[Bug ada/98773] New: [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[Bug ada/98773] New: [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[ro at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

            Bug ID: 98773
           Summary: [11 regression] Bootstrap failure: "Trmsgggg"
                    conflicts with declaration
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ada
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ro at gcc dot gnu.org
  Target Milestone: ---
            Target: i386-pc-solaris2.11, sparc-sun-solaris2.11

Between 20210119 (8227106f5668c8fb1f0c5d2026e44cc0b84ee991) and 20210120
(261cdd23195bc921737fd7a44e34a93aaaaccc44),
bootstrap began to fail in stage 2:

* Solaris/x86:

a-except.adb:625:04: "Trmsgggg" conflicts with declaration at line 624

* Solaris/SPARC:

osint.ads:51:04: "Taaaaaaaaaaaaaaaa" conflicts with declaration at line 50
a-except.adb:625:04: "Trrrrrrr" conflicts with declaration at line 624
butil.adb:401:55: "T" conflicts with declaration at line 397
osint.ads:51:04: "Taaaaaaaaaaaaaaaa" conflicts with declaration at line 50
erroutc.adb:383:55: "T" conflicts with declaration at line 381
errout.adb:787:07: "Tcccc" conflicts with declaration at line 786
exp_ch6.adb:82:04: "Tbbbbbbbbbbbbbbbb" conflicts with declaration at
exp_ch6.ads:59
sem_util.adb:885:30: "T" conflicts with declaration at line 881
sem_util.adb:885:30: "T" conflicts with declaration at line 881

Seems like a miscompilation; haven't started a reghunt yet.

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[ro at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

Rainer Orth <ro at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.0

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[ro at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

Rainer Orth <ro at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|i386-pc-solaris2.11,        |i386-pc-solaris2.11,
                   |sparc-sun-solaris2.11       |sparc-sun-solaris2.11,
                   |                            |i686-pc-linux-gnu

--- Comment #1 from Rainer Orth <ro at gcc dot gnu.org> ---
FWIW it seems to be a 32-bit-only issue: while both amd64-pc-solaris2.11 and
x86_64-pc-linux-gnu bootstraps worked fine, i686-pc-linux-gnu is similarly
broken:

targparm.adb:76:04: "Tbbccstr" conflicts with declaration at line 75

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[ro at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

Rainer Orth <ro at gcc dot gnu.org> changed:

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

--- Comment #2 from Rainer Orth <ro at gcc dot gnu.org> ---
I misspoke initially: the failure happens in stage 3.

I've now run a reghunt and found this patch as the culprit:

commit 261cdd23195bc921737fd7a44e34a93aaaaccc44
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Jan 20 11:28:30 2021 +0100

    Handle overflow in dependence analysis lambda ops gracefully

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Hmm, can you see whether just the

diff --git a/gcc/tree-data-ref.c b/gcc/tree-data-ref.c
index 9d07b415e9d..d19c5eb51e4 100644
--- a/gcc/tree-data-ref.c
+++ b/gcc/tree-data-ref.c
@@ -3924,9 +3924,25 @@ initialize_matrix_A (lambda_matrix A, tree chrec,
unsigned index, int mult)
   switch (TREE_CODE (chrec))
     {
     case POLYNOMIAL_CHREC:
-      if (!cst_and_fits_in_hwi (CHREC_RIGHT (chrec)))
+      /* CHREC_RIGHT and its negated value should fit in a lambda_int.
+        Pointer typed chrecs right are to be interpreted signed.  */
+      HOST_WIDE_INT chrec_right;
+      if (POINTER_TYPE_P (chrec_type (chrec)))
+       {
+         if (!cst_and_fits_in_hwi (CHREC_RIGHT (chrec)))
+           return chrec_dont_know;
+         chrec_right = int_cst_value (CHREC_RIGHT (chrec));
+       }
+      else
+       {
+         if (!tree_fits_shwi_p (CHREC_RIGHT (chrec)))
+           return chrec_dont_know;
+         chrec_right = tree_to_shwi (CHREC_RIGHT (chrec));
+       }
+      /* We want to be able to negate without overflow.  */
+      if (chrec_right == HOST_WIDE_INT_MIN)
        return chrec_dont_know;
-      A[index][0] = mult * int_cst_value (CHREC_RIGHT (chrec));
+      A[index][0] = mult * chrec_right;
       return initialize_matrix_A (A, CHREC_LEFT (chrec), index + 1, mult);

     case PLUS_EXPR:

part of the change is enough to trigger the failure?

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-01-22
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
So I wasn't able to reproduce on a x86_64 host bootstrapping a 32bit
compiler configured as

--enable-languages=c++,ada --disable-multilib --target=i686-pc-linux-gnu
--host=i686-pc-linux-gnu --build=i686-pc-linux-gnu --without-zstd

with a host 64bit GCC 7 (using -m32).

Since the rev. didn't fix a regression reverting is a good option but of course
it would be nice to understand why it's broken ... :/

Any hint as to why the above isn't enough to reproduce?

