[Bug c/109778] New: Wrong code at -O3 on x86_64-linux-gnu since GCC-12.2

[Bug c/109778] New: Wrong code at -O3 on x86_64-linux-gnu since GCC-12.2

[shaohua.li at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

            Bug ID: 109778
           Summary: Wrong code at -O3 on x86_64-linux-gnu since GCC-12.2
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shaohua.li at inf dot ethz.ch
  Target Milestone: ---

gcc trunk at -O3 emits wrong code. This seems to be a bug since gcc-12.2

Compiler explorer: https://godbolt.org/z/E5aqnMK6Y


$ cat a.c
int printf(const char *, ...);
int a, b, c, d;
int *e = &c;
unsigned f(unsigned char g) {
  g = 1 | g << 1;
  g = g >> 4 | g << 4;
  return g;
}
void h(unsigned g) { *e = 8 > f(g + 86) - 86; }
int main() {
  d = a && b;
  h(d + 4);
  printf("%d\n", c);
}
$
$ gcc-tk -O0 a.c && ./a.out
1
$ gcc-tk -O3 a.c && ./a.out
0
$
$ gcc-tk -v
Using built-in specs.
COLLECT_GCC=gcc-tk
COLLECT_LTO_WRAPPER=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-b7fe38c14e5f1bc32950c7b2ffc8537c7c381af4/libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure --disable-multilib --disable-bootstrap
--enable-languages=c,c++
--prefix=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-b7fe38c14e5f1bc32950c7b2ffc8537c7c381af4
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 20230506 (experimental) (GCC)
$

[Bug tree-optimization/109778] [12/13/14 Regression] Wrong code at -O1 and above on x86_64-linux-gnu since GCC-12.2

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2023-05-08
     Ever confirmed|0                           |1
           Keywords|                            |wrong-code
          Component|c                           |tree-optimization
             Status|UNCONFIRMED                 |NEW
            Summary|Wrong code at -O3 on        |[12/13/14 Regression] Wrong
                   |x86_64-linux-gnu since      |code at -O1 and above on
                   |GCC-12.2                    |x86_64-linux-gnu since
                   |                            |GCC-12.2

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
ccp2:
Visiting statement:
_16 = (unsigned intD.9) g_15;
which is likely CONSTANT
Lattice value changed to CONSTANT 0xdb (0x20).  Adding SSA edges to worklist.
marking stmt to be not simulated again

Visiting statement:
_17 = _16 + 4294967210;
which is likely CONSTANT
Lattice value changed to CONSTANT 0x85 (0x20).  Adding SSA edges to worklist.
marking stmt to be not simulated again

Visiting statement:
_18 = _17 <= 7;
which is likely CONSTANT
Lattice value changed to CONSTANT 0.  Adding SSA edges to worklist.
marking stmt to be not simulated again


Note this is with -O1 with:
```

int printf(const char *, ...);
int a, b, c, d;
int *e = &c;
static inline unsigned f(unsigned char g) {
  g = 1 | g << 1;
  g = g >> 4 | g << 4;
  return g;
}
static inline void h(unsigned g) { *e = 8 > f(g + 86) - 86; }
int main() {
  d = a && b;
  h(d + 4);
  printf("%d\n", c);
}
```

[Bug tree-optimization/109778] [13/14 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |12.2.0
      Known to fail|                            |13.1.0
            Summary|[12/13/14 Regression] Wrong |[13/14 Regression] Wrong
                   |code at -O1 and above on    |code at -O1 and above on
                   |x86_64-linux-gnu since      |x86_64-linux-gnu
                   |GCC-12.2                    |
   Target Milestone|---                         |13.2

[Bug tree-optimization/109778] [13/14 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

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

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Bisected to r13-1100-gacb1e6f43dc2bbedd1248ea61c

[Bug tree-optimization/109778] [13/14 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |aldyh at gcc dot gnu.org,
                   |                            |amacleod at redhat dot com

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Looking at the #c1 -O3 differences, before that the ranger is able to handle
all ranges nicely, as f is being called with [90, 91], which results in [181,
183] before the rotate (which previously wasn't used, but 2 shifts + or), and
because the values in that range are 0xb5, 0xb6 and 0xb7 and that rotated by 4
is 0x5b, 0x6b, 0x7b we made [0x5b, 0x7b] range out of that (i.e. [91, 123]) and
that minus 86 is [5, 37].
Now, with the above mentioned commit, we instead have r>>= 4 in the code,
apparently
that is something range-op.cc doesn't handle (but could, worst case with
pretending it is 2 shifts plus or).  So that is one thing that should be done.

