analyzer: fix uninit false +ves [PR108664,PR108666,PR108725]

This patch updates poisoned_value_diagnostic so that, where possible,
it checks to see if the value is still poisoned along the execution
path seen during feasibility analysis, rather than just that seen
in the exploded graph.

Integration testing shows this reduction in the number of
false positives:
  -Wanalyzer-use-of-uninitialized-value: 191 -> 153 (-38)
where the changes happen in:
      coreutils-9.1: 34 -> 20 (-14)
         qemu-7.2.0: 78 -> 54 (-24)

gcc/analyzer/ChangeLog:
	PR analyzer/108664
	PR analyzer/108666
	PR analyzer/108725
	* diagnostic-manager.cc (epath_finder::get_best_epath): Add
	"target_stmt" param.
	(epath_finder::explore_feasible_paths): Likewise.
	(epath_finder::process_worklist_item): Likewise.
	(saved_diagnostic::calc_best_epath): Pass m_stmt to
	epath_finder::get_best_epath.
	* engine.cc (feasibility_state::maybe_update_for_edge): Move
	per-stmt logic to...
	(feasibility_state::update_for_stmt): ...this new function.
	* exploded-graph.h (feasibility_state::update_for_stmt): New decl.
	* feasible-graph.cc (feasible_node::get_state_at_stmt): New.
	* feasible-graph.h: Include "analyzer/exploded-graph.h".
	(feasible_node::get_state_at_stmt): New decl.
	* infinite-recursion.cc
	(infinite_recursion_diagnostic::check_valid_fpath_p): Update for
	vfunc signature change.
	* pending-diagnostic.h (pending_diagnostic::check_valid_fpath_p):
	Convert first param to a reference.  Add stmt param.
	* region-model.cc: Include "analyzer/feasible-graph.h".
	(poisoned_value_diagnostic::poisoned_value_diagnostic): Add
	"check_expr" param.
	(poisoned_value_diagnostic::check_valid_fpath_p): New.
	(poisoned_value_diagnostic::m_check_expr): New field.
	(region_model::check_for_poison): Attempt to supply a check_expr
	to the diagnostic
	(region_model::deref_rvalue): Add NULL for new check_expr param
	of poisoned_value_diagnostic.
	(region_model::get_or_create_region_for_heap_alloc): Don't reuse
	regions that are marked as TOUCHED.

gcc/testsuite/ChangeLog:
	PR analyzer/108664
	PR analyzer/108666
	PR analyzer/108725
	* gcc.dg/analyzer/coreutils-cksum-pr108664.c: New test.
	* gcc.dg/analyzer/coreutils-sum-pr108666.c: New test.
	* gcc.dg/analyzer/torture/uninit-pr108725.c: New test.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/gcc/analyzer/infinite-recursion.cc b/gcc/analyzer/infinite-recursion.cc
index 8d101d1..1886534 100644
--- a/gcc/analyzer/infinite-recursion.cc
+++ b/gcc/analyzer/infinite-recursion.cc
@@ -203,18 +203,19 @@ public:
   /* Reject paths in which conjured svalues have affected control flow
      since m_prev_entry_enode.  */
 
-  bool check_valid_fpath_p (const feasible_node *final_fnode)
+  bool check_valid_fpath_p (const feasible_node &final_fnode,
+			    const gimple *)
     const final override
   {
     /* Reject paths in which calls with unknown side effects have occurred
        since m_prev_entry_enode.
        Find num calls with side effects.  Walk backward until we reach the
        pref */
-    gcc_assert (final_fnode->get_inner_node () == m_new_entry_enode);
+    gcc_assert (final_fnode.get_inner_node () == m_new_entry_enode);
 
     /* FG is actually a tree.  Walk backwards from FINAL_FNODE until we
        reach the prev_entry_enode (or the origin).  */
-    const feasible_node *iter_fnode = final_fnode;
+    const feasible_node *iter_fnode = &final_fnode;
     while (iter_fnode->get_inner_node ()->m_index != 0)
       {
 	gcc_assert (iter_fnode->m_preds.length () == 1);