x86: Update message for target_clones and unsupported ISAs

[gcc.git] / gcc / dse.c

diff --git a/gcc/dse.c b/gcc/dse.c
index 389c52d42842b30979b107ca22016454b390cc83..6f6f768f37112df2b2aee18ce722bcc8865dd43c 100644 (file)
--- a/gcc/dse.c
+++ b/gcc/dse.c
@@ -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);