAL_OFFSET_TABLE_REGNUM];
 #ifdef DWARF2_UNWIND_INFO
       bool do_cfi;
 #endif
 
-      get_pc_thunk_name (name, regno);
       if (USE_HIDDEN_LINKONCE)
 	{
 	  tree decl = build_decl (BUILTINS_LOCATION, FUNCTION_DECL,
@@ -9529,10 +9556,10 @@ sparc_file_end (void)
 #endif
       if (flag_delayed_branch)
 	fprintf (asm_out_file, "\tjmp\t%%o7+8\n\t add\t%%o7, %s, %s\n",
-		 pic_name, pic_name);
+		 reg_name, reg_name);
       else
 	fprintf (asm_out_file, "\tadd\t%%o7, %s, %s\n\tjmp\t%%o7+8\n\t nop\n",
-		 pic_name, pic_name);
+		 reg_name, reg_name);
 #ifdef DWARF2_UNWIND_INFO
       if (do_cfi)
 	fprintf (asm_out_file, "\t.cfi_endproc\n");
Index: config/sparc/sparc.h
===================================================================
--- config/sparc/sparc.h	(revision 167957)
+++ config/sparc/sparc.h	(working copy)
@@ -906,10 +906,15 @@ extern int sparc_mode_class[];
    not be a register used by the prologue.  */
 #define STATIC_CHAIN_REGNUM (TARGET_ARCH64 ? 5 : 2)
 
+/* Register which holds the global offset table, if any.  */
+
+#define GLOBAL_OFFSET_TABLE_REGNUM 23
+
 /* Register which holds offset table for position-independent
    data references.  */
 
-#define PIC_OFFSET_TABLE_REGNUM (flag_pic ? 23 : INVALID_REGNUM)
+#define PIC_OFFSET_TABLE_REGNUM \
+  (flag_pic ? GLOBAL_OFFSET_TABLE_REGNUM : INVALID_REGNUM)
 
 /* Pick a default value we can notice from override_options:
    !v9: Default is on.