[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization in SLSR

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

Bill Schmidt  changed:

   What|Removed |Added

 Status|NEW |RESOLVED
 Resolution|--- |FIXED

--- Comment #17 from Bill Schmidt  ---
Now fixed everywhere.

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization in SLSR

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

--- Comment #16 from Bill Schmidt  ---
Author: wschmidt
Date: Tue Jul 25 19:44:10 2017
New Revision: 250544

URL: https://gcc.gnu.org/viewcvs?rev=250544=gcc=rev
Log:
[gcc]

2016-07-25  Bill Schmidt  

Backport from mainline
2016-07-14  Bill Schmidt  

PR tree-optimization/81162
* gimple-ssa-strength-reduction.c (replace_mult_candidate): Don't
replace a negate with an add.

[gcc/testsuite]

2016-07-25  Bill Schmidt  

Backport from mainline
2016-07-14  Bill Schmidt  

PR tree-optimization/81162
* gcc.dg/ubsan/pr81162.c: New file.


Added:
branches/gcc-5-branch/gcc/testsuite/gcc.dg/ubsan/pr81162.c
Modified:
branches/gcc-5-branch/gcc/ChangeLog
branches/gcc-5-branch/gcc/gimple-ssa-strength-reduction.c
branches/gcc-5-branch/gcc/testsuite/ChangeLog

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization in SLSR

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

--- Comment #15 from Bill Schmidt  ---
Author: wschmidt
Date: Tue Jul 25 19:42:36 2017
New Revision: 250543

URL: https://gcc.gnu.org/viewcvs?rev=250543=gcc=rev
Log:
[gcc]

2016-07-25  Bill Schmidt  

Backport from mainline
2016-07-14  Bill Schmidt  

PR tree-optimization/81162
* gimple-ssa-strength-reduction.c (replace_mult_candidate): Don't
replace a negate with an add.

[gcc/testsuite]

2016-07-25  Bill Schmidt  

Backport from mainline
2016-07-14  Bill Schmidt  

PR tree-optimization/81162
* gcc.dg/ubsan/pr81162.c: New file.


Added:
branches/gcc-6-branch/gcc/testsuite/gcc.dg/ubsan/pr81162.c
Modified:
branches/gcc-6-branch/gcc/ChangeLog
branches/gcc-6-branch/gcc/gimple-ssa-strength-reduction.c
branches/gcc-6-branch/gcc/testsuite/ChangeLog

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization in SLSR

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

--- Comment #14 from Bill Schmidt  ---
Author: wschmidt
Date: Tue Jul 25 19:40:50 2017
New Revision: 250542

URL: https://gcc.gnu.org/viewcvs?rev=250542=gcc=rev
Log:
[gcc]

2016-07-25  Bill Schmidt  

Backport from mainline
2016-07-14  Bill Schmidt  

PR tree-optimization/81162
* gimple-ssa-strength-reduction.c (replace_mult_candidate): Don't
replace a negate with an add.

[gcc/testsuite]

2016-07-25  Bill Schmidt  

Backport from mainline
2016-07-14  Bill Schmidt  

PR tree-optimization/81162
* gcc.dg/ubsan/pr81162.c: New file.


Added:
branches/gcc-7-branch/gcc/testsuite/gcc.dg/ubsan/pr81162.c
Modified:
branches/gcc-7-branch/gcc/ChangeLog
branches/gcc-7-branch/gcc/gimple-ssa-strength-reduction.c
branches/gcc-7-branch/gcc/testsuite/ChangeLog

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization in SLSR

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

--- Comment #13 from Bill Schmidt  ---
Author: wschmidt
Date: Mon Jul 17 19:12:11 2017
New Revision: 250284

URL: https://gcc.gnu.org/viewcvs?rev=250284=gcc=rev
Log:
2017-07-17  Bill Schmidt  

PR tree-optimization/81162
* gcc.dg/pr81162.c: Move this to...
* gcc.dg/ubsan/pr81162.c: ...here.


Added:
trunk/gcc/testsuite/gcc.dg/ubsan/pr81162.c
Removed:
trunk/gcc/testsuite/gcc.dg/pr81162.c
Modified:
trunk/gcc/testsuite/ChangeLog

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization in SLSR

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

--- Comment #12 from Bill Schmidt  ---
Right, sorry about the ubsan dependency screwup.  I'll move the test case later
today.

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization in SLSR

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

--- Comment #11 from rguenther at suse dot de  ---
On Mon, 17 Jul 2017, bernd.edlinger at hotmail dot de wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162
> 
> Bernd Edlinger  changed:
> 
>What|Removed |Added
> 
>  CC||bernd.edlinger at hotmail 
> dot de
> 
> --- Comment #10 from Bernd Edlinger  ---
> The test case don't run if gcc-4.6 is host compiler,
> this means it links against the host compiler libubsan.so.0
> which is not really the correct thing to do:
> 
> Setting LD_LIBRARY_PATH to
> :/home/ed/gnu/gcc-build/gcc:/home/ed/gnu/gcc-build/gcc/32:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/./libatomic/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/./libcilkrts/.libs::/home/ed/gnu/gcc-build/gcc:/home/ed/gnu/gcc-build/gcc/32:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/./libatomic/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/./libcilkrts/.libs:/home/ed/gnu/gcc-build/./gmp/.libs:/home/ed/gnu/gcc-build/./prev-gmp/.libs:/home/ed/gnu/gcc-build/./mpfr/src/.libs:/home/ed/gnu/gcc-build/./prev-mpfr/src/.libs:/home/ed/gnu/gcc-build/./mpc/src/.libs:/home/ed/gnu/gcc-build/./prev-mpc/src/.libs:/home/ed/gnu/gcc-build/./isl/.libs:/home/ed/gnu/gcc-build/./prev-isl/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/src/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libsanitizer/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libmpx/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libvtv/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libcilkrts/.libs:/home/ed/gnu/gcc

-build/x86_64-pc-linux-gnu/libssp/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libgomp/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libitm/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libatomic/.libs:/home/ed/gnu/gcc-build/./gcc:/home/ed/gnu/gcc-build/./prev-gcc:/home/ed/gnu/gcc-build/./gmp/.libs:/home/ed/gnu/gcc-build/./prev-gmp/.libs:/home/ed/gnu/gcc-build/./mpfr/src/.libs:/home/ed/gnu/gcc-build/./prev-mpfr/src/.libs:/home/ed/gnu/gcc-build/./mpc/src/.libs:/home/ed/gnu/gcc-build/./prev-mpc/src/.libs:/home/ed/gnu/gcc-build/./isl/.libs:/home/ed/gnu/gcc-build/./prev-isl/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/src/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libsanitizer/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libmpx/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libvtv/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libcilkrts/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libssp/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libgo

mp/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libitm/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libatomic/.libs:/home/ed/gnu/gcc-build/./gcc:/home/ed/gnu/gcc-build/./prev-gcc
> spawn [open ...]^M
> ./pr81162.exe: error while loading shared libraries: libubsan.so.0: cannot 
> open
> shared object file: No such file or directory
> FAIL: gcc.dg/pr81162.c execution test

You need to move it to ubsan/

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization in SLSR

[bernd.edlinger at hotmail dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

Bernd Edlinger  changed:

   What|Removed |Added

 CC||bernd.edlinger at hotmail dot 
de

--- Comment #10 from Bernd Edlinger  ---
The test case don't run if gcc-4.6 is host compiler,
this means it links against the host compiler libubsan.so.0
which is not really the correct thing to do:

Setting LD_LIBRARY_PATH to
:/home/ed/gnu/gcc-build/gcc:/home/ed/gnu/gcc-build/gcc/32:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/./libatomic/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/./libcilkrts/.libs::/home/ed/gnu/gcc-build/gcc:/home/ed/gnu/gcc-build/gcc/32:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/./libatomic/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/./libcilkrts/.libs:/home/ed/gnu/gcc-build/./gmp/.libs:/home/ed/gnu/gcc-build/./prev-gmp/.libs:/home/ed/gnu/gcc-build/./mpfr/src/.libs:/home/ed/gnu/gcc-build/./prev-mpfr/src/.libs:/home/ed/gnu/gcc-build/./mpc/src/.libs:/home/ed/gnu/gcc-build/./prev-mpc/src/.libs:/home/ed/gnu/gcc-build/./isl/.libs:/home/ed/gnu/gcc-build/./prev-isl/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/src/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libsanitizer/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libmpx/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libvtv/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libcilkrts/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libssp/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libgomp/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libitm/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libatomic/.libs:/home/ed/gnu/gcc-build/./gcc:/home/ed/gnu/gcc-build/./prev-gcc:/home/ed/gnu/gcc-build/./gmp/.libs:/home/ed/gnu/gcc-build/./prev-gmp/.libs:/home/ed/gnu/gcc-build/./mpfr/src/.libs:/home/ed/gnu/gcc-build/./prev-mpfr/src/.libs:/home/ed/gnu/gcc-build/./mpc/src/.libs:/home/ed/gnu/gcc-build/./prev-mpc/src/.libs:/home/ed/gnu/gcc-build/./isl/.libs:/home/ed/gnu/gcc-build/./prev-isl/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libstdc++-v3/src/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libsanitizer/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libmpx/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libvtv/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libcilkrts/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libssp/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libgomp/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libitm/.libs:/home/ed/gnu/gcc-build/x86_64-pc-linux-gnu/libatomic/.libs:/home/ed/gnu/gcc-build/./gcc:/home/ed/gnu/gcc-build/./prev-gcc
spawn [open ...]^M
./pr81162.exe: error while loading shared libraries: libubsan.so.0: cannot open
shared object file: No such file or directory
FAIL: gcc.dg/pr81162.c execution test

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization in SLSR

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

Bill Schmidt  changed:

   What|Removed |Added

  Known to work||8.0

--- Comment #9 from Bill Schmidt  ---
Fixed in trunk so far.  Need to verify that backports are needed, but I suspect
they are.

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization in SLSR

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

--- Comment #8 from Bill Schmidt  ---
Author: wschmidt
Date: Fri Jul 14 18:06:45 2017
New Revision: 250212

URL: https://gcc.gnu.org/viewcvs?rev=250212=gcc=rev
Log:
[gcc]

2016-07-14  Bill Schmidt  

PR tree-optimization/81162
* gimple-ssa-strength-reduction.c (replace_mult_candidate): Don't
replace a negate with an add.

[gcc/testsuite]

2016-07-14  Bill Schmidt  

PR tree-optimization/81162
* gcc.dg/pr81162.c: New file.


Added:
trunk/gcc/testsuite/gcc.dg/pr81162.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/gimple-ssa-strength-reduction.c
trunk/gcc/testsuite/ChangeLog

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization in SLSR

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

--- Comment #7 from Bill Schmidt  ---
This case comes up when we're going to replace a NEGATE_EXPR with a PLUS_EXPR
or MINUS_EXPR.  This is another case of an unprofitable replacement that should
be avoided anyway.  So I think the following fix is what we need:

Index: gcc/gimple-ssa-strength-reduction.c
===
--- gcc/gimple-ssa-strength-reduction.c (revision 249846)
+++ gcc/gimple-ssa-strength-reduction.c (working copy)
@@ -2082,13 +2082,14 @@ replace_mult_candidate (slsr_cand_t c, tree basis_
  types but allows for safe negation without twisted logic.  */
   if (wi::fits_shwi_p (bump)
   && bump.to_shwi () != HOST_WIDE_INT_MIN
-  /* It is not useful to replace casts, copies, or adds of
+  /* It is not useful to replace casts, copies, negates, or adds of
 an SSA name and a constant.  */
   && cand_code != SSA_NAME
   && !CONVERT_EXPR_CODE_P (cand_code)
   && cand_code != PLUS_EXPR
   && cand_code != POINTER_PLUS_EXPR
-  && cand_code != MINUS_EXPR)
+  && cand_code != MINUS_EXPR
+  && cand_code != NEGATE_EXPR)
 {
   enum tree_code code = PLUS_EXPR;
   tree bump_tree;

This fixes the particular test.  I have to head out on vacation now, but I will
regstrap this and submit it when I get back if there are no objections.

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization in SLSR

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

Bill Schmidt  changed:

   What|Removed |Added

   Assignee|unassigned at gcc dot gnu.org  |wschmidt at gcc dot 
gnu.org

--- Comment #6 from Bill Schmidt  ---
Hm, thought we had all of these overflow cases sorted out long ago.  I'll have
a look.  I'll be out on vacation shortly so this may not get fixed until second
week of July if it's not immediately obvious.

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

Richard Biener  changed:

   What|Removed |Added

 Status|ASSIGNED|NEW
 CC||rguenth at gcc dot gnu.org,
   ||wschmidt at gcc dot gnu.org
   Assignee|rguenth at gcc dot gnu.org |unassigned at gcc dot 
gnu.org

--- Comment #5 from Richard Biener  ---
So we go i1 && i2 -> FAIL.  After VRP1:

  # RANGE [0, 255] NONZERO 255
  _2 = (int) uc.0_1;
...
  if (i1 && i2)
   [100.00%] [count: INV]:
  # RANGE [0, 1]
  # iftmp.1_14 = PHI <1(3), 0(4)>
  # RANGE [0, 1] NONZERO 1
  _7 = (int) iftmp.1_14;
  # RANGE [0, 256] NONZERO 511
  _10 = _7 + _2;
  # RANGE [-256, 0]
  _11 = 0 - _10;
  _12 = _11 ^ -21096;
  # RANGE ~[2147483648, 18446744071562067967]
  _13 = (long long unsigned int) _12;
  if (_13 <= 9031239389974324562)
OK
  else
FAIL

the unfolded 0 - _10 gets cleaned up by forwprop3 to

  # RANGE [-256, 0]
  _11 = -_10;

PRE then takes the opportunity to optimize this to

   [100.00%] [count: INV]:
  # RANGE [0, 1]
  # iftmp.1_14 = PHI <1(4), 0(3), 0(2)>
  # RANGE [-256, 0]
  # prephitmp_27 = PHI <_26(4), _3(3), _3(2)>
  _12 = prephitmp_27 ^ -21096;
  # RANGE ~[2147483648, 18446744071562067967]
  _13 = (long long unsigned int) _12;
  if (_13 <= 9031239389974324562)

which still looks correct to me.  Then slsr seems to fold

   [100.00%] [count: INV]:
  uc.0_1 = uc;
  # RANGE [0, 255] NONZERO 255
  _2 = (int) uc.0_1;
  # RANGE [-255, 0]
  _3 = -_2;
  # RANGE [2147483392, 2147483647] NONZERO 2147483647
  _17 = _3 + 2147483647;
...
[25.00%] [count: INV]:
   _24 = _2 + 1;
-  _26 = -_24;
+  _26 = _17 - -2147483648;

somehow which looks really odd... and from which VRP2 rightfully derives

_26: [2147483647, +INF]

Strength reduction candidate vector:

  1  [2] _3 = -_2;
 MULT : (_2 + 0) * -1 : int
 basis: 0  dependent: 2  sibling: 0
 next-interp: 0  dead-savings: 0

  2  [2] _17 = _3 + 2147483647;
 MULT : (_2 + -2147483647) * -1 : int
 basis: 1  dependent: 4  sibling: 0
 next-interp: 0  dead-savings: 0

I think this is an invalid candidate given undefined integer overflow
semantics.
We have to be very careful here or emit all new expressions in unsigned
arithmetic.

  3  [4] _24 = _2 + 1;
 ADD  : _2 + (1 * 1) : int
 basis: 0  dependent: 0  sibling: 0
 next-interp: 0  dead-savings: 0

  4  [4] _26 = -_24;
 MULT : (_2 + 1) * -1 : int
 basis: 2  dependent: 0  sibling: 0
 next-interp: 0  dead-savings: 4

that looks ok but we seem to end up relating this to [2]:

Strength reduction candidate chains:

_2 -> 1 -> 4 -> 3 -> 2
_12 -> 5 -> 6


Processing dependency tree rooted at 1.
Replacing: _26 = -_24;
With: _26 = _17 - -2147483648;

cost-wise we see that _24 is eliminated by the transform I guess.

Bill?

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

Richard Biener  changed:

   What|Removed |Added

 Status|NEW |ASSIGNED
   Assignee|unassigned at gcc dot gnu.org  |rguenth at gcc dot 
gnu.org

--- Comment #4 from Richard Biener  ---
I'll have a looksee.

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

--- Comment #3 from Marek Polacek  ---
And the difference is that with -fsanitize=integer-divide-by-zero we'll do
this:
5257   if (sanitize_flags_p ((SANITIZE_SHIFT
5258  | SANITIZE_DIVIDE | SANITIZE_FLOAT_DIVIDE))
5259   && !processing_template_decl 
5260   && (doing_div_or_mod || doing_shift))
5261 {
5262   /* OP0 and/or OP1 might have side-effects.  */
5263   op0 = cp_save_expr (op0);
5264   op1 = cp_save_expr (op1);

so in .original there's
(void) (s = (short int) (NON_LVALUE_EXPR >))
instead of
(void) (s = (short int) ~(unsigned short) uc)

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

--- Comment #2 from Marek Polacek  ---
-fsanitize=integer-divide-by-zero is what seems to trigger this.

[Bug tree-optimization/81162] [8 Regression] UBSAN switch triggers incorrect optimization

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81162

Marek Polacek  changed:

   What|Removed |Added

 Status|UNCONFIRMED |NEW
   Last reconfirmed||2017-06-22
 CC||mpolacek at gcc dot gnu.org
   Target Milestone|--- |8.0
Summary|UBSAN switch triggers   |[8 Regression] UBSAN switch
   |incorrect optimization  |triggers incorrect
   ||optimization
 Ever confirmed|0   |1

--- Comment #1 from Marek Polacek  ---
Confirmed, started with r247578.