The other is a bug in the wi::[lr]rotate implementation, tree-ssa-ccp.cc is the
only caller of those which passes non-zero width and that is what isn't handled
correctly.

--- gcc/wide-int.h.jj   2023-04-18 11:00:39.926725744 +0200
+++ gcc/wide-int.h      2023-05-08 23:36:41.104412818 +0200
@@ -3187,9 +3187,11 @@ wi::lrotate (const T1 &x, const T2 &y, u
     width = precision;
   WI_UNARY_RESULT (T2) ymod = umod_trunc (y, width);
   WI_UNARY_RESULT (T1) left = wi::lshift (x, ymod);
-  WI_UNARY_RESULT (T1) right = wi::lrshift (x, wi::sub (width, ymod));
+  WI_UNARY_RESULT (T1) right
+    = wi::lrshift (width != precision ? wi::zext (x, width) : x,
+                  wi::sub (width, ymod));
   if (width != precision)
-    return wi::zext (left, width) | wi::zext (right, width);
+    return wi::zext (left, width) | right;
   return left | right;
 }

@@ -3204,10 +3206,11 @@ wi::rrotate (const T1 &x, const T2 &y, u
   if (width == 0)
     width = precision;
   WI_UNARY_RESULT (T2) ymod = umod_trunc (y, width);
-  WI_UNARY_RESULT (T1) right = wi::lrshift (x, ymod);
+  WI_UNARY_RESULT (T1) right
+    = wi::lrshift (width != precision ? wi::zext (x, width) : x, ymod);
   WI_UNARY_RESULT (T1) left = wi::lshift (x, wi::sub (width, ymod));
   if (width != precision)
-    return wi::zext (left, width) | wi::zext (right, width);
+    return wi::zext (left, width) | right;
   return left | right;
 }

fixes it but I wonder if we shouldn't return if (width != precision) wi::sext
(left | right, width); instead or do that depending on is_sign_extended, or do
the extension in the caller (tree-ssa-ccp.cc).

[Bug tree-optimization/109778] [13/14 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's definitely "odd" API, are you sure it's only used from CCP?  It was
present forever ...

The fix looks good to me of course.

[Bug tree-optimization/109778] [13/14 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:a8302d2a4669984c7c287d12ef5b37cde6699c80

commit r14-602-ga8302d2a4669984c7c287d12ef5b37cde6699c80
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 9 12:10:07 2023 +0200

    tree-ssa-ccp, wide-int: Fix up handling of [LR]ROTATE_EXPR in bitwise ccp
[PR109778]

    The following testcase is miscompiled, because bitwise ccp2 handles
    a rotate with a signed type incorrectly.
    Seems tree-ssa-ccp.cc has the only callers of wi::[lr]rotate with 3
    arguments, all other callers just rotate in the right precision and
    I think work correctly.  ccp works with widest_ints and so rotations
    by the excessive precision certainly don't match what it wants
    when it sees a rotate in some specific bitsize.  Still, if it is
    unsigned rotate and the widest_int is zero extended from width,
    the functions perform left shift and logical right shift on the value
    and then at the end zero extend the result of left shift and uselessly
    also the result of logical right shift and return | of that.
    On the testcase we the signed char rrotate by 4 argument is
    CONSTANT -75 i.e. 0xffffffff....fffffb5 with mask 2.
    The mask is correctly rotated to 0x20, but because the 8-bit constant
    is sign extended to 192-bit one, the logical right shift by 4 doesn't
    yield expected 0xb, but gives 0xfffffffffff....ffffb, and then
    return wi::zext (left, width) | wi::zext (right, width); where left is
    0xfffffff....fb50, so we return 0xfb instead of the expected
    0x5b.

    The following patch fixes that by doing the zero extension in case of
    the right variable before doing wi::lrshift rather than after it.

    Also, wi::[lr]rotate widht width < precision always zero extends
    the result.  I'm afraid it can't do better because it doesn't know
    if it is done for an unsigned or signed type, but the caller in this
    case knows that very well, so I've done the extension based on sgn
    in the caller.  E.g. 0x5b rotated right (or left) by 4 with width 8
    previously gave 0xb5, but sgn == SIGNED in widest_int it should be
    0xffffffff....fffb5 instead.

    2023-05-09  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/109778
            * wide-int.h (wi::lrotate, wi::rrotate): Call wi::lrshift on
            wi::zext (x, width) rather than x if width != precision, rather
            than using wi::zext (right, width) after the shift.
            * tree-ssa-ccp.cc (bit_value_binop): Call wi::ext on the results
            of wi::lrotate or wi::rrotate.

            * gcc.c-torture/execute/pr109778.c: New test.

[Bug tree-optimization/109778] [13/14 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:c2cf2dc988eb93551fa1c01d3f8d73ef21f39dc5

commit r14-603-gc2cf2dc988eb93551fa1c01d3f8d73ef21f39dc5
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 9 12:14:18 2023 +0200

    testsuite: Add further testcase for already fixed PR [PR109778]

    I came up with a testcase which reproduces all the way to r10-7469.
    LTO to avoid early inlining it, so that ccp handles rotates and not
    shifts before they are turned into rotates.

    2023-05-09  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/109778
            * gcc.dg/lto/pr109778_0.c: New test.
            * gcc.dg/lto/pr109778_1.c: New file.

[Bug tree-optimization/109778] [10/11/12/13 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Priority|P3                          |P2
   Target Milestone|13.2                        |10.5
            Summary|[13/14 Regression] Wrong    |[10/11/12/13 Regression]
                   |code at -O1 and above on    |Wrong code at -O1 and above
                   |x86_64-linux-gnu            |on x86_64-linux-gnu
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The above committed testcase fails already starting with
r10-7469-g56f0b32476c0c261c8e08 , so we should fix this also on those release
branches.

[Bug tree-optimization/109778] [10/11/12/13 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-13 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:97f404d53e0f47013afd728e617d03ecc585c6b7

commit r13-7310-g97f404d53e0f47013afd728e617d03ecc585c6b7
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 9 12:10:07 2023 +0200

    tree-ssa-ccp, wide-int: Fix up handling of [LR]ROTATE_EXPR in bitwise ccp
[PR109778]

    The following testcase is miscompiled, because bitwise ccp2 handles
    a rotate with a signed type incorrectly.
    Seems tree-ssa-ccp.cc has the only callers of wi::[lr]rotate with 3
    arguments, all other callers just rotate in the right precision and
    I think work correctly.  ccp works with widest_ints and so rotations
    by the excessive precision certainly don't match what it wants
    when it sees a rotate in some specific bitsize.  Still, if it is
    unsigned rotate and the widest_int is zero extended from width,
    the functions perform left shift and logical right shift on the value
    and then at the end zero extend the result of left shift and uselessly
    also the result of logical right shift and return | of that.
    On the testcase we the signed char rrotate by 4 argument is
    CONSTANT -75 i.e. 0xffffffff....fffffb5 with mask 2.
    The mask is correctly rotated to 0x20, but because the 8-bit constant
    is sign extended to 192-bit one, the logical right shift by 4 doesn't
    yield expected 0xb, but gives 0xfffffffffff....ffffb, and then
    return wi::zext (left, width) | wi::zext (right, width); where left is
    0xfffffff....fb50, so we return 0xfb instead of the expected
    0x5b.

    The following patch fixes that by doing the zero extension in case of
    the right variable before doing wi::lrshift rather than after it.

