This patch extends -fdump-analyzer-supergraph so that rather than just
dumping a DUMP_BASE_NAME.supergraph.dot at the start of analysis, it
also dumps a DUMP_BASE_NAME.supergraph-eg.dot at the end.

The new dump file contains a concise dump of the exploded_graph,
organized with respect to the supergraph and its statements.  The
exploded nodes are colorized to show sm-state, but no other state
is shown.  Per exploded_node saved_diagnostics are also shown,
along with feasibility of the paths to reach them.

I've been finding this a useful way of tracking down issues in
exploded_graphs that are sufficiently large that the output of
-fdump-analyzer-exploded-graph becomes unwieldy.

The patch extends feasiblity-testing so that if the exploded_path
for a saved_diagnostic is found to be infeasible, the reason is
saved and written into the saved_diagnostic, so it can be shown in the
dump.  I've found this very useful when tracking down feasibility
issues.

I'm keeping the initial dump file as it's useful when tracking down
ICEs within the analyzer (which would stop the second dump file being
written).

gcc/analyzer/ChangeLog:
	* analyzer.h (class feasibility_problem): New forward decl.
	* diagnostic-manager.cc (saved_diagnostic::saved_diagnostic):
	Initialize new fields m_status, m_epath_length, and m_problem.
	(saved_diagnostic::~saved_diagnostic): Delete m_problem.
	(dedupe_candidate::dedupe_candidate): Convert "sd" param from a
	const ref to a mutable ptr.
	(dedupe_winners::add): Convert "sd" param from a const ref to a
	mutable ptr.  Record the length of the exploded_path.  Record the
	feasibility/infeasibility of sd into sd, capturing a
	feasibility_problem when feasible_p fails, and storing it in sd.
	(diagnostic_manager::emit_saved_diagnostics): Update for pass by
	ptr rather than by const ref.
	* diagnostic-manager.h (class saved_diagnostic): Add new enum
	status.  Add fields m_status, m_epath_length and m_problem.
	(saved_diagnostic::set_feasible): New member function.
	(saved_diagnostic::set_infeasible): New member function.
	(saved_diagnostic::get_feasibility_problem): New accessor.
	(saved_diagnostic::get_status): New accessor.
	(saved_diagnostic::set_epath_length): New member function.
	(saved_diagnostic::get_epath_length): New accessor.
	* engine.cc: Include "gimple-pretty-print.h".
	(exploded_path::feasible_p): Add OUT param and, if non-NULL, write
	a new feasibility_problem to it on failure.
	(viz_callgraph_node::dump_dot): Convert begin_tr calls to
	begin_trtd.  Convert end_tr calls to end_tdtr.
	(class exploded_graph_annotator): New subclass of dot_annotator.
	(impl_run_checkers): Add a second -fdump-analyzer-supergraph dump
	after the analysis runs, using exploded_graph_annotator. dumping
	to DUMP_BASE_NAME.supergraph-eg.dot.
	* exploded-graph.h (exploded_node::get_dot_fillcolor): Make
	public.
	(exploded_path::feasible_p): Add OUT param.
	(class feasibility_problem): New class.
	* state-purge.cc (state_purge_annotator::add_node_annotations):
	Return a bool, add a "within_table" param.
	(print_vec_of_names): Convert begin_tr calls to begin_trtd.
	Convert end_tr calls to end_tdtr.
	(state_purge_annotator::add_stmt_annotations): Add "within_row"
	param.
	* state-purge.h ((state_purge_annotator::add_node_annotations):
	Return a bool, add a "within_table" param.
	(state_purge_annotator::add_stmt_annotations): Add "within_row"
	param.
	* supergraph.cc (supernode::dump_dot): Call add_node_annotations
	twice: as before, passing false for "within_table", then again
	with true when within the TABLE element.  Convert some begin_tr
	calls to begin_trtd, and some end_tr calls to end_tdtr.
	Repeat each add_stmt_annotations call, distinguishing between
	calls that add TRs and those that add TDs to an existing TR.
	Add a call to add_after_node_annotations.
	* supergraph.h (dot_annotator::add_node_annotations): Add a
	"within_table" param.
	(dot_annotator::add_stmt_annotations): Add a "within_row" param.
	(dot_annotator::add_after_node_annotations): New vfunc.

gcc/ChangeLog:
	* doc/invoke.texi (-fdump-analyzer-supergraph): Document that this
	now emits two .dot files.
	* graphviz.cc (graphviz_out::begin_tr): Only emit a TR, not a TD.
	(graphviz_out::end_tr): Only close a TR, not a TD.
	(graphviz_out::begin_td): New.
	(graphviz_out::end_td): New.
	(graphviz_out::begin_trtd): New, replacing the old implementation
	of graphviz_out::begin_tr.
	(graphviz_out::end_tdtr): New, replacing the old implementation
	of graphviz_out::end_tr.
	* graphviz.h (graphviz_out::begin_td): New decl.
	(graphviz_out::end_td): New decl.
	(graphviz_out::begin_trtd): New decl.
	(graphviz_out::end_tdtr): New decl.

gcc/testsuite/ChangeLog:
	* gcc.dg/analyzer/dot-output.c: Check that
	dot-output.c.supergraph-eg.dot is valid.