PR fortran/90903 [part2] - Add runtime checking for the MVBITS intrinsic

Implement inline expansion of the intrinsic elemental subroutine MVBITS
with optional runtime checks for valid argument range.

gcc/fortran/ChangeLog:

	* iresolve.c (gfc_resolve_mvbits): Remove unneeded conversion of
	FROMPOS, LEN and TOPOS arguments to fit a C int.
	* trans-intrinsic.c (gfc_conv_intrinsic_mvbits): Add inline
	expansion of MVBITS intrinsic elemental subroutine and add code
	for runtime argument checking.
	(gfc_conv_intrinsic_subroutine): Recognise MVBITS intrinsic, but
	defer handling to gfc_trans_call.
	* trans-stmt.c (replace_ss):
	(gfc_trans_call): Adjust to handle inline expansion, scalarization
	of intrinsic subroutine MVBITS in gfc_conv_intrinsic_mvbits.
	* trans.h (gfc_conv_intrinsic_mvbits): Add prototype for
	gfc_conv_intrinsic_mvbits.

gcc/testsuite/ChangeLog:

	* gfortran.dg/check_bits_2.f90: New test.

Co-authored-by: Paul Thomas  <pault@gcc.gnu.org>

1 files changed, 167 insertions, 0 deletions

diff --git a/gcc/fortran/trans-intrinsic.c b/gcc/fortran/trans-intrinsic.c
index 32fe988..3b3bd86 100644
--- a/gcc/fortran/trans-intrinsic.c
+++ b/gcc/fortran/trans-intrinsic.c
@@ -11790,6 +11790,169 @@ conv_intrinsic_event_query (gfc_code *code)
   return gfc_finish_block (&se.pre);
 }
 
