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| author | David Malcolm <dmalcolm@redhat.com> | 2020-09-16 13:12:39 -0400 |
|---|---|---|
| committer | David Malcolm <dmalcolm@redhat.com> | 2020-09-16 18:56:50 -0400 |
| commit | e097c9ab83192fc2f738ec6426a275282e9a51ea (patch) | |
| tree | f50440aa428bda9f922ee6871aec460eb9043031 | |
| parent | 3f4b15f52f4d5f202a7f27bdbb41a8fff218d323 (diff) | |
| download | gcc-e097c9ab83192fc2f738ec6426a275282e9a51ea.zip gcc-e097c9ab83192fc2f738ec6426a275282e9a51ea.tar.gz gcc-e097c9ab83192fc2f738ec6426a275282e9a51ea.tar.bz2 | |
analyzer: getchar has no side-effects
Seen whilst debugging another issue, where the analyzer was assuming
conservatively that a call to getchar could clobber a global.
This is handled for most of the other stdio functions by the list
in sm-file.cc
gcc/analyzer/ChangeLog:
* region-model.cc (region_model::on_call_pre): Treat getchar as
having no side-effects.
gcc/testsuite/ChangeLog:
* gcc.dg/analyzer/getchar-1.c: New test.
| -rw-r--r-- | gcc/analyzer/region-model.cc | 5 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/analyzer/getchar-1.c | 19 |
2 files changed, 24 insertions, 0 deletions
diff --git a/gcc/analyzer/region-model.cc b/gcc/analyzer/region-model.cc index d53272e..1312391 100644 --- a/gcc/analyzer/region-model.cc +++ b/gcc/analyzer/region-model.cc @@ -732,6 +732,11 @@ region_model::on_call_pre (const gcall *call, region_model_context *ctxt) return impl_call_calloc (cd); else if (is_named_call_p (callee_fndecl, "alloca", call, 1)) return impl_call_alloca (cd); + else if (is_named_call_p (callee_fndecl, "getchar", call, 0)) + { + /* No side-effects (tracking stream state is out-of-scope + for the analyzer). */ + } else if (is_named_call_p (callee_fndecl, "memset", call, 3)) { impl_call_memset (cd); diff --git a/gcc/testsuite/gcc.dg/analyzer/getchar-1.c b/gcc/testsuite/gcc.dg/analyzer/getchar-1.c new file mode 100644 index 0000000..25595e0 --- /dev/null +++ b/gcc/testsuite/gcc.dg/analyzer/getchar-1.c @@ -0,0 +1,19 @@ +#include <stdio.h> +#include "analyzer-decls.h" + +int test_1 (void) +{ + int c = getchar (); + return c; +} + +int glob_2; +int test_2 (void) +{ + int c; + glob_2 = 42; + __analyzer_eval (glob_2 == 42); /* { dg-warning "TRUE" } */ + c = getchar (); + __analyzer_eval (glob_2 == 42); /* { dg-warning "TRUE" } */ + return c; +} |