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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug lto/99447] [11 Regression] ICE (segfault) in
 lookup_page_table_entry
Date: Wed, 17 Mar 2021 12:18:05 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99447

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hubicka at gcc dot gnu.org

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
More specifically, likely caused by g:ae99b315ba5b9e1ccc221b3c45de323cbc574=
400
which did

diff --git a/gcc/cfg.c b/gcc/cfg.c
index 529b6ed2105..e8bd1456c9f 100644
--- a/gcc/cfg.c
+++ b/gcc/cfg.c
@@ -102,8 +102,7 @@ free_block (basic_block bb)
    bb->succs =3D NULL;
    vec_free (bb->preds);
    bb->preds =3D NULL;
-   /* Do not free BB itself yet since we leak pointers to dead statements
-      that points to dead basic blocks.  */
+   ggc_free (bb);
 }

 /* Free the memory associated with the CFG in FN.  */

and the backtrace of the crash points at some RTX tree (if gtype-desc from
trunk still matches, it's likely SYMBOL_REF_DECL) refers to a GIMPLE stmt
via the callgraph edge ->call_stmt which refers to the CFG BB it is contain=
ed
in.

unfortunately it's not visible what pass/phase this segfault occurs in
(might be WPA function materialization or ltrans compilation).

That said, the ggc_free above looks like a bad idea until we can sort out
these issue.  So - should we simply revert the change again?=