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Build a zero element array type that reliably renders as T[0] in diagnostcs.

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gcc/ChangeLog:

	* gimple-array-bounds.cc (build_zero_elt_array_type): New function.
	(array_bounds_checker::check_mem_ref): Call it.
This commit is contained in:
Martin Sebor 2020-09-23 15:19:13 -06:00
parent 6edc8f5bfe
commit 67aeddb785
1 changed files with 18 additions and 1 deletions
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19
gcc/gimple-array-bounds.cc
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@ -372,6 +372,20 @@ array_bounds_checker::check_array_ref (location_t location, tree ref,
return warned;
}
/* Hack around the internal representation constraints and build a zero
element array type that actually renders as T[0] in diagnostcs. */
static tree
build_zero_elt_array_type (tree eltype)
{
tree idxtype = build_range_type (sizetype, size_zero_node, NULL_TREE);
tree arrtype = build_array_type (eltype, idxtype);
arrtype = build_distinct_type_copy (TYPE_MAIN_VARIANT (arrtype));
TYPE_SIZE (arrtype) = bitsize_zero_node;
TYPE_SIZE_UNIT (arrtype) = size_zero_node;
return arrtype;
}
/* Checks one MEM_REF in REF, located at LOCATION, for out-of-bounds
references to string constants. If VRP can determine that the array
subscript is a constant, check if it is outside valid range.
@ -547,7 +561,10 @@ array_bounds_checker::check_mem_ref (location_t location, tree ref,
return false;
offset_int nelts = arrbounds[1] / eltsize;
reftype = build_array_type_nelts (reftype, nelts.to_uhwi ());
if (nelts == 0)
reftype = build_zero_elt_array_type (reftype);
else
reftype = build_array_type_nelts (reftype, nelts.to_uhwi ());
}
else if (TREE_CODE (arg) == ADDR_EXPR)
{