PR middle-end/83688 - check if buffers may overlap when copying strings using sprintf

gcc/ChangeLog:

	PR middle-end/83688
	* gimple-ssa-sprintf.c (format_result::alias_info): New struct.
	(directive::argno): New member.
	(format_result::aliases, format_result::alias_count): New data members.
	(format_result::append_alias): New member function.
	(fmtresult::dst_offset): New data member.
	(pass_sprintf_length::call_info::dst_origin): New data member.
	(pass_sprintf_length::call_info::dst_field, dst_offset): Same.
	(char_type_p, array_elt_at_offset, field_at_offset): New functions.
	(get_origin_and_offset): Same.
	(format_string): Call it.
	(format_directive): Call append_alias and set directive argument
	number.
	(maybe_warn_overlap): New function.
	(pass_sprintf_length::compute_format_length): Call it.
	(pass_sprintf_length::handle_gimple_call): Initialize new members.
	* gcc/tree-ssa-strlen.c (): Also enable when -Wrestrict is on.

gcc/testsuite/ChangeLog:

	PR tree-optimization/35503
	* gcc.dg/tree-ssa/builtin-sprintf-warn-23.c: New test.

From-SVN: r278098

gcc/ChangeLog

+2019-11-12  Martin Sebor  <msebor@redhat.com>
+
+	PR middle-end/83688
+	* gimple-ssa-sprintf.c (format_result::alias_info): New struct.
+	(directive::argno): New member.
+	(format_result::aliases, format_result::alias_count): New data members.
+	(format_result::append_alias): New member function.
+	(fmtresult::dst_offset): New data member.
+	(pass_sprintf_length::call_info::dst_origin): New data member.
+	(pass_sprintf_length::call_info::dst_field, dst_offset): Same.
+	(char_type_p, array_elt_at_offset, field_at_offset): New functions.
+	(get_origin_and_offset): Same.
+	(format_string): Call it.
+	(format_directive): Call append_alias and set directive argument
+	number.
+	(maybe_warn_overlap): New function.
+	(pass_sprintf_length::compute_format_length): Call it.
+	(pass_sprintf_length::handle_gimple_call): Initialize new members.
+	* gcc/tree-ssa-strlen.c (): Also enable when -Wrestrict is on.
+
 2019-11-12  Ilya Leoshkevich  <iii@linux.ibm.com>
 
 	PR rtl-optimization/92430

gcc/testsuite/ChangeLog

+2019-11-12  Martin Sebor  <msebor@redhat.com>
+
+	PR tree-optimization/35503
+	* gcc.dg/tree-ssa/builtin-sprintf-warn-23.c: New test.
+
 2019-11-12  Nathan Sidwell  <nathan@acm.org>
 
 	* g++.dg/lookup/pr6936.C: Delete, identical to using38.C

gcc/tree-ssa-strlen.c

@@ -5344,6 +5344,7 @@ pass_strlen::gate (function *)
 {
   return ((warn_format_overflow > 0
 	   || warn_format_trunc > 0
+	   || warn_restrict > 0
 	   || flag_optimize_strlen > 0
 	   || flag_printf_return_value)
 	  && optimize > 0);