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[ro at CeBiTec dot Uni-Bielefeld.DE]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

--- Comment #5 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> ---
> --- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
> So I wasn't able to reproduce on a x86_64 host bootstrapping a 32bit
> compiler configured as
>
> --enable-languages=c++,ada --disable-multilib --target=i686-pc-linux-gnu
> --host=i686-pc-linux-gnu --build=i686-pc-linux-gnu --without-zstd
>
> with a host 64bit GCC 7 (using -m32).

That's almost the same I've been using.  My configure options boil down
to

configure \
  --target=i686-pc-linux-gnu --build=i686-pc-linux-gnu --host=i686-pc-linux-gnu
  --enable-targets=all \
  --with-as=/vol/gcc/bin/i686/gas-2.35 --with-gnu-as \
  --with-ld=/vol/gcc/bin/i686/gld-2.35 --with-gnu-ld \
  --enable-languages=all,ada,obj-c++,go \
  --with-zstd-include=/vol/gcc/include --with-zstd-lib=/vol/gcc/lib/i686 

Maybe the use of binutils 2.35 makes a difference?  Those are
locally-built vanilla versions, btw., nothing delivered by a distro.
However, I've seen the same failure with native Solaris assembler and
linker, making it unlikely that the binutils version is a factor.

> Since the rev. didn't fix a regression reverting is a good option but of course
> it would be nice to understand why it's broken ... :/

Absolutely, otherwise this is going to raise its ugly head again.

> Any hint as to why the above isn't enough to reproduce?

Nothing obvious.

However, a sparc-sun-solaris2.11 bootstrap with just the tree-data-ref.c
snippet just finished, failing just as with your full patch.

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
Ok, so it's eventually a multilib building (--enable-targets=all) though the
errors sound like frontend errors ...

But if just the tree-data-ref.c hunk is enough to trigger it then it
hints at an issue with

+         if (!tree_fits_shwi_p (CHREC_RIGHT (chrec)))
+           return chrec_dont_know;
+         chrec_right = tree_to_shwi (CHREC_RIGHT (chrec));

which will interpret -1U as -1U instead of -1 for unsigned CHRECs.  It will
treat { 0, +, 255 } (all unsigned char) plain instead of re-interpreting
it as { 0, +, -1 }, maybe that was a wrong "fix".

I have a testcase, -O3 -m32 fails:

char a[128];

void __attribute__((noipa))
foo ()
{
  for (unsigned i = 27; i >= 5; --i)
    a[i] = a[i-5];
}

int main()
{
  __builtin_memcpy (a, "Hello World", sizeof ("Hello World"));
  foo ();
  if (__builtin_memcmp (a + 5, "Hello World", sizeof ("Hello World")) != 0)
    __builtin_abort ();
  return 0;
}

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 50027
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50027&action=edit
patch

Patch I am testing (note I couldn't reproduce the issue so it would be nice if
you can verify the fix).

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[ro at CeBiTec dot Uni-Bielefeld.DE]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

--- Comment #8 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> ---
> --- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---

> Patch I am testing (note I couldn't reproduce the issue so it would be nice if
> you can verify the fix).

Sure: I'll first try another i686-pc-linux-gnu bootstrap.  Solaris will
have to wait: the machines are currently busy running the weekly
bootstraps; I'll try that later this weekend.  Thanks.

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>:

https://gcc.gnu.org/g:8bad25eb56bd16f3482f856a75b1c1ae5cfe1c4f

commit r11-6854-g8bad25eb56bd16f3482f856a75b1c1ae5cfe1c4f
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Jan 22 11:29:17 2021 +0100

    middle-end/98773 - always sign extend CHREC_RIGHT

    The previous change exposed a miscompile when trying to interpret
    CHREC_RIGHT correctly which in fact it already was to the extent
    it is used.  The following reverts this part of the change, only
    retaining the singling out of HOST_WIDE_INT_MIN.

    2021-01-22  Richard Biener  <rguenther@suse.de>

            PR middle-end/98773
            * tree-data-ref.c (initalize_matrix_A): Revert previous
            change, retaining failing on HOST_WIDE_INT_MIN CHREC_RIGHT.

            * gcc.dg/torture/pr98773.c: New testcase.

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[ro at CeBiTec dot Uni-Bielefeld.DE]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

--- Comment #10 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> ---
> --- Comment #8 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot
> Uni-Bielefeld.DE> ---
[...]
> Sure: I'll first try another i686-pc-linux-gnu bootstrap.  Solaris will

The i686-pc-linux-gnu bootstrap is now well beyond the point of the
previous failures, so things are certainly looking good.  Thanks.

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

Martin Liška <marxin at gcc dot gnu.org> changed:

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

--- Comment #11 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to ro@CeBiTec.Uni-Bielefeld.DE from comment #10)
> > --- Comment #8 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot
> > Uni-Bielefeld.DE> ---
> [...]
> > Sure: I'll first try another i686-pc-linux-gnu bootstrap.  Solaris will
> 
> The i686-pc-linux-gnu bootstrap is now well beyond the point of the
> previous failures, so things are certainly looking good.  Thanks.

Yes, I can confirm that Ada bootstrap works for me now on i686-linux-gnu
machine.

[Bug ada/98773] [11 regression] Bootstrap failure: "Trmsgggg" conflicts with declaration

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98773

Richard Biener <rguenth at gcc dot gnu.org> changed:

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

--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed then.