On 11-08-22 07:10 , Dodji Seketeli wrote:
Hello,In c_common_read_pch when gt_pch_restore loads a new pch, the previous line table (referenced from the global 'line_table') is garbage-collected and a new one is built. As the global instance of cpp_reader referenced by the local variable 'pfile' has a pfile->line_table member that references the 'line_table' global, pfile->line_table needs to be set to the new value of line_table after gt_pch_restore is called, otherwise pfile->line_table points to garbage-collected memory. This is what the call to cpp_set_line_map in c_common_read_pch is for. The problem is that cpp_set_line_map is called too late as cpp_read_state (called before cpp_set_line_map) indirectly touches some pfile->line_table dangling garbage-collected memory[1]. This doesn't cause any visible havoc in trunk yet but I am seeing it crashing as I am fiddling with line map stuff on the side. The two-liner patch below just calls cpp_set_line_map right after gt_pch_restore to restore pfile->line_table before anyone touches it. [1]: This happens via cpp_read_state -> _cpp_create_definition -> _cpp_create_iso_definition -> _cpp_lex_token -> _cpp_lex_direct -> linemap_position_for_column. Bootstrapped and tested on x86_64-unknown-linux-gnu against trunk. OK for trunk? gcc/ * c-family/c-pch.c (c_common_read_pch): Re-set line table right after reading in the pch.
OK. Diego.
