[Bug tree-optimization/21399] [4.1 Regression] libstdc++ 12077.cc ICE

[steven at gcc dot gnu dot org]

------- Additional Comments From steven at gcc dot gnu dot org  2005-05-16 00:26 -------
We have this code in tree-ssa-propagate.c:1052-1065: 
 
          if (did_replace) 
            { 
              fold_stmt (bsi_stmt_ptr (i)); 
              stmt = bsi_stmt(i); 
 
              /* If we folded a builtin function, we'll likely 
                 need to rename VDEFs.  */ 
              mark_new_vars_to_rename (stmt); 
 
              /* If we cleaned up EH information from the statement, 
                 remove EH edges.  */ 
              if (maybe_clean_eh_stmt (stmt)) 
                tree_purge_dead_eh_edges (bb); 
            } 
 
But maybe_clean_eh_stmt returns false.  Why?? 
 
Because we replace the entire statement apparently.  So we get to tree-eh.c: 
 
 
Breakpoint 4, substitute_and_fold (prop_value=0xf3e3a0) at 
tree-ssa-propagate.c:1054 
1054                  fold_stmt (bsi_stmt_ptr (i)); 
(gdb) p *bsi_stmt_ptr(i) 
$12 = 0x2a95896550 
(gdb) p debug_generic_stmt (*bsi_stmt_ptr(i)) 
#   TMT.1D.2025_4 = V_MAY_DEF <TMT.1D.2025_3>; 
fputs (&"a"[0], fileD.2015_2); 
$13 = void 
(gdb) cont 
Continuing. 
 
Breakpoint 3, substitute_and_fold (prop_value=0xf3e3a0) at 
tree-ssa-propagate.c:1063 
1063                  if (maybe_clean_eh_stmt (stmt)) 
(gdb) p stmt 
$14 = 0x2a95896d70 
1063                  if (maybe_clean_eh_stmt (stmt)) 
(gdb) p debug_generic_stmt(stmt) 
#   TMT.1D.2025_4 = V_MAY_DEF <TMT.1D.2025_3>; 
__builtin_fputc (97, fileD.2015_2); 
$8 = void 
(gdb) step 
maybe_clean_eh_stmt (stmt=0x2a95896d70) at tree-eh.c:2040 
2040      if (!tree_could_throw_p (stmt)) 
(gdb) next 
2041        if (remove_stmt_from_eh_region (stmt)) 
(gdb) 
2043      return false; 
(gdb)     
 
So we try to remove the _new_ statement from the EH region, and leave the 
old one right there. 
 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21399