    Also, wi::[lr]rotate widht width < precision always zero extends
    the result.  I'm afraid it can't do better because it doesn't know
    if it is done for an unsigned or signed type, but the caller in this
    case knows that very well, so I've done the extension based on sgn
    in the caller.  E.g. 0x5b rotated right (or left) by 4 with width 8
    previously gave 0xb5, but sgn == SIGNED in widest_int it should be
    0xffffffff....fffb5 instead.

    2023-05-09  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/109778
            * wide-int.h (wi::lrotate, wi::rrotate): Call wi::lrshift on
            wi::zext (x, width) rather than x if width != precision, rather
            than using wi::zext (right, width) after the shift.
            * tree-ssa-ccp.cc (bit_value_binop): Call wi::ext on the results
            of wi::lrotate or wi::rrotate.

            * gcc.c-torture/execute/pr109778.c: New test.

    (cherry picked from commit a8302d2a4669984c7c287d12ef5b37cde6699c80)

[Bug tree-optimization/109778] [10/11/12/13 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-13 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:5fd2537b36d7ad32e9cb64ddf196105172f919f5

commit r13-7311-g5fd2537b36d7ad32e9cb64ddf196105172f919f5
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 9 12:14:18 2023 +0200

    testsuite: Add further testcase for already fixed PR [PR109778]

    I came up with a testcase which reproduces all the way to r10-7469.
    LTO to avoid early inlining it, so that ccp handles rotates and not
    shifts before they are turned into rotates.

    2023-05-09  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/109778
            * gcc.dg/lto/pr109778_0.c: New test.
            * gcc.dg/lto/pr109778_1.c: New file.

    (cherry picked from commit c2cf2dc988eb93551fa1c01d3f8d73ef21f39dc5)

[Bug tree-optimization/109778] [10/11/12/13 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:2835feb9c29de9167c7af19209065357899b808d

commit r12-9523-g2835feb9c29de9167c7af19209065357899b808d
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 9 12:10:07 2023 +0200

    tree-ssa-ccp, wide-int: Fix up handling of [LR]ROTATE_EXPR in bitwise ccp
[PR109778]

    The following testcase is miscompiled, because bitwise ccp2 handles
    a rotate with a signed type incorrectly.
    Seems tree-ssa-ccp.cc has the only callers of wi::[lr]rotate with 3
    arguments, all other callers just rotate in the right precision and
    I think work correctly.  ccp works with widest_ints and so rotations
    by the excessive precision certainly don't match what it wants
    when it sees a rotate in some specific bitsize.  Still, if it is
    unsigned rotate and the widest_int is zero extended from width,
    the functions perform left shift and logical right shift on the value
    and then at the end zero extend the result of left shift and uselessly
    also the result of logical right shift and return | of that.
    On the testcase we the signed char rrotate by 4 argument is
    CONSTANT -75 i.e. 0xffffffff....fffffb5 with mask 2.
    The mask is correctly rotated to 0x20, but because the 8-bit constant
    is sign extended to 192-bit one, the logical right shift by 4 doesn't
    yield expected 0xb, but gives 0xfffffffffff....ffffb, and then
    return wi::zext (left, width) | wi::zext (right, width); where left is
    0xfffffff....fb50, so we return 0xfb instead of the expected
    0x5b.

    The following patch fixes that by doing the zero extension in case of
    the right variable before doing wi::lrshift rather than after it.

    Also, wi::[lr]rotate widht width < precision always zero extends
    the result.  I'm afraid it can't do better because it doesn't know
    if it is done for an unsigned or signed type, but the caller in this
    case knows that very well, so I've done the extension based on sgn
    in the caller.  E.g. 0x5b rotated right (or left) by 4 with width 8
    previously gave 0xb5, but sgn == SIGNED in widest_int it should be
    0xffffffff....fffb5 instead.

    2023-05-09  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/109778
            * wide-int.h (wi::lrotate, wi::rrotate): Call wi::lrshift on
            wi::zext (x, width) rather than x if width != precision, rather
            than using wi::zext (right, width) after the shift.
            * tree-ssa-ccp.cc (bit_value_binop): Call wi::ext on the results
            of wi::lrotate or wi::rrotate.

