analyzer: fix false leak involving params [PR98969]

This patch updates the svalue liveness code so that the initial value
of parameters at top-level functions to the analysis are treated as
live (since the values are presumably still live within the
outside-of-the-analysis calling code).

This fixes the false leak in PR analyzer/98969 seen on:

void
test (long int i)
{
  struct foo *f = (struct foo *)i;
  f->expr = __builtin_malloc (1024);
}

since the calling code can presumably still access the allocated
buffer via:
  ((struct foo *)i)->expr

The patch also removes the expected leak warnings from
g++.dg/analyzer/pr99064.C and gcc.dg/analyzer/pr96841.c, which now
appear to me to be false positives.

gcc/analyzer/ChangeLog:
	PR analyzer/98969
	* constraint-manager.cc (dead_svalue_purger::should_purge_p):
	Update for change to svalue::live_p.
	* program-state.cc (sm_state_map::on_liveness_change): Likewise.
	(program_state::detect_leaks): Likewise.
	* region-model-reachability.cc (reachable_regions::init_cluster):
	When dealing with a symbolic region, if the underlying pointer is
	implicitly live, add the region to the reachable regions.
	* region-model.cc (region_model::compare_initial_and_pointer):
	Move logic for detecting initial values of params to
	initial_svalue::initial_value_of_param_p.
	* svalue.cc (svalue::live_p): Convert "live_svalues" from a
	reference to a pointer; support it being NULL.
	(svalue::implicitly_live_p): Convert first param from a
	refererence to a pointer.
	(region_svalue::implicitly_live_p): Likewise.
	(constant_svalue::implicitly_live_p): Likewise.
	(initial_svalue::implicitly_live_p): Likewise.  Treat the initial
	values of params for the top level frame as still live.
	(initial_svalue::initial_value_of_param_p): New function, taken
	from a test in region_model::compare_initial_and_pointer.
	(unaryop_svalue::implicitly_live_p): Convert first param from a
	refererence to a pointer.
	(binop_svalue::implicitly_live_p): Likewise.
	(sub_svalue::implicitly_live_p): Likewise.
	(unmergeable_svalue::implicitly_live_p): Likewise.
	* svalue.h (svalue::live_p): Likewise.
	(svalue::implicitly_live_p): Likewise.
	(region_svalue::implicitly_live_p): Likewise.
	(constant_svalue::implicitly_live_p): Likewise.
	(initial_svalue::implicitly_live_p): Likewise.
	(initial_svalue::initial_value_of_param_p): New decl.
	(unaryop_svalue::implicitly_live_p): Convert first param from a
	refererence to a pointer.
	(binop_svalue::implicitly_live_p): Likewise.
	(sub_svalue::implicitly_live_p): Likewise.
	(unmergeable_svalue::implicitly_live_p): Likewise.

gcc/testsuite/ChangeLog:
	PR analyzer/98969
	* g++.dg/analyzer/pr99064.C: Convert dg-bogus to dg-warning.
	* gcc.dg/analyzer/pr96841.c: Add -Wno-analyzer-too-complex to
	options.  Remove false leak directive.
	* gcc.dg/analyzer/pr98969.c (test_1): Remove xfail from leak
	false positive.
	(test_3): New.

1 files changed, 2 insertions, 0 deletions

diff --git a/gcc/analyzer/region-model-reachability.cc b/gcc/analyzer/region-model-reachability.cc
index a988ffc..087185b 100644
--- a/gcc/analyzer/region-model-reachability.cc
+++ b/gcc/analyzer/region-model-reachability.cc
@@ -91,6 +91,8 @@ reachable_regions::init_cluster (const region *base_reg)
   if (const symbolic_region *sym_reg = base_reg->dyn_cast_symbolic_region ())
     {
       const svalue *ptr = sym_reg->get_pointer ();
+      if (ptr->implicitly_live_p (NULL, m_model))
+	add (base_reg, true);
       switch (ptr->get_kind ())
 	{
 	default: