re PR target/65810 (powerpc64 alignment of r2 insufficient for loading long-double constants)

	PR target/65810
	* config/rs6000/rs6000.c (POWERPC64_TOC_POINTER_ALIGNMENT): Define.
	(offsettable_ok_by_alignment): Use minimum of decl and toc
	pointer alignment.  Replace dead code with assertion.
	(use_toc_relative_ref): Add mode arg.  Return false in -mcmodel=medium
	case if size exceeds toc pointer alignment.
	(rs6000_legitimize_reload_address): Update use_toc_relative_ref call.
	(rs6000_emit_move): Likewise.
	* configure.ac: Add linker toc pointer alignment check.
	* configure: Regenerate.
	* config.in: Regenerate.

From-SVN: r222498

1 files changed, 24 insertions, 33 deletions

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 3245d46..c74c7d1 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -6524,13 +6524,21 @@ virtual_stack_registers_memory_p (rtx op)
 }
 
 /* Return true if a MODE sized memory accesses to OP plus OFFSET
-   is known to not straddle a 32k boundary.  */
+   is known to not straddle a 32k boundary.  This function is used
+   to determine whether -mcmodel=medium code can use TOC pointer
+   relative addressing for OP.  This means the alignment of the TOC
+   pointer must also be taken into account, and unfortunately that is
+   only 8 bytes.  */ 
+
+#ifndef POWERPC64_TOC_POINTER_ALIGNMENT
+#define POWERPC64_TOC_POINTER_ALIGNMENT 8
+#endif
 
 static bool
 offsettable_ok_by_alignment (rtx op, HOST_WIDE_INT offset,
 			     machine_mode mode)
 {
-  tree decl, type;
+  tree decl;
   unsigned HOST_WIDE_INT dsize, dalign, lsb, mask;
 
   if (GET_CODE (op) != SYMBOL_REF)
@@ -6583,38 +6591,20 @@ offsettable_ok_by_alignment (rtx op, HOST_WIDE_INT offset,
 	  if (dsize > 32768)
 	    return false;
 
-	  return dalign / BITS_PER_UNIT >= dsize;
+	  dalign /= BITS_PER_UNIT;
+	  if (dalign > POWERPC64_TOC_POINTER_ALIGNMENT)
+	    dalign = POWERPC64_TOC_POINTER_ALIGNMENT;
+	  return dalign >= dsize;
 	}
     }
   else
-    {
-      type = TREE_TYPE (decl);
-
-      dalign = TYPE_ALIGN (type);
-      if (CONSTANT_CLASS_P (decl))
-	dalign = CONSTANT_ALIGNMENT (decl, dalign);
-      else
-	dalign = DATA_ALIGNMENT (decl, dalign);
-
-      if (dsize == 0)
-	{
-	  /* BLKmode, check the entire object.  */
-	  if (TREE_CODE (decl) == STRING_CST)
-	    dsize = TREE_STRING_LENGTH (decl);
-	  else if (TYPE_SIZE_UNIT (type)
-		   && tree_fits_uhwi_p (TYPE_SIZE_UNIT (type)))
-	    dsize = tree_to_uhwi (TYPE_SIZE_UNIT (type));
-	  else
-	    return false;
-	  if (dsize > 32768)
-	    return false;
-
-	  return dalign / BITS_PER_UNIT >= dsize;
-	}
-    }
+    gcc_unreachable ();
 
   /* Find how many bits of the alignment we know for this access.  */
-  mask = dalign / BITS_PER_UNIT - 1;
+  dalign /= BITS_PER_UNIT;
+  if (dalign > POWERPC64_TOC_POINTER_ALIGNMENT)
+    dalign = POWERPC64_TOC_POINTER_ALIGNMENT;
+  mask = dalign - 1;
   lsb = offset & -offset;
   mask &= lsb - 1;
   dalign = mask + 1;
@@ -7553,13 +7543,14 @@ rs6000_cannot_force_const_mem (machine_mode mode ATTRIBUTE_UNUSED, rtx x)
    can be addressed relative to the toc pointer.  */
 
 static bool
-use_toc_relative_ref (rtx sym)
+use_toc_relative_ref (rtx sym, machine_mode mode)
 {
   return ((constant_pool_expr_p (sym)
 	   && ASM_OUTPUT_SPECIAL_POOL_ENTRY_P (get_pool_constant (sym),
 					       get_pool_mode (sym)))
 	  || (TARGET_CMODEL == CMODEL_MEDIUM
-	      && SYMBOL_REF_LOCAL_P (sym)));
+	      && SYMBOL_REF_LOCAL_P (sym)
+	      && GET_MODE_SIZE (mode) <= POWERPC64_TOC_POINTER_ALIGNMENT));
 }
 
 /* Our implementation of LEGITIMIZE_RELOAD_ADDRESS.  Returns a value to
@@ -7764,7 +7755,7 @@ rs6000_legitimize_reload_address (rtx x, machine_mode mode,
   if (TARGET_TOC
       && reg_offset_p
       && GET_CODE (x) == SYMBOL_REF
-      && use_toc_relative_ref (x))
+      && use_toc_relative_ref (x, mode))
     {
       x = create_TOC_reference (x, NULL_RTX);
       if (TARGET_CMODEL != CMODEL_SMALL)
@@ -8842,7 +8833,7 @@ rs6000_emit_move (rtx dest, rtx source, machine_mode mode)
 	 reference to it.  */
       if (TARGET_TOC
 	  && GET_CODE (operands[1]) == SYMBOL_REF
-	  && use_toc_relative_ref (operands[1]))
+	  && use_toc_relative_ref (operands[1], mode))
 	operands[1] = create_TOC_reference (operands[1], operands[0]);
       else if (mode == Pmode
 	       && CONSTANT_P (operands[1])