[gcc r12-7811] fortran: Fix up initializers of param(0) PARAMETERs [PR103691]

[gcc r12-7811] fortran: Fix up initializers of param(0) PARAMETERs [PR103691]

[Jakub Jelinek]

https://gcc.gnu.org/g:45e955b0a936eafc9838cdc00dcc31b3799b321b

commit r12-7811-g45e955b0a936eafc9838cdc00dcc31b3799b321b
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Mar 25 11:22:15 2022 +0100

    fortran: Fix up initializers of param(0) PARAMETERs [PR103691]
    
    On the gfortran.dg/pr103691.f90 testcase the Fortran ICE emits
      static real(kind=4) a[0] = {[0 ... -1]=2.0e+0};
    That is an invalid RANGE_EXPR where the maximum is smaller than the minimum.
    
    The following patch fixes that.  If TYPE_MAX_VALUE is smaller than
    TYPE_MIN_VALUE, the array is empty and so doesn't need any initializer,
    if the two are equal, we don't need to bother with a RANGE_EXPR and
    can just use that INTEGER_CST as the index and finally for the 2+ values
    in the range it uses a RANGE_EXPR as before.
    
    2022-03-25  Jakub Jelinek  <jakub@redhat.com>
    
            PR fortran/103691
            * trans-array.cc (gfc_conv_array_initializer): If TYPE_MAX_VALUE is
            smaller than TYPE_MIN_VALUE (i.e. empty array), ignore the
            initializer; if TYPE_MIN_VALUE is equal to TYPE_MAX_VALUE, use just
            the TYPE_MIN_VALUE as index instead of RANGE_EXPR.

Diff:
---
 gcc/fortran/trans-array.cc | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index cfb6eac11c7..b3f8871ff22 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -6267,10 +6267,17 @@ gfc_conv_array_initializer (tree type, gfc_expr * expr)
       else
 	gfc_conv_structure (&se, expr, 1);
 
-      CONSTRUCTOR_APPEND_ELT (v, build2 (RANGE_EXPR, gfc_array_index_type,
-					 TYPE_MIN_VALUE (TYPE_DOMAIN (type)),
-					 TYPE_MAX_VALUE (TYPE_DOMAIN (type))),
-			      se.expr);
+      if (tree_int_cst_lt (TYPE_MAX_VALUE (TYPE_DOMAIN (type)),
+			   TYPE_MIN_VALUE (TYPE_DOMAIN (type))))
+	break;
+      else if (tree_int_cst_equal (TYPE_MIN_VALUE (TYPE_DOMAIN (type)),
+				   TYPE_MAX_VALUE (TYPE_DOMAIN (type))))
+	range = TYPE_MIN_VALUE (TYPE_DOMAIN (type));
+      else
+	range = build2 (RANGE_EXPR, gfc_array_index_type,
+			TYPE_MIN_VALUE (TYPE_DOMAIN (type)),
+			TYPE_MAX_VALUE (TYPE_DOMAIN (type)));
+      CONSTRUCTOR_APPEND_ELT (v, range, se.expr);
       break;
 
     case EXPR_ARRAY: