Re: [PATCH] Fix condition in ira-color.c and lra-spills.c (PR c/61271)

[Marek Polacek <polacek at redhat dot com>]

On Thu, Aug 21, 2014 at 03:38:25PM -0400, Vladimir Makarov wrote:
> Sorry, Marek.  I guess it is wrong.  STACK_GROWS_DOWNWARD is only 0 or 1
> in these files (it is achieved by redefinition of STACK_GROWS_DOWNWARD
> in the files).  FAME_GROWS_DOWNWARD can be 0 or anything non-zero (even
> non-constant) as tm.texi contains
> 
> @defmac FRAME_GROWS_DOWNWARD
> Define this macro to nonzero value if the addresses of local variable slots
> are at negative offsets from the frame pointer.
> @end defmac
> 
> It works now as all machine description files use 1 as non-zero value.
> 
> So the documentation should be changed but it is not wise, error prune,
> and right now the macro value can be non-constant during compilation
> time theoretically.
 
Whoops, that is sneaky, thanks for the exaplanation.

> So you need another way to transform the expressions to get rid of the
> warning.
> 
> As I remember the code was actually taken from the old RA and not simple
> as it looks.
 
So what we can do is to just wrap the LHS of the comparison in parens;
this ought to suppress the warning.

Bootstrapped/regtested on x86_64-linux, ok for trunk?

2014-08-22  Marek Polacek  <polacek@redhat.com>

	PR c/61271
	* ira-color.c (coalesced_pseudo_reg_slot_compare): Wrap LHS of
	a comparison in parens.
	* lra-spills.c (pseudo_reg_slot_compare): Wrap LHS of a comparison
	in parens.

diff --git gcc/ira-color.c gcc/ira-color.c
index 36c3c87..e2ea359 100644
--- gcc/ira-color.c
+++ gcc/ira-color.c
@@ -3850,7 +3850,7 @@ coalesced_pseudo_reg_slot_compare (const void *v1p, const void *v2p)
   slot_num2 = -ALLOCNO_HARD_REGNO (a2);
   if ((diff = slot_num1 - slot_num2) != 0)
     return (frame_pointer_needed
-	    || !FRAME_GROWS_DOWNWARD == STACK_GROWS_DOWNWARD ? diff : -diff);
+	    || (!FRAME_GROWS_DOWNWARD) == STACK_GROWS_DOWNWARD ? diff : -diff);
   total_size1 = MAX (PSEUDO_REGNO_BYTES (regno1),
 		     regno_max_ref_width[regno1]);
   total_size2 = MAX (PSEUDO_REGNO_BYTES (regno2),
diff --git gcc/lra-spills.c gcc/lra-spills.c
index 50f63fc..38a81e6 100644
--- gcc/lra-spills.c
+++ gcc/lra-spills.c
@@ -237,7 +237,7 @@ pseudo_reg_slot_compare (const void *v1p, const void *v2p)
   slot_num2 = pseudo_slots[regno2].slot_num;
   if ((diff = slot_num1 - slot_num2) != 0)
     return (frame_pointer_needed
-	    || !FRAME_GROWS_DOWNWARD == STACK_GROWS_DOWNWARD ? diff : -diff);
+	    || (!FRAME_GROWS_DOWNWARD) == STACK_GROWS_DOWNWARD ? diff : -diff);
   total_size1 = GET_MODE_SIZE (lra_reg_info[regno1].biggest_mode);
   total_size2 = GET_MODE_SIZE (lra_reg_info[regno2].biggest_mode);
   if ((diff = total_size2 - total_size1) != 0)


	Marek