[gcc r12-5630] ipa-param-manip: Be careful about a reallocating hash_map

[Martin Jambor <jamborm@gcc.gnu.org>]

https://gcc.gnu.org/g:b3f60112edcb85b459e60f66c44a55138b1cef49

commit r12-5630-gb3f60112edcb85b459e60f66c44a55138b1cef49
Author: Martin Jambor <mjambor@suse.cz>
Date:   Tue Nov 30 15:35:18 2021 +0100

    ipa-param-manip: Be careful about a reallocating hash_map
    
    PR 103449 revealed that when I was storing result of one hash_map
    lookup into another entry in the hash_map, I was still accessing the
    entry in the table, which meanwhile could get reallocated, making the
    accesses invalid-after-free.
    
    Fixed with the following, which also simplifies the return statement
    which must have been true even now.
    
    gcc/ChangeLog:
    
    2021-11-29  Martin Liska  <mliska@suse.cz>
                Martin Jambor  <mjambor@suse.cz>
    
            PR ipa/103449
            * ipa-param-manipulation.c
            (ipa_param_body_adjustments::prepare_debug_expressions): Be
            careful about hash_map reallocating itself.  Simpify a return
            which always returns true.

Diff:
---
 gcc/ipa-param-manipulation.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/gcc/ipa-param-manipulation.c b/gcc/ipa-param-manipulation.c
index 479c20b3871..163af94cde0 100644
--- a/gcc/ipa-param-manipulation.c
+++ b/gcc/ipa-param-manipulation.c
@@ -1279,9 +1279,10 @@ ipa_param_body_adjustments::prepare_debug_expressions (tree dead_ssa)
       if (gimple_assign_copy_p (def)
 	  && TREE_CODE (gimple_assign_rhs1 (def)) == SSA_NAME)
 	{
-	  tree *d = m_dead_ssa_debug_equiv.get (gimple_assign_rhs1 (def));
-	  m_dead_ssa_debug_equiv.put (dead_ssa, *d);
-	  return (*d != NULL_TREE);
+	  tree d = *m_dead_ssa_debug_equiv.get (gimple_assign_rhs1 (def));
+	  gcc_assert (d);
+	  m_dead_ssa_debug_equiv.put (dead_ssa, d);
+	  return true;
 	}
 
       tree val