[PATCH v2 7/7] fortran: Ignore unused args in scalarization [PR97896]

[Mikael Morin <mikael@gcc.gnu.org>]

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The KIND argument of the INDEX intrinsic is a compile time constant
that is used at compile time only to resolve to a kind-specific library
method.  It is otherwise completely ignored at runtime, and there is
no code generated for it as the library procedure has no kind argument.
This confuses the scalarizer which expects to see every argument
of elemental functions to be used when calling a procedure.
This change removes the argument from the scalarization lists
at the beginning of the scalarization process, so that the argument
is completely ignored.

gcc/fortran/
	PR fortran/97896
	* interface.c (gfc_dummy_arg_get_name): New function.
	* gfortran.h (gfc_dummy_arg_get_name): Declare it.
	* trans-array.h (gfc_get_intrinsic_for_expr,
	gfc_get_proc_ifc_for_expr): New.
	* trans-array.c (gfc_get_intrinsic_for_expr,
	arg_evaluated_for_scalarization): New.
	(gfc_walk_elemental_function_args): Add intrinsic procedure
	as argument.  Check arg_evaluated_for_scalarization.
	* trans-intrinsic.c (gfc_walk_intrinsic_function): Update call.
	* trans-stmt.c (get_intrinsic_for_code): New.
	(gfc_trans_call): Update call.

gcc/testsuite/
	PR fortran/97896
	* gfortran.dg/index_5.f90: New.
---
 gcc/fortran/gfortran.h                |  1 +
 gcc/fortran/interface.c               | 17 +++++++++
 gcc/fortran/trans-array.c             | 51 ++++++++++++++++++++++++++-
 gcc/fortran/trans-array.h             |  3 ++
 gcc/fortran/trans-intrinsic.c         |  1 +
 gcc/fortran/trans-stmt.c              | 20 +++++++++++
 gcc/testsuite/gfortran.dg/index_5.f90 | 23 ++++++++++++
 7 files changed, 115 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gfortran.dg/index_5.f90


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diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index 5a28d1408eb..4035d260498 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -2196,6 +2196,7 @@ struct gfc_dummy_arg
 #define gfc_get_dummy_arg() XCNEW (gfc_dummy_arg)
 
 
+const char * gfc_dummy_arg_get_name (gfc_dummy_arg &);
 const gfc_typespec & gfc_dummy_arg_get_typespec (gfc_dummy_arg &);
 bool gfc_dummy_arg_is_optional (gfc_dummy_arg &);
 
diff --git a/gcc/fortran/interface.c b/gcc/fortran/interface.c
index 7289374e932..22aa916c88e 100644
--- a/gcc/fortran/interface.c
+++ b/gcc/fortran/interface.c
@@ -5400,6 +5400,23 @@ gfc_get_formal_from_actual_arglist (gfc_symbol *sym,
 }
 
 
+const char *
+gfc_dummy_arg_get_name (gfc_dummy_arg & dummy_arg)
+{
+  switch (dummy_arg.kind)
+    {
+    case GFC_INTRINSIC_DUMMY_ARG:
+      return dummy_arg.u.intrinsic->name;
+
+    case GFC_NON_INTRINSIC_DUMMY_ARG:
+      return dummy_arg.u.non_intrinsic->sym->name;
+
+    default:
+      gcc_unreachable ();
+    }
+}
+
+
 const gfc_typespec &
 gfc_dummy_arg_get_typespec (gfc_dummy_arg & dummy_arg)
 {
diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index 6ae72a354e5..96b0a2583b0 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -11201,6 +11201,51 @@ gfc_get_proc_ifc_for_expr (gfc_expr *procedure_ref)
 }
 
 
+/* Given an expression referring to an intrinsic function call,
+   return the intrinsic symbol.  */
+
+gfc_intrinsic_sym *
+gfc_get_intrinsic_for_expr (gfc_expr *call)
+{
+  if (call == NULL)
+    return NULL;
+
+  /* Normal procedure case.  */
+  if (call->expr_type == EXPR_FUNCTION)
+    return call->value.function.isym;
+  else
+    return NULL;
+}
+
+
+/* Indicates whether an argument to an intrinsic function should be used in
+   scalarization.  It is usually the case, except for some intrinsics
+   requiring the value to be constant, and using the value at compile time only.
+   As the value is not used at runtime in those cases, we don’t produce code
+   for it, and it should not be visible to the scalarizer.  */
+
+static bool
+arg_evaluated_for_scalarization (gfc_intrinsic_sym *function,
+				 gfc_dummy_arg *dummy_arg)
+{
+  if (function != NULL && dummy_arg != NULL)
+    {
+      switch (function->id)
+	{
+	  case GFC_ISYM_INDEX:
+	    if (strcmp ("kind", gfc_dummy_arg_get_name (*dummy_arg)) == 0)
+	      return false;
+	  /* Fallthrough.  */
+
+	  default:
+	    break;
+	}
+    }
+
+  return true;
+}
+
+
 /* Walk the arguments of an elemental function.
    PROC_EXPR is used to check whether an argument is permitted to be absent.  If
    it is NULL, we don't do the check and the argument is assumed to be present.
@@ -11208,6 +11253,7 @@ gfc_get_proc_ifc_for_expr (gfc_expr *procedure_ref)
 