            * gcc.c-torture/execute/pr109778.c: New test.

    (cherry picked from commit a8302d2a4669984c7c287d12ef5b37cde6699c80)

[Bug tree-optimization/109778] [10/11/12/13 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:7408a0b93e6f6b3ce9b6be17bb9b5d2307f5ecf1

commit r12-9524-g7408a0b93e6f6b3ce9b6be17bb9b5d2307f5ecf1
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 9 12:14:18 2023 +0200

    testsuite: Add further testcase for already fixed PR [PR109778]

    I came up with a testcase which reproduces all the way to r10-7469.
    LTO to avoid early inlining it, so that ccp handles rotates and not
    shifts before they are turned into rotates.

    2023-05-09  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/109778
            * gcc.dg/lto/pr109778_0.c: New test.
            * gcc.dg/lto/pr109778_1.c: New file.

    (cherry picked from commit c2cf2dc988eb93551fa1c01d3f8d73ef21f39dc5)

[Bug tree-optimization/109778] [10/11/12/13 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:817d1496e17806bdefab1e0fb06abdf56df58cbd

commit r11-10753-g817d1496e17806bdefab1e0fb06abdf56df58cbd
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 9 12:10:07 2023 +0200

    tree-ssa-ccp, wide-int: Fix up handling of [LR]ROTATE_EXPR in bitwise ccp
[PR109778]

    The following testcase is miscompiled, because bitwise ccp2 handles
    a rotate with a signed type incorrectly.
    Seems tree-ssa-ccp.cc has the only callers of wi::[lr]rotate with 3
    arguments, all other callers just rotate in the right precision and
    I think work correctly.  ccp works with widest_ints and so rotations
    by the excessive precision certainly don't match what it wants
    when it sees a rotate in some specific bitsize.  Still, if it is
    unsigned rotate and the widest_int is zero extended from width,
    the functions perform left shift and logical right shift on the value
    and then at the end zero extend the result of left shift and uselessly
    also the result of logical right shift and return | of that.
    On the testcase we the signed char rrotate by 4 argument is
    CONSTANT -75 i.e. 0xffffffff....fffffb5 with mask 2.
    The mask is correctly rotated to 0x20, but because the 8-bit constant
    is sign extended to 192-bit one, the logical right shift by 4 doesn't
    yield expected 0xb, but gives 0xfffffffffff....ffffb, and then
    return wi::zext (left, width) | wi::zext (right, width); where left is
    0xfffffff....fb50, so we return 0xfb instead of the expected
    0x5b.

    The following patch fixes that by doing the zero extension in case of
    the right variable before doing wi::lrshift rather than after it.

    Also, wi::[lr]rotate widht width < precision always zero extends
    the result.  I'm afraid it can't do better because it doesn't know
    if it is done for an unsigned or signed type, but the caller in this
    case knows that very well, so I've done the extension based on sgn
    in the caller.  E.g. 0x5b rotated right (or left) by 4 with width 8
    previously gave 0xb5, but sgn == SIGNED in widest_int it should be
    0xffffffff....fffb5 instead.

    2023-05-09  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/109778
            * wide-int.h (wi::lrotate, wi::rrotate): Call wi::lrshift on
            wi::zext (x, width) rather than x if width != precision, rather
            than using wi::zext (right, width) after the shift.
            * tree-ssa-ccp.c (bit_value_binop): Call wi::ext on the results
            of wi::lrotate or wi::rrotate.

            * gcc.c-torture/execute/pr109778.c: New test.

    (cherry picked from commit a8302d2a4669984c7c287d12ef5b37cde6699c80)

[Bug tree-optimization/109778] [10/11/12/13 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

--- Comment #13 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:5aa649c98dcf58240299029f7dce02ee29ba6296

commit r11-10754-g5aa649c98dcf58240299029f7dce02ee29ba6296
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 9 12:14:18 2023 +0200

    testsuite: Add further testcase for already fixed PR [PR109778]

    I came up with a testcase which reproduces all the way to r10-7469.
    LTO to avoid early inlining it, so that ccp handles rotates and not
    shifts before they are turned into rotates.

