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

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

[ktkachov at gcc dot gnu.org]

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

            Bug ID: 67030
           Summary: [6 Regression] ARM bootstrap failure due to
                    [-Werror=tautological-compare]
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Keywords: build
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ktkachov at gcc dot gnu.org
                CC: mpolacek at gcc dot gnu.org
  Target Milestone: ---
            Target: arm

I'm getting a bootstrap failure in stage 2 on arm-none-linux-gnueabihf due to
the new warning:
$SRC/gcc/cfgexpand.c: In function 'long long int expand_one_var(tree, bool,
bool)':
$SRC/gcc/defaults.h:1156:55: error: self-comparison always evaluates to false
[-Werror=tautological-compare]
 #define SUPPORTS_STACK_ALIGNMENT (MAX_STACK_ALIGNMENT > STACK_BOUNDARY)

Seems we need to be a bit smarter when it comes to macro expansions?

[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 #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Could you please try whether this patch helps?

diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 6a79b95..9fe9c5e 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -1890,6 +1890,10 @@ 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 (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))

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

[ktkachov at gcc dot gnu.org]

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

--- Comment #2 from ktkachov at gcc dot gnu.org ---
(In reply to Marek Polacek from comment #1)
> Could you please try whether this patch helps?
> 

Trying it out now...

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

[ktkachov at gcc dot gnu.org]

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

--- Comment #3 from ktkachov at gcc dot gnu.org ---
(In reply to ktkachov from comment #2)
> (In reply to Marek Polacek from comment #1)
> > Could you please try whether this patch helps?
> > 
> 
> Trying it out now...

Unfortunately still getting the error.
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.

[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 #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Testcase:

#define A a
#define B A
#define FOO (A > B)
int
main ()
{
  int a = 4;
  if (FOO)
    return 5;
}

[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))

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

[ktkachov at gcc dot gnu.org]

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

--- Comment #6 from ktkachov at gcc dot gnu.org ---
(In reply to Marek Polacek from comment #4)
> (In reply to ktkachov from comment #3)

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

Yes, that seems to work. Bootstrap proceeds from that point i.e. cfgexpand.c
compiles.

I have to go offline for the day, so I'll have the full bootstrap result
tomorrow but from what I can see this is an obvious fix (to my limited C
frontend experience) and it would be nice to have it in ASAP to fix arm
bootstrap.

Thanks for the quick response.

> 
> --- 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))

[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

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2015-07-27
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org
   Target Milestone|---                         |6.0
     Ever confirmed|0                           |1

--- Comment #7 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
(In reply to ktkachov from comment #6)
> Yes, that seems to work. Bootstrap proceeds from that point i.e. cfgexpand.c
> compiles.
> 
> I have to go offline for the day, so I'll have the full bootstrap result
> tomorrow but from what I can see this is an obvious fix (to my limited C
> frontend experience) and it would be nice to have it in ASAP to fix arm
> bootstrap.

Thanks, glad to hear that.  I'll commit the patch after doing some testing on
x86_64 (give me ~2 hours).

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

[vries at gcc dot gnu.org]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67030

vries at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vries at gcc dot gnu.org

--- Comment #8 from vries at gcc dot gnu.org ---
FYI, I'm running into this bootstrap failure on x86_64 (r226251):
...
src/gcc/ipa-devirt.c: In function ‘bool types_same_for_odr(const_tree,
const_tree, bool)’:
src/gcc/ipa-devirt.c:553:8: error: self-comparison always evaluates to false
[-Werror=tautological-compare]
        != (TYPE_BINFO (type1) == NULL_TREE))
...
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Subject: [Bug bootstrap/67030] [6 Regression] ARM bootstrap failure due to [-Werror=tautological-compare]
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67030

--- Comment #9 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
(In reply to vries from comment #8)
> FYI, I'm running into this bootstrap failure on x86_64 (r226251):

Weird I don't see this myself.

> ...
> src/gcc/ipa-devirt.c: In function ‘bool types_same_for_odr(const_tree,
> const_tree, bool)’:
> src/gcc/ipa-devirt.c:553:8: error: self-comparison always evaluates to false
> [-Werror=tautological-compare]
>         != (TYPE_BINFO (type1) == NULL_TREE))
> ...

 551       if (TREE_CODE (type1) == RECORD_TYPE
 552           && (TYPE_BINFO (type1) == NULL_TREE)
 553               != (TYPE_BINFO (type1) == NULL_TREE))

Ok, that's a clear typo; something that this warning is designed to detect. 
I'm fixing this separately.  Thanks for reporting.
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Subject: [Bug c/67029] gcc-5.2.0 unable to find a register to spill with O3 fsched-pressure fschedule-insns
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idg029

--- Comment #4 from ziebell_marco at posteo dot de ---
Created attachment 36070
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id6070&actioníit
preprocessed version of addressmap.c

[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 #10 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Mon Jul 27 19:09:27 2015
New Revision: 226264

URL: https://gcc.gnu.org/viewcvs?rev=226264&root=gcc&view=rev
Log:
        PR bootstrap/67030
        * c-common.c (warn_tautological_cmp): Don't warn for macro expansion.

        * c-c++-common/Wtautological-compare-2.c: New test.

Added:
    trunk/gcc/testsuite/c-c++-common/Wtautological-compare-2.c
Modified:
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c-common.c
    trunk/gcc/testsuite/ChangeLog

[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

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #11 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed (fingers crossed).

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

[christian.joensson at gmail dot com]

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

--- Comment #12 from Christian Joensson <christian.joensson at gmail dot com> ---
Still...
../../gcc/ipa-devirt.c: In function ‘bool types_same_for_odr(const_tree,
const_tree, bool ’:
../../gcc/ipa-devirt.c:553:8: error: self-comparison always evaluates to false
[-Werror=tautological-compare]
        != (TYPE_BINFO (type1) == NULL_TREE))
        ^
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Subject: [Bug rtl-optimization/67028] combine bug. Different assumptions about subreg in different places.
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idg028

Segher Boessenkool <segher at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|renlin at gcc dot gnu.org          |segher at gcc dot gnu.org

--- Comment #4 from Segher Boessenkool <segher at gcc dot gnu.org> ---
I'm testing a patch.

[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 #13 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
That is fixed as well now.

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

[christian.joensson at gmail dot com]

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

--- Comment #14 from Christian Joensson <christian.joensson at gmail dot com> ---
(In reply to Marek Polacek from comment #13)
> That is fixed as well now.

Yep. Thanks.

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

[ktkachov at gcc dot gnu.org]

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

--- Comment #15 from ktkachov at gcc dot gnu.org ---
Yeah, that problem is fixed.
Now bootstrap fails due to:
gcc/vec.h:307:3: error: attempt to free a non-heap object 'intersecting'
[-Werror=free-nonheap-object]
   ::free (v);
   ^


But that must be a different problem.
Will analyze and file a separate PR...

[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 #16 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Yeah, that doesn't look related to this warning at all.  Thanks for checking.

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

[ktkachov at gcc dot gnu.org]

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

--- Comment #17 from ktkachov at gcc dot gnu.org ---
(In reply to Marek Polacek from comment #16)
> Yeah, that doesn't look related to this warning at all.  Thanks for checking.

Yeah, turns out that was due to a private patch of mine.
Clean trunk bootstraps ok.
Sorry for the noise.