 gfc_ss *
 gfc_walk_elemental_function_args (gfc_ss * ss, gfc_actual_arglist *arg,
+				  gfc_intrinsic_sym *intrinsic_sym,
 				  gfc_ss_type type)
 {
   int scalar;
@@ -11222,7 +11268,9 @@ gfc_walk_elemental_function_args (gfc_ss * ss, gfc_actual_arglist *arg,
   for (; arg; arg = arg->next)
     {
       gfc_dummy_arg * const dummy_arg = arg->associated_dummy;
-      if (!arg->expr || arg->expr->expr_type == EXPR_NULL)
+      if (!arg->expr
+	  || arg->expr->expr_type == EXPR_NULL
+	  || !arg_evaluated_for_scalarization (intrinsic_sym, dummy_arg))
 	continue;
 
       newss = gfc_walk_subexpr (head, arg->expr);
@@ -11311,6 +11359,7 @@ gfc_walk_function_expr (gfc_ss * ss, gfc_expr * expr)
 
       ss = gfc_walk_elemental_function_args (old_ss,
 					     expr->value.function.actual,
+					     gfc_get_intrinsic_for_expr (expr),
 					     GFC_SS_REFERENCE);
       if (ss != old_ss
 	  && (comp
diff --git a/gcc/fortran/trans-array.h b/gcc/fortran/trans-array.h
index 998fd284dd6..19c2f765b9a 100644
--- a/gcc/fortran/trans-array.h
+++ b/gcc/fortran/trans-array.h
@@ -74,6 +74,8 @@ void gfc_trans_static_array_pointer (gfc_symbol *);
 
 /* Get the procedure interface for a function call.  */
 gfc_symbol *gfc_get_proc_ifc_for_expr (gfc_expr *);
+/* Get the intrinsic symbol for an intrinsic function call.  */
+gfc_intrinsic_sym *gfc_get_intrinsic_for_expr (gfc_expr *);
 /* Generate scalarization information for an expression.  */
 gfc_ss *gfc_walk_expr (gfc_expr *);
 /* Workhorse for gfc_walk_expr.  */
@@ -82,6 +84,7 @@ gfc_ss *gfc_walk_subexpr (gfc_ss *, gfc_expr *);
 gfc_ss *gfc_walk_array_ref (gfc_ss *, gfc_expr *, gfc_ref * ref);
 /* Walk the arguments of an elemental function.  */
 gfc_ss *gfc_walk_elemental_function_args (gfc_ss *, gfc_actual_arglist *,
+					  gfc_intrinsic_sym *,
 					  gfc_ss_type);
 /* Walk an intrinsic function.  */
 gfc_ss *gfc_walk_intrinsic_function (gfc_ss *, gfc_expr *,
diff --git a/gcc/fortran/trans-intrinsic.c b/gcc/fortran/trans-intrinsic.c
index 8a9283b358d..c2383119e5d 100644
--- a/gcc/fortran/trans-intrinsic.c
+++ b/gcc/fortran/trans-intrinsic.c
@@ -11163,6 +11163,7 @@ gfc_walk_intrinsic_function (gfc_ss * ss, gfc_expr * expr,
 
   if (isym->elemental)
     return gfc_walk_elemental_function_args (ss, expr->value.function.actual,
+					     expr->value.function.isym,
 					     GFC_SS_SCALAR);
 
   if (expr->rank == 0)
diff --git a/gcc/fortran/trans-stmt.c b/gcc/fortran/trans-stmt.c
index 3fd4475f411..2b9ca875ee5 100644
--- a/gcc/fortran/trans-stmt.c
+++ b/gcc/fortran/trans-stmt.c
@@ -356,6 +356,25 @@ gfc_conv_elemental_dependencies (gfc_se * se, gfc_se * loopse,
 }
 
 
+/* Given an executable statement referring to an intrinsic function call,
+   returns the intrinsic symbol.  */
+
+static gfc_intrinsic_sym *
+get_intrinsic_for_code (gfc_code *code)
+{
+  if (code->op == EXEC_CALL)
+    {
+      gfc_intrinsic_sym * const isym = code->resolved_isym;
+      if (isym)
+	return isym;
+      else
+	return gfc_get_intrinsic_for_expr (code->expr1);
+    }
+
+  return NULL;
+}
+
+
 /* Translate the CALL statement.  Builds a call to an F95 subroutine.  */
 
 tree
@@ -381,6 +400,7 @@ gfc_trans_call (gfc_code * code, bool dependency_check,
   ss = gfc_ss_terminator;
   if (code->resolved_sym->attr.elemental)
     ss = gfc_walk_elemental_function_args (ss, code->ext.actual,
+					   get_intrinsic_for_code (code),
 					   GFC_SS_REFERENCE);
 
   /* MVBITS is inlined but needs the dependency checking found here.  */
diff --git a/gcc/testsuite/gfortran.dg/index_5.f90 b/gcc/testsuite/gfortran.dg/index_5.f90
new file mode 100644
index 00000000000..e039455d175
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/index_5.f90
@@ -0,0 +1,23 @@
+! { dg-do compile }
+!
+! PR fortran/97896
+! An ICE occured with INDEX when the KIND argument was present
+! because of a mismatch between the number of arguments expected
+! during the scalarization process and the number of arguments actually
+! used.
+!
+! Test contributed by Harald Anlauf <anlauf@gcc.gnu.org>, based on an initial
+! submission by G. Steinmetz <gscfq@t-online.de>.
+
+program p
+  implicit none
+  logical    :: a(2)
+  integer    :: b(2)
+  integer(8) :: d(2)
+  b = index ('xyxyz','yx', back=a)
+  b = index ('xyxyz','yx', back=a, kind=4)
+  d = index ('xyxyz','yx', back=a, kind=8)
+  b = index ('xyxyz','yx', back=a, kind=8)
+  d = index ('xyxyz','yx', back=a, kind=4)
+end
+