    2023-05-09  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/109778
            * gcc.dg/lto/pr109778_0.c: New test.
            * gcc.dg/lto/pr109778_1.c: New file.

    (cherry picked from commit c2cf2dc988eb93551fa1c01d3f8d73ef21f39dc5)

[Bug tree-optimization/109778] [10/11/12/13 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

--- Comment #14 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:f06a5c09287ad4606872403c6f8b01d1fe2f5540

commit r10-11398-gf06a5c09287ad4606872403c6f8b01d1fe2f5540
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 9 12:10:07 2023 +0200

    tree-ssa-ccp, wide-int: Fix up handling of [LR]ROTATE_EXPR in bitwise ccp
[PR109778]

    The following testcase is miscompiled, because bitwise ccp2 handles
    a rotate with a signed type incorrectly.
    Seems tree-ssa-ccp.cc has the only callers of wi::[lr]rotate with 3
    arguments, all other callers just rotate in the right precision and
    I think work correctly.  ccp works with widest_ints and so rotations
    by the excessive precision certainly don't match what it wants
    when it sees a rotate in some specific bitsize.  Still, if it is
    unsigned rotate and the widest_int is zero extended from width,
    the functions perform left shift and logical right shift on the value
    and then at the end zero extend the result of left shift and uselessly
    also the result of logical right shift and return | of that.
    On the testcase we the signed char rrotate by 4 argument is
    CONSTANT -75 i.e. 0xffffffff....fffffb5 with mask 2.
    The mask is correctly rotated to 0x20, but because the 8-bit constant
    is sign extended to 192-bit one, the logical right shift by 4 doesn't
    yield expected 0xb, but gives 0xfffffffffff....ffffb, and then
    return wi::zext (left, width) | wi::zext (right, width); where left is
    0xfffffff....fb50, so we return 0xfb instead of the expected
    0x5b.

    The following patch fixes that by doing the zero extension in case of
    the right variable before doing wi::lrshift rather than after it.

    Also, wi::[lr]rotate widht width < precision always zero extends
    the result.  I'm afraid it can't do better because it doesn't know
    if it is done for an unsigned or signed type, but the caller in this
    case knows that very well, so I've done the extension based on sgn
    in the caller.  E.g. 0x5b rotated right (or left) by 4 with width 8
    previously gave 0xb5, but sgn == SIGNED in widest_int it should be
    0xffffffff....fffb5 instead.

    2023-05-09  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/109778
            * wide-int.h (wi::lrotate, wi::rrotate): Call wi::lrshift on
            wi::zext (x, width) rather than x if width != precision, rather
            than using wi::zext (right, width) after the shift.
            * tree-ssa-ccp.c (bit_value_binop): Call wi::ext on the results
            of wi::lrotate or wi::rrotate.

            * gcc.c-torture/execute/pr109778.c: New test.

    (cherry picked from commit a8302d2a4669984c7c287d12ef5b37cde6699c80)

[Bug tree-optimization/109778] [10/11/12/13 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

--- Comment #15 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:d68d989286340c20bc0f713addf44dc0f0d77ac3

commit r10-11399-gd68d989286340c20bc0f713addf44dc0f0d77ac3
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue May 9 12:14:18 2023 +0200

    testsuite: Add further testcase for already fixed PR [PR109778]

    I came up with a testcase which reproduces all the way to r10-7469.
    LTO to avoid early inlining it, so that ccp handles rotates and not
    shifts before they are turned into rotates.

    2023-05-09  Jakub Jelinek  <jakub@redhat.com>

            PR tree-optimization/109778
            * gcc.dg/lto/pr109778_0.c: New test.
            * gcc.dg/lto/pr109778_1.c: New file.

    (cherry picked from commit c2cf2dc988eb93551fa1c01d3f8d73ef21f39dc5)

[Bug tree-optimization/109778] [10/11/12/13 Regression] Wrong code at -O1 and above on x86_64-linux-gnu

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

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

--- Comment #16 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed.