Re: [PATCH 9/9] cse.c selftests

Re: [PATCH 9/9] cse.c selftests

[Bernd Edlinger]

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Hi David,

> I attempted to create a reproducer for PR 71779; however I'm not yet
> able to replicate the bogus cse reported there via the test case.

Thanks, this is just awesome.  I immediately had to try your patch.

The main reason for PR 71779 was that this

(insn 1047 1046 1048 (set (reg:DI 481)
        (subreg:DI (reg/f:SI 479) 0)) y.c:12702 -1
     (nil))

got transformed into that:

(insn 1047 1046 1048 107 (set (reg/f:DI 481)
        (subreg:DI (reg/f:SI 477) 0)) y.c:12702 50 {*movdi_aarch64}
     (expr_list:REG_DEAD (reg/f:SI 479)
        (nil)))

Note the "/f at reg 481.  This together with the fact that -mabi=ilp32
makes Pmode != ptr_mode caused a cascade of different errors.

For the wrong transformation in combine to happen, we need 
Pmode = DImode, ptr_mode=SImode, and REG_POINTER(x)
is true, but only REG_POINTER is really wrong.

First the good news.  The unit test does actually work, but not only
on aarch even without -mabi=ilp32, but also on i386.  All that's
missing is a check that we don't get a reg/f here:

test_pr71779 ()
{
  /* Only run this tests for target==aarch64.  */
#ifndef GCC_AARCH64_H
#ifndef I386_OPTS_H
  return;
#endif
#endif
  ...
  tem = cse_main (get_insns (), max_reg_num ());
  ASSERT_EQ (0, tem);
  ASSERT_FALSE (REG_POINTER (SET_DEST (PATTERN (get_insn_by_uid (1047)))));
}

Test fails on aarch64 and i386 if I revert the attached patch for PR 71779,
and passes again, if I apply the patch again.  Excellent!

Attached for your reference, the original patch file from PR 71779.

/home/ed/gnu/gcc-build-aarch64/./gcc/xgcc -B/home/ed/gnu/gcc-build-aarch64/./gcc/ -xc -S -c /dev/null -fself-test
../../gcc-trunk/gcc/cse.c:7872: test_pr71779: FAIL: ASSERT_FALSE (((__extension__ ({ __typeof (((((PATTERN (get_insn_by_uid (1047)))->u.fld[0]).rt_rtx))) const _rtx = (((((PATTERN (get_insn_by_uid (1047)))->u.fld[0]).rt_rtx))); if (((enum rtx_code) (_rtx)->code) != REG) rtl_check_failed_flag ("REG_POINTER", _rtx, "../../gcc-trunk/gcc/cse.c", 7872, __FUNCTION__); _rtx; })->frame_related)))
In function 'test_1':
cc1: internal compiler error: in fail, at selftest.c:46
0x11bdd8e selftest::fail(selftest::location const&, char const*)
	../../gcc-trunk/gcc/selftest.c:46
0x10944ec test_pr71779
	../../gcc-trunk/gcc/cse.c:7872
0x10944ec selftest::cse_c_tests()
	../../gcc-trunk/gcc/cse.c:7881
0x11631fe selftest::run_tests()
	../../gcc-trunk/gcc/selftest-run-tests.c:68
0xb36242 toplev::run_self_tests()
	../../gcc-trunk/gcc/toplev.c:2074

I noticed, that ASSERT_FALSE does expand the macros, which makes
the output a bit hard to read.

One minor thing, an unrelated test did fail before the cse test got executed on my aarch64,
so I just commented that part out:


/home/ed/gnu/gcc-build-aarch64/./gcc/xgcc -B/home/ed/gnu/gcc-build-aarch64/./gcc/ -xc -S -c /dev/null -fself-test
../../gcc-trunk/gcc/read-rtl-function.c:923: test_loading_dump_fragment_2: FAIL: ASSERT_TRUE ((((lhs)->frame_related)))
In function 'test_1':
cc1: internal compiler error: in fail, at selftest.c:46
0x11be8ae selftest::fail(selftest::location const&, char const*)
	../../gcc-trunk/gcc/selftest.c:46
0x115577a test_loading_dump_fragment_2
	../../gcc-trunk/gcc/read-rtl-function.c:923
0x1157cce selftest::read_rtl_function_c_tests()
	../../gcc-trunk/gcc/read-rtl-function.c:1183
0x1163d14 selftest::run_tests()
	../../gcc-trunk/gcc/selftest-run-tests.c:66
0xb36262 toplev::run_self_tests()
	../../gcc-trunk/gcc/toplev.c:2074


the aarch64 was configured this way:

../gcc-trunk/configure --prefix=/home/ed/gnu/aarch64-unknown-elf --target=aarch64-unknown-elf --enable-languages=c --disable-shared --disable-threads --disable-libssp --disable-libgomp --disable-libquadmath --disable-libatomic


Maybe one last comment on your patch itself, could you please move
the unit test cases in extra unit test files, or even a self-test tree?


Thanks
Bernd.

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[-- Type: text/x-patch; name="patch-pr71779.diff", Size: 960 bytes --]

2016-08-04  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	PR rtl-optimization/71779
	* emit-rtl.c (set_reg_attrs_from_value): Only propagate REG_POINTER,
	if the value was sign-extended according to POINTERS_EXTEND_UNSIGNED
	or if it was truncated.

Index: gcc/emit-rtl.c
===================================================================
--- gcc/emit-rtl.c	(revision 238915)
+++ gcc/emit-rtl.c	(working copy)
@@ -1156,7 +1156,11 @@ set_reg_attrs_from_value (rtx reg, rtx x)
     {
 #if defined(POINTERS_EXTEND_UNSIGNED)
       if (((GET_CODE (x) == SIGN_EXTEND && POINTERS_EXTEND_UNSIGNED)
-	   || (GET_CODE (x) != SIGN_EXTEND && ! POINTERS_EXTEND_UNSIGNED))
+	   || (GET_CODE (x) == ZERO_EXTEND && ! POINTERS_EXTEND_UNSIGNED)
+	   || (paradoxical_subreg_p (x)
+	       && ! (SUBREG_PROMOTED_VAR_P (x)
+		     && SUBREG_CHECK_PROMOTED_SIGN (x,
+						    POINTERS_EXTEND_UNSIGNED))))
 	  && !targetm.have_ptr_extend ())
 	can_be_reg_pointer = false;
 #endif

Re: [PATCH 9/9] cse.c selftests

[Jeff Law]

On 09/09/2016 07:28 AM, Bernd Edlinger wrote:
> Hi David,
>
>> I attempted to create a reproducer for PR 71779; however I'm not yet
>> able to replicate the bogus cse reported there via the test case.
>
> Thanks, this is just awesome.  I immediately had to try your patch.
I'd pointed David at 71779 because it was such a good example of the 
kind of thing we'd like to be able to avoid by using the self-testing 
framework.

ie, someone says "hey, I don't think this code is needed anymore, let's 
remove it" and hope nothing breaks.  We do have the regression suite now 
which helps considerably, but changes early in the optimization pipeline 
may easily mask problems introduced much later in the pipeline.

With David's work, the goal is to be able to hand off reasonable hunks 
of RTL to internal routines and see how they manipulate the RTL and 
verify correctness.  Essentially bypassing everything except the 
routines in question that we want to test.

There's a lot of unknowns in this space and I'm hoping that David's work 
will shed some light on how we can build a robust RTL test framework.


>
> The main reason for PR 71779 was that this
>
> (insn 1047 1046 1048 (set (reg:DI 481)
>         (subreg:DI (reg/f:SI 479) 0)) y.c:12702 -1
>      (nil))
>
> got transformed into that:
>
> (insn 1047 1046 1048 107 (set (reg/f:DI 481)
>         (subreg:DI (reg/f:SI 477) 0)) y.c:12702 50 {*movdi_aarch64}
>      (expr_list:REG_DEAD (reg/f:SI 479)
>         (nil)))
>
> Note the "/f at reg 481.  This together with the fact that -mabi=ilp32
> makes Pmode != ptr_mode caused a cascade of different errors.
>
> For the wrong transformation in combine to happen, we need
> Pmode = DImode, ptr_mode=SImode, and REG_POINTER(x)
> is true, but only REG_POINTER is really wrong.
>
> First the good news.  The unit test does actually work, but not only
> on aarch even without -mabi=ilp32, but also on i386.  All that's
> missing is a check that we don't get a reg/f here:
Sweet.  This starts to touch on some of those unanswered questions -- 
while 71779 was visibly only failing on aarch64, can we build tests 
which are ultimately target independent?  I suspected that would be the 
case for 71779, but whether or not that will hold in general remains to 
be seen.


