Hi!
The assume_query constructor does
assume_query::assume_query (function *f, bitmap p) : m_parm_list (p),
m_func (f)
where m_parm_list is bitmap &. This is compile time UB, because
as soon as the constructor returns, m_parm_list reference is still
bound to the parameter of the constructor which is no longer in scope.
Now, one possible fix would be change the ctor argument to be bitmap &,
but that doesn't really work because in the only user of that class
we have
auto_bitmap decls;
...
assume_query query (fun, decls);
and auto_bitmap just has
operator bitmap () { return &m_bits; }
Could be perhaps const bitmap &, but why? bitmap is a pointer:
typedef class bitmap_head *bitmap;
and the EXECUTE_IF_SET_IN_BITMAP macros don't really change that point,
they just inspect what is inside of that bitmap_head the pointer points
to.
So, the simplest I think is avoid references (which cause even worse
code as it has to be dereferenced twice rather than once).
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2025-01-23 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/118605
* tree-assume.cc (assume_query::m_parm_list): Change type
from bitmap & to bitmap.
--- gcc/tree-assume.cc.jj 2025-01-02 11:23:27.341365743 +0100
+++ gcc/tree-assume.cc 2025-01-22 13:06:09.364187391 +0100
@@ -97,7 +97,7 @@ protected:
ssa_lazy_cache m_path; // Values found on path
ssa_lazy_cache m_parms; // Cumulative parameter value calculated
- bitmap &m_parm_list; // Parameter ssa-names list.
+ bitmap m_parm_list; // Parameter ssa-names list.
function *m_func;
};
Jakub
