[gcc(refs/users/mikael/heads/refactor_descriptor_v206.01)] fortran: array descriptor: Simplify scalar dtype initialization [PR122521]

https://gcc.gnu.org/g:4b7eaf7f5b57e224afba0e106bb015b8d831e210

commit 4b7eaf7f5b57e224afba0e106bb015b8d831e210
Author: Mikael Morin <[email protected]>
Date:   Tue Aug 18 14:19:32 2026 +0200

    fortran: array descriptor: Simplify scalar dtype initialization [PR122521]
    
    Fortran-tested on aarch64-unknown-linux-gnu.  OK for mainline?
    
    -- >8 --
    
    The function gfc_set_descriptor_from_scalar creates a new scalar descriptor
    type that is only used as argument to gfc_get_dtype, to get the dtype
    initialization value.  gfc_get_dtype extracts two pieces of information from
    that descriptor type: the rank, and the element type.  As the rank is known
    to be zero, and the element type was part of the input to create the
    descriptor type, we can avoid the roundtrip through the descriptor type
    creation, and use directly the zero rank and the element type.  This change
    does that.  It permits the removal of one argument from
    gfc_set_descriptor_from_scalar.
    
    With the call to the descriptor type creation function removed, the pointer
    unwrapping of the element type the function was doing is removed as well.
    Add it back to the gfc_set_descriptor_from_scalar code.
    
            PR fortran/122521
    
    gcc/fortran/ChangeLog:
    
            * trans-descriptor.h (gfc_set_descriptor_from_scalar,
            gfc_set_descriptor_from_scalar_class): Remove expression argument.
            * trans-descriptor.cc (gfc_set_descriptor_from_scalar_class):
            (gfc_set_descriptor_from_scalar): Ditto.  Explicitly unwrap element
            type if it's pointer-typed.  Use gfc_get_dtype_rank_type instead of
            gfc_get_dtype.  Remove scalar descriptor type creation.
            * trans-expr.cc (gfc_conv_derived_to_class,
            gfc_conv_class_to_class): Update callers.

Diff:
---
 gcc/fortran/trans-descriptor.cc | 16 ++++++++--------
 gcc/fortran/trans-descriptor.h  |  5 ++---
 gcc/fortran/trans-expr.cc       |  4 ++--
 3 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/gcc/fortran/trans-descriptor.cc b/gcc/fortran/trans-descriptor.cc
index 534e9fe88dc8..f6af3d2a8cfc 100644
--- a/gcc/fortran/trans-descriptor.cc
+++ b/gcc/fortran/trans-descriptor.cc
@@ -858,17 +858,18 @@ gfc_create_null_actual_descriptor (stmtblock_t *block, gfc_typespec *ts,
    assumed-rank dummy argument.  */
 
 void
-gfc_set_descriptor_from_scalar (stmtblock_t *block, tree descr,
-				tree scalar, gfc_expr *scalar_expr,
+gfc_set_descriptor_from_scalar (stmtblock_t *block, tree descr, tree scalar,
 				tree cond_presence, tree caf_token)
 {
   if (flag_coarray == GFC_FCOARRAY_LIB && caf_token)
     gfc_conv_descriptor_token_set (block, descr, caf_token);
 
-  tree type = gfc_get_scalar_to_descriptor_type (TREE_TYPE (scalar),
-						 gfc_expr_attr (scalar_expr));
+  tree scalar_type = TREE_TYPE (scalar);
+  tree etype = POINTER_TYPE_P (scalar_type)
+	       ? TREE_TYPE (scalar_type)
+	       : scalar_type;
   gfc_conv_descriptor_dtype_set (block, descr,
-				 gfc_get_dtype (type));
+				 gfc_get_dtype_rank_type (0, etype));
   gfc_copy_coarray_desc_part (block, descr, scalar);
   if (cond_presence)
     scalar = build3_loc (input_location, COND_EXPR,
@@ -910,11 +911,10 @@ gfc_set_descriptor_from_scalar (stmtblock_t *block, tree descr, tree scalar)
 
 void
 gfc_set_descriptor_from_scalar_class (stmtblock_t *block, tree descr,
-				      tree scalar, gfc_expr *scalar_expr)
+				      tree scalar)
 {
   tree tmp = gfc_class_data_get (scalar);
-  gfc_set_descriptor_from_scalar (block, descr, tmp, scalar_expr, NULL_TREE,
-				  NULL_TREE);
+  gfc_set_descriptor_from_scalar (block, descr, tmp, NULL_TREE, NULL_TREE);
 }
 
 
diff --git a/gcc/fortran/trans-descriptor.h b/gcc/fortran/trans-descriptor.h
index 2154411602da..9ccae12e11c6 100644
--- a/gcc/fortran/trans-descriptor.h
+++ b/gcc/fortran/trans-descriptor.h
@@ -73,10 +73,9 @@ tree gfc_create_unallocated_library_result_descriptor (stmtblock_t *, tree,
 tree gfc_create_null_actual_descriptor (stmtblock_t *, gfc_typespec *,
 					symbol_attribute, int);
 
-void gfc_set_descriptor_from_scalar (stmtblock_t *, tree, tree, gfc_expr *,
-				     tree, tree);
+void gfc_set_descriptor_from_scalar (stmtblock_t *, tree, tree, tree, tree);
 void gfc_set_descriptor_from_scalar (stmtblock_t *, tree, tree);
-void gfc_set_descriptor_from_scalar_class (stmtblock_t *, tree, tree, gfc_expr *);
+void gfc_set_descriptor_from_scalar_class (stmtblock_t *, tree, tree);
 
 tree gfc_conv_descriptor_size (tree, int);
 tree gfc_conv_descriptor_cosize (tree, int, int);
diff --git a/gcc/fortran/trans-expr.cc b/gcc/fortran/trans-expr.cc
index 7338cf2b97ff..84da2aa600c6 100644
--- a/gcc/fortran/trans-expr.cc
+++ b/gcc/fortran/trans-expr.cc
@@ -896,7 +896,7 @@ gfc_conv_derived_to_class (gfc_se *parmse, gfc_expr *e, gfc_symbol *fsym,
 	  /* Scalar to an assumed-rank array.  */
 	  if (fsym->ts.u.derived->components->as)
 	    gfc_set_descriptor_from_scalar (&parmse->pre, ctree, parmse->expr,
-					    e, cond_optional, caf_token);
+					    cond_optional, caf_token);
           else
 	    {
 	      tmp = fold_convert (TREE_TYPE (ctree), parmse->expr);
@@ -1324,7 +1324,7 @@ gfc_conv_class_to_class (gfc_se *parmse, gfc_expr *e, gfc_typespec class_ts,
       && e->rank != class_ts.u.derived->components->as->rank)
     {
       if (e->rank == 0)
-	gfc_set_descriptor_from_scalar_class (&block, ctree, parmse->expr, e);
+	gfc_set_descriptor_from_scalar_class (&block, ctree, parmse->expr);
       else
 	gfc_class_array_data_assign (&block, ctree, parmse->expr, false);
     }