>
> test_pr71779 ()
> {
>   /* Only run this tests for target==aarch64.  */
> #ifndef GCC_AARCH64_H
> #ifndef I386_OPTS_H
>   return;
> #endif
> #endif
>   ...
>   tem = cse_main (get_insns (), max_reg_num ());
>   ASSERT_EQ (0, tem);
>   ASSERT_FALSE (REG_POINTER (SET_DEST (PATTERN (get_insn_by_uid (1047)))));
> }
>

>
> One minor thing, an unrelated test did fail before the cse test got executed on my aarch64,
> so I just commented that part out:
>
>
> /home/ed/gnu/gcc-build-aarch64/./gcc/xgcc -B/home/ed/gnu/gcc-build-aarch64/./gcc/ -xc -S -c /dev/null -fself-test
> ../../gcc-trunk/gcc/read-rtl-function.c:923: test_loading_dump_fragment_2: FAIL: ASSERT_TRUE ((((lhs)->frame_related)))
> In function 'test_1':
> cc1: internal compiler error: in fail, at selftest.c:46
> 0x11be8ae selftest::fail(selftest::location const&, char const*)
> 	../../gcc-trunk/gcc/selftest.c:46
> 0x115577a test_loading_dump_fragment_2
> 	../../gcc-trunk/gcc/read-rtl-function.c:923
> 0x1157cce selftest::read_rtl_function_c_tests()
> 	../../gcc-trunk/gcc/read-rtl-function.c:1183
> 0x1163d14 selftest::run_tests()
> 	../../gcc-trunk/gcc/selftest-run-tests.c:66
> 0xb36262 toplev::run_self_tests()
> 	../../gcc-trunk/gcc/toplev.c:2074
>
>
> the aarch64 was configured this way:
>
> ../gcc-trunk/configure --prefix=/home/ed/gnu/aarch64-unknown-elf --target=aarch64-unknown-elf --enable-languages=c --disable-shared --disable-threads --disable-libssp --disable-libgomp --disable-libquadmath --disable-libatomic
>
>
> Maybe one last comment on your patch itself, could you please move
> the unit test cases in extra unit test files, or even a self-test tree?
That's one of the things we debated for quite a while earlier.  For now 
they're living in the source files which they're testing.  Whether or 
not that's best remains to be seen.

jeff

Re: [PATCH 9/9] cse.c selftests

[Bernd Edlinger]

On 09/10/16 01:11, Jeff Law wrote:
>> First the good news.  The unit test does actually work, but not only
>> on aarch even without -mabi=ilp32, but also on i386.  All that's
>> missing is a check that we don't get a reg/f here:
> Sweet.  This starts to touch on some of those unanswered questions --
> while 71779 was visibly only failing on aarch64, can we build tests
> which are ultimately target independent?  I suspected that would be the
> case for 71779, but whether or not that will hold in general remains to
> be seen.
>

Things can be target dependent, like Pmode, ptr_mode as in this case.
And target hooks can detect the cheat...

So I would not be surprised, that a test case like that needs really to
be verified on each arch, if it is actually able to detect the failure,
because if not it just risks a bootstrap failure nothing more.

>>
>> Maybe one last comment on your patch itself, could you please move
>> the unit test cases in extra unit test files, or even a self-test tree?
> That's one of the things we debated for quite a while earlier.  For now
> they're living in the source files which they're testing.  Whether or
> not that's best remains to be seen.
>

Yes, and for the initial version that is perfectly OK.

I would not have been able to write down the test case, but this looks
like a very powerful method.

The more examples there are the easier it will be to create new ones.

If there are going to be more test cases, it would be better to
have them separated in single files, like in the testsuite.

