The -Warray-bounds enhancement I added to GCC 9 causes false
positives in languages like Fortran whose first array element
is at a non-zero index. The attached patch has the function
responsible for the warning normalize the array bounds to
always start at zero to avoid these false positives.
Tested on x86_64-linux.
Martin
PR middle-end/91584 - Bogus warning from -Warray-bounds during string assignment
gcc/ChangeLog:
PR middle-end/91584
* tree-vrp.c (vrp_prop::check_mem_ref): Normalize type domain bounds
before using them to validate MEM_REF offset.
gcc/testsuite/ChangeLog:
* gfortran.dg/char_array_constructor_4.f90: New test.
Index: gcc/tree-vrp.c
===================================================================
--- gcc/tree-vrp.c (revision 275047)
+++ gcc/tree-vrp.c (working copy)
@@ -4703,31 +4703,23 @@ vrp_prop::check_mem_ref (location_t location, tree
|| RECORD_OR_UNION_TYPE_P (reftype))
return false;
+ arrbounds[0] = 0;
+
offset_int eltsize;
if (TREE_CODE (reftype) == ARRAY_TYPE)
{
eltsize = wi::to_offset (TYPE_SIZE_UNIT (TREE_TYPE (reftype)));
-
if (tree dom = TYPE_DOMAIN (reftype))
{
tree bnds[] = { TYPE_MIN_VALUE (dom), TYPE_MAX_VALUE (dom) };
- if (array_at_struct_end_p (arg)
- || !bnds[0] || !bnds[1])
- {
- arrbounds[0] = 0;
- arrbounds[1] = wi::lrshift (maxobjsize, wi::floor_log2 (eltsize));
- }
+ if (array_at_struct_end_p (arg) || !bnds[0] || !bnds[1])
+ arrbounds[1] = wi::lrshift (maxobjsize, wi::floor_log2 (eltsize));
else
- {
- arrbounds[0] = wi::to_offset (bnds[0]) * eltsize;
- arrbounds[1] = (wi::to_offset (bnds[1]) + 1) * eltsize;
- }
+ arrbounds[1] = (wi::to_offset (bnds[1]) - wi::to_offset (bnds[0])
+ + 1) * eltsize;
}
else
- {
- arrbounds[0] = 0;
- arrbounds[1] = wi::lrshift (maxobjsize, wi::floor_log2 (eltsize));
- }
+ arrbounds[1] = wi::lrshift (maxobjsize, wi::floor_log2 (eltsize));
if (TREE_CODE (ref) == MEM_REF)
{
@@ -4742,7 +4734,6 @@ vrp_prop::check_mem_ref (location_t location, tree
else
{
eltsize = 1;
- arrbounds[0] = 0;
arrbounds[1] = wi::to_offset (TYPE_SIZE_UNIT (reftype));
}
Index: gcc/testsuite/gfortran.dg/char_array_constructor_4.f90
===================================================================
--- gcc/testsuite/gfortran.dg/char_array_constructor_4.f90 (nonexistent)
+++ gcc/testsuite/gfortran.dg/char_array_constructor_4.f90 (working copy)
@@ -0,0 +1,13 @@
+! PR 30319 - Bogus warning from -Warray-bounds during string assignment
+! { dg-do compile }
+! { dg-options "-O2 -Warray-bounds" }
+
+program test_bounds
+
+ character(256) :: foo
+
+ foo = '1234' ! { dg-bogus "\\\[-Warray-bounds" }
+
+ print *, foo
+
+end program test_bounds
