[Bug bootstrap/67030] [6 Regression] ARM bootstrap failure due to [-Werror=tautological-compare]

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67030

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
(In reply to ktkachov from comment #3)
> Unfortunately still getting the error.

Sorry about that.

> One thing I missed out from the original error message is this note:
> 
> error: self-comparison always evaluates to false
> [-Werror=tautological-compare]
>  #define SUPPORTS_STACK_ALIGNMENT (MAX_STACK_ALIGNMENT > STACK_BOUNDARY)
> 
> $SRC/gcc/cfgexpand.c:1268:7: note: in expansion of macro
> 'SUPPORTS_STACK_ALIGNMENT'
>    if (SUPPORTS_STACK_ALIGNMENT
>        ^
> 
> Don't know if that helps.

Actually, that helps.  I bet the following works.  Mind giving this one a spin?

--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -1890,6 +1890,11 @@ warn_tautological_cmp (location_t loc, enum tree_code
code, tree lhs, tree rhs)
   if (TREE_CODE_CLASS (code) != tcc_comparison)
     return;

+  if (from_macro_expansion_at (loc)
+      || from_macro_expansion_at (EXPR_LOCATION (lhs))
+      || from_macro_expansion_at (EXPR_LOCATION (rhs)))
+    return;
+
   /* We do not warn for constants because they are typical of macro
      expansions that test for features, sizeof, and similar.  */
   if (CONSTANT_CLASS_P (lhs) || CONSTANT_CLASS_P (rhs))