Re: [patch v2] Fortran: fix sm computation in CFI_allocate [PR93524]

[Sandra Loosemore <sandra@codesourcery.com>]

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On 6/21/21 5:42 AM, Tobias Burnus wrote:
> On 21.06.21 08:05, Sandra Loosemore wrote:
> 
>> I ran into this bug in CFI_allocate while testing something else and 
>> then realized there was already a PR open for it.  It seems like an 
>> easy fix, and I've used Tobias's test case from the issue more or less 
>> verbatim.
>>
>> There were some other bugs added on to this issue but I think they 
>> have all been fixed already except for this one.
>>
>> OK to check in?
> OK – but see some comments below.

Revised patch attached.  How's this one?

-Sandra

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commit 323fda07729fa0b0f2d1f8b4269db874280ac318
Author: Sandra Loosemore <sandra@codesourcery.com>
Date:   Mon Jun 21 13:25:55 2021 -0700

    Fortran: fix sm computation in CFI_allocate [PR93524]
    
    This patch fixes a bug in setting the step multiplier field in the
    C descriptor for array dimensions > 2.
    
    2021-06-21  Sandra Loosemore  <sandra@codesourcery.com>
                Tobias Burnus  <tobias@codesourcery.com>
    
    libgfortran/
    	PR fortran/93524
    	* runtime/ISO_Fortran_binding.c (CFI_allocate): Fix
    	sm computation.
    
    gcc/testsuite/
    	PR fortran/93524
    	* gfortran.dg/pr93524.c: New.
    	* gfortran.dg/pr93524.f90: New.

diff --git a/gcc/testsuite/gfortran.dg/pr93524.c b/gcc/testsuite/gfortran.dg/pr93524.c
new file mode 100644
index 0000000..24e5e09
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr93524.c
@@ -0,0 +1,33 @@
+/* Test the fix for PR93524, in which CFI_allocate was computing
+   sm incorrectly for dimensions > 2.  */
+
+#include <stdlib.h>  // For size_t
+#include "../../../libgfortran/ISO_Fortran_binding.h"
+
+void my_fortran_sub_1 (CFI_cdesc_t *dv); 
+void my_fortran_sub_2 (CFI_cdesc_t *dv); 
+
+int main ()
+{
+  CFI_CDESC_T (3) a;
+  CFI_cdesc_t *dv = (CFI_cdesc_t *) &a;
+  // dv, base_addr, attribute,            type, elem_len, rank, extents
+  CFI_establish (dv, NULL, CFI_attribute_allocatable, CFI_type_float, 0, 3, NULL); 
+
+  if (dv->base_addr != NULL)
+    return 1;  // shall not be allocated
+
+  CFI_index_t lower_bounds[] = {-10, 0, 3}; 
+  CFI_index_t upper_bounds[] = {10, 5, 10}; 
+  size_t elem_len = 0;  // only needed for strings
+  if (CFI_SUCCESS != CFI_allocate (dv, lower_bounds, upper_bounds, elem_len))
+    return 2;
+
+  if (!CFI_is_contiguous (dv))
+    return 2;  // allocatables shall be contiguous,unless a strided section is used
+
+  my_fortran_sub_1 (dv);
+  my_fortran_sub_2 (dv);
+  CFI_deallocate (dv);
+  return 0;
+}
diff --git a/gcc/testsuite/gfortran.dg/pr93524.f90 b/gcc/testsuite/gfortran.dg/pr93524.f90
new file mode 100644
index 0000000..0cebc8f
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr93524.f90
@@ -0,0 +1,17 @@
+! { dg-additional-sources pr93524.c }
+! { dg-do run }
+!
+! Test the fix for PR93524.  The main program is in pr93524.c.
+
+subroutine my_fortran_sub_1 (A) bind(C)
+  real :: A(:, :, :)
+  if (any (lbound(A) /= 1)) stop 1
+  if (any (ubound(A) /= [21,6,8])) stop 2
+  if (.not. is_contiguous (A)) stop 3
+end
+subroutine my_fortran_sub_2 (A) bind(C)
+  real, ALLOCATABLE :: A(:, :, :)
+  if (any (lbound(A) /= [-10,0,3])) stop 1
+  if (any (ubound(A) /= [10,5,10])) stop 2
+  if (.not. is_contiguous (A)) stop 3
+end subroutine my_fortran_sub_2
diff --git a/libgfortran/runtime/ISO_Fortran_binding.c b/libgfortran/runtime/ISO_Fortran_binding.c
index 20833ad..0978832 100644
--- a/libgfortran/runtime/ISO_Fortran_binding.c
+++ b/libgfortran/runtime/ISO_Fortran_binding.c
@@ -254,10 +254,7 @@ CFI_allocate (CFI_cdesc_t *dv, const CFI_index_t lower_bounds[],
 	{
 	  dv->dim[i].lower_bound = lower_bounds[i];
 	  dv->dim[i].extent = upper_bounds[i] - dv->dim[i].lower_bound + 1;
-	  if (i == 0)
-	    dv->dim[i].sm = dv->elem_len;
-	  else
-	    dv->dim[i].sm = dv->elem_len * dv->dim[i - 1].extent;
+	  dv->dim[i].sm = dv->elem_len * arr_len;
 	  arr_len *= dv->dim[i].extent;
         }
     }