diff options
Diffstat (limited to 'gcc/dse.c')
| -rw-r--r-- | gcc/dse.c | 23 |
1 files changed, 22 insertions, 1 deletions
@@ -2072,8 +2072,29 @@ check_mem_read_rtx (rtx *loc, bb_info_t bb_info) insn_info = bb_info->last_insn; if ((MEM_ALIAS_SET (mem) == ALIAS_SET_MEMORY_BARRIER) - || (MEM_VOLATILE_P (mem))) + || MEM_VOLATILE_P (mem)) { + if (crtl->stack_protect_guard + && (MEM_EXPR (mem) == crtl->stack_protect_guard + || (crtl->stack_protect_guard_decl + && MEM_EXPR (mem) == crtl->stack_protect_guard_decl)) + && MEM_VOLATILE_P (mem)) + { + /* This is either the stack protector canary on the stack, + which ought to be written by a MEM_VOLATILE_P store and + thus shouldn't be deleted and is read at the very end of + function, but shouldn't conflict with any other store. + Or it is __stack_chk_guard variable or TLS or whatever else + MEM holding the canary value, which really shouldn't be + ever modified in -fstack-protector* protected functions, + otherwise the prologue store wouldn't match the epilogue + check. */ + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, " stack protector canary read ignored.\n"); + insn_info->cannot_delete = true; + return; + } + if (dump_file && (dump_flags & TDF_DETAILS)) fprintf (dump_file, " adding wild read, volatile or barrier.\n"); add_wild_read (bb_info); |