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Various false positives from -fanalyzer involve SSA names in loops,
where sm-state associated with an SSA name from one iteration is
erroneously reused in a subsequent iteration.
For example, PR analyzer/99716 describes a false
"double 'fclose' of FILE 'fp'"
on:
for (i = 0; i < 2; ++i) {
FILE *fp = fopen ("/tmp/test", "w");
fprintf (fp, "hello");
fclose (fp);
}
where the gimple of the loop body is:
fp_7 = fopen ("/tmp/test", "w");
__builtin_fwrite ("hello", 1, 5, fp_7);
fclose (fp_7);
i_10 = i_1 + 1;
where fp_7 transitions to "closed" at the fclose, but is not
reset at the subsequent fopen, leading to the false positive
when the fclose is re-reached.
The fix is to reset sm-state for svalues that involve an SSA name
at the SSA name's def-stmt, since the def-stmt effectively changes
the meaning of those related svalues.
gcc/analyzer/ChangeLog:
PR analyzer/93695
PR analyzer/99044
PR analyzer/99716
* engine.cc (exploded_node::on_stmt): Clear sm-state involving
an SSA name at the def-stmt of that SSA name.
* program-state.cc (sm_state_map::purge_state_involving): New.
* program-state.h (sm_state_map::purge_state_involving): New decl.
* region-model.cc (selftest::test_involves_p): New.
(selftest::analyzer_region_model_cc_tests): Call it.
* svalue.cc (class involvement_visitor): New class
(svalue::involves_p): New.
* svalue.h (svalue::involves_p): New decl.
gcc/testsuite/ChangeLog:
PR analyzer/93695
PR analyzer/99044
PR analyzer/99716
* gcc.dg/analyzer/attr-malloc-CVE-2019-19078-usb-leak.c: Remove
xfail.
* gcc.dg/analyzer/pr93695-1.c: New test.
* gcc.dg/analyzer/pr99044-1.c: New test.
* gcc.dg/analyzer/pr99044-2.c: New test.
* gcc.dg/analyzer/pr99716-1.c: New test.
* gcc.dg/analyzer/pr99716-2.c: New test.
* gcc.dg/analyzer/pr99716-3.c: New test.
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