+
+/* This is a peculiar case because of the need to do dependency checking.
+   It is called via trans-stmt.c(gfc_trans_call), where it is picked out as
+   a special case and this function called instead of
+   gfc_conv_procedure_call.  */
+void
+gfc_conv_intrinsic_mvbits (gfc_se *se, gfc_actual_arglist *actual_args,
+			   gfc_loopinfo *loop)
+{
+  gfc_actual_arglist *actual;
+  gfc_se argse[5];
+  gfc_expr *arg[5];
+  gfc_ss *lss;
+  int n;
+
+  tree from, frompos, len, to, topos;
+  tree lenmask, oldbits, newbits, bitsize;
+  tree type, utype, above, mask1, mask2;
+
+  if (loop)
+    lss = loop->ss;
+  else
+    lss = gfc_ss_terminator;
+
+  actual = actual_args;
+  for (n = 0; n < 5; n++, actual = actual->next)
+    {
+      arg[n] = actual->expr;
+      gfc_init_se (&argse[n], NULL);
+
+      if (lss != gfc_ss_terminator)
+	{
+	  gfc_copy_loopinfo_to_se (&argse[n], loop);
+	  /* Find the ss for the expression if it is there.  */
+	  argse[n].ss = lss;
+	  gfc_mark_ss_chain_used (lss, 1);
+	}
+
+      gfc_conv_expr (&argse[n], arg[n]);
+
+      if (loop)
+	lss = argse[n].ss;
+    }
+
+  from    = argse[0].expr;
+  frompos = argse[1].expr;
+  len     = argse[2].expr;
+  to      = argse[3].expr;
+  topos   = argse[4].expr;
+
+  /* The type of the result (TO).  */
+  type    = TREE_TYPE (to);
+  bitsize = build_int_cst (integer_type_node, TYPE_PRECISION (type));
+
+  /* Optionally generate code for runtime argument check.  */
+  if (gfc_option.rtcheck & GFC_RTCHECK_BITS)
+    {
+      tree nbits, below, ccond;
+      tree fp = fold_convert (long_integer_type_node, frompos);
+      tree ln = fold_convert (long_integer_type_node, len);
+      tree tp = fold_convert (long_integer_type_node, topos);
+      below = fold_build2_loc (input_location, LT_EXPR,
+			       logical_type_node, frompos,
+			       build_int_cst (TREE_TYPE (frompos), 0));
+      above = fold_build2_loc (input_location, GT_EXPR,
+			       logical_type_node, frompos,
+			       fold_convert (TREE_TYPE (frompos), bitsize));
+      ccond = fold_build2_loc (input_location, TRUTH_ORIF_EXPR,
+			       logical_type_node, below, above);
+      gfc_trans_runtime_check (true, false, ccond, &argse[1].pre,
+			       &arg[1]->where,
+			       "FROMPOS argument (%ld) out of range 0:%d "
+			       "in intrinsic MVBITS", fp, bitsize);
+      below = fold_build2_loc (input_location, LT_EXPR,
+			       logical_type_node, len,
+			       build_int_cst (TREE_TYPE (len), 0));
+      above = fold_build2_loc (input_location, GT_EXPR,
+			       logical_type_node, len,
+			       fold_convert (TREE_TYPE (len), bitsize));
+      ccond = fold_build2_loc (input_location, TRUTH_ORIF_EXPR,
+			       logical_type_node, below, above);
+      gfc_trans_runtime_check (true, false, ccond, &argse[2].pre,
+			       &arg[2]->where,
+			       "LEN argument (%ld) out of range 0:%d "
+			       "in intrinsic MVBITS", ln, bitsize);
+      below = fold_build2_loc (input_location, LT_EXPR,
+			       logical_type_node, topos,
+			       build_int_cst (TREE_TYPE (topos), 0));
+      above = fold_build2_loc (input_location, GT_EXPR,
+			       logical_type_node, topos,
+			       fold_convert (TREE_TYPE (topos), bitsize));
+      ccond = fold_build2_loc (input_location, TRUTH_ORIF_EXPR,
+			       logical_type_node, below, above);
+      gfc_trans_runtime_check (true, false, ccond, &argse[4].pre,
+			       &arg[4]->where,
+			       "TOPOS argument (%ld) out of range 0:%d "
+			       "in intrinsic MVBITS", tp, bitsize);
+
+      /* The tests above ensure that FROMPOS, LEN and TOPOS fit into short
+	 integers.  Additions below cannot overflow.  */
+      nbits = fold_convert (long_integer_type_node, bitsize);
+      above = fold_build2_loc (input_location, PLUS_EXPR,
+			       long_integer_type_node, fp, ln);
+      ccond = fold_build2_loc (input_location, GT_EXPR,
+			       logical_type_node, above, nbits);
+      gfc_trans_runtime_check (true, false, ccond, &argse[1].pre,
+			       &arg[1]->where,
+			       "FROMPOS(%ld)+LEN(%ld)>BIT_SIZE(%d) "
+			       "in intrinsic MVBITS", fp, ln, bitsize);
+      above = fold_build2_loc (input_location, PLUS_EXPR,
+			       long_integer_type_node, tp, ln);
+      ccond = fold_build2_loc (input_location, GT_EXPR,
+			       logical_type_node, above, nbits);
+      gfc_trans_runtime_check (true, false, ccond, &argse[4].pre,
+			       &arg[4]->where,
+			       "TOPOS(%ld)+LEN(%ld)>BIT_SIZE(%d) "
+			       "in intrinsic MVBITS", tp, ln, bitsize);
+    }
+
+  for (n = 0; n < 5; n++)
+    {
+      gfc_add_block_to_block (&se->pre, &argse[n].pre);
+      gfc_add_block_to_block (&se->post, &argse[n].post);
+    }
+
+  /* lenmask = (LEN >= bit_size (TYPE)) ? ~(TYPE)0 : ((TYPE)1 << LEN) - 1  */
+  above = fold_build2_loc (input_location, GE_EXPR, logical_type_node,
+			   len, fold_convert (TREE_TYPE (len), bitsize));
+  mask1 = build_int_cst (type, -1);
+  mask2 = fold_build2_loc (input_location, LSHIFT_EXPR, type,
+			   build_int_cst (type, 1), len);
+  mask2 = fold_build2_loc (input_location, MINUS_EXPR, type,
+			   mask2, build_int_cst (type, 1));
+  lenmask = fold_build3_loc (input_location, COND_EXPR, type,
+			     above, mask1, mask2);
+
+  /* newbits = (((UTYPE)(FROM) >> FROMPOS) & lenmask) << TOPOS.
+   * For valid frompos+len <= bit_size(FROM) the conversion to unsigned is
+   * not strictly necessary; artificial bits from rshift will be masked.  */
+  utype = unsigned_type_for (type);
+  newbits = fold_build2_loc (input_location, RSHIFT_EXPR, utype,
+			     fold_convert (utype, from), frompos);
+  newbits = fold_build2_loc (input_location, BIT_AND_EXPR, type,
+			     fold_convert (type, newbits), lenmask);
+  newbits = fold_build2_loc (input_location, LSHIFT_EXPR, type,
+			     newbits, topos);
+
+  /* oldbits = TO & (~(lenmask << TOPOS)).  */
+  oldbits = fold_build2_loc (input_location, LSHIFT_EXPR, type,
+			     lenmask, topos);
+  oldbits = fold_build1_loc (input_location, BIT_NOT_EXPR, type, oldbits);
+  oldbits = fold_build2_loc (input_location, BIT_AND_EXPR, type, oldbits, to);
+
+  /* TO = newbits | oldbits.  */
+  se->expr = fold_build2_loc (input_location, BIT_IOR_EXPR, type,
+			      oldbits, newbits);
+
+  /* Return the assignment.  */
+  se->expr = fold_build2_loc (input_location, MODIFY_EXPR,
+			      void_type_node, to, se->expr);
+}
+
+
 static tree
 conv_intrinsic_move_alloc (gfc_code *code)
 {
@@ -12119,6 +12282,10 @@ gfc_conv_intrinsic_subroutine (gfc_code *code)
       res = conv_intrinsic_kill_sub (code);
       break;
 
+    case GFC_ISYM_MVBITS:
+      res = NULL_TREE;
+      break;
+
     case GFC_ISYM_SYSTEM_CLOCK:
       res = conv_intrinsic_system_clock (code);
       break;