If there is a standard way how to link the test cases in the
back-end, like with static constructors, adding each test case
to a list, without knowing in advance which ones it will be.

Then we could boot-strap as usual, without risking a
boot-strap failure if a single test case fails.

Then when the test suite runs, it can compile 100 test cases
at a time, link that into a special cc1, and execute that,
then the next 100 test cases, and so on.  And the tests
can specify the supported target in a dg-do like target
comment.

Sorry if that has already been discussed somewhere.


Thanks
Bernd.

Re: [PATCH 9/9] cse.c selftests

[Jeff Law]

On 09/16/2016 03:19 PM, David Malcolm wrote:
>
>> When possible I don't think we want the tests to be target specific.
>> Hmm, I'm probably about to argue for Bernd's work...  The 71779
>> testcase
>> is a great example -- it uses high/lo_sum.  Not all targets support
>> that
>> -- as long as we don't try to recognize those insns we're likely OK,
>> but
>> that seems fragile long term.  Having an idealized target means we
>> can
>> ignore much of these issues.
>
> An alternative would be to pick a specific target for each test.
It's an alternative, but not one I particularly like since those tests 
won't be consistently run.  With an abstracted target like Bernd 
suggests we ought to be able to make most tests work with the abstracted 
target and minimize the number of truely target specific tests.


>> So I'm real curious, what happens if you run this RTL selftest under
>> valgrind?  I have the sneaking suspicion that we'll start doing some
>> uninitialized memory reads.
>
> I'm seeing various leaks (an htab within linemap_init for all of the
> line_table fixtures), but no uninitialized reads.
Wow.  I must say I'm surprised.  Good news though.


>>   +
>>> +  /* Dump taken from comment 2 of PR 71779, of
>>> +     "...the relevant memory access coming out of expand"
>>> +     with basic block IDs added, and prev/next insns set to
>>> +     0 at ends.  */
>>> +  const char *input_dump
>>> +    = (";; MEM[(struct isl_obj *)&obj1] = &isl_obj_map_vtable;\n"
>>> +       "(insn 1045 0 1046 2 (set (reg:SI 480)\n"
>>> +       "        (high:SI (symbol_ref:SI (\"isl_obj_map_vtable\")
>>> [flags 0xc0] <var_decl 0x7fa0363ea240 isl_obj_map_vtable>)))
>>> y.c:12702 -1\n"
>>> +       "     (nil))\n"
>>> +       "(insn 1046 1045 1047 2 (set (reg/f:SI 479)\n"
>>> +       "        (lo_sum:SI (reg:SI 480)\n"
>>> +       "            (symbol_ref:SI (\"isl_obj_map_vtable\") [flags
>>> 0xc0] <var_decl 0x7fa0363ea240 isl_obj_map_vtable>))) y.c:12702
>>> -1\n"
>>> +       "     (expr_list:REG_EQUAL (symbol_ref:SI
>>> (\"isl_obj_map_vtable\") [flags 0xc0] <var_decl 0x7fa0363ea240
>>> isl_obj_map_vtable>)\n"
>>> +       "        (nil)))\n"
>>> +       "(insn 1047 1046 1048 2 (set (reg:DI 481)\n"
>>> +       "        (subreg:DI (reg/f:SI 479) 0)) y.c:12702 -1\n"
>>> +       "     (nil))\n"
>>> +       "(insn 1048 1047 1049 2 (set (zero_extract:DI (reg/v:DI 191
>>> [ obj1D.17368 ])\n"
>>> +       "            (const_int 32 [0x20])\n"
>>> +       "            (const_int 0 [0]))\n"
>>> +       "        (reg:DI 481)) y.c:12702 -1\n"
>>> +       "     (nil))\n"
>> So looking at this just makes my head hurt.  Escaping, lots of
>> quotes,
>> unnecessary things in the dump, etc.  The question I would have is
>> why
>> not have a file with the dump and read the file?
>
> (nods)
>
> Seems like I need to add a mechanism for telling the selftests which
> directory to load the tests relative to.
What about putting them inside the appropriate gcc.target directories? 
We could have one for the "generic" target assuming we build something 
like that, the others could live in their target specific directory.


jeff

Re: [PATCH 9/9] cse.c selftests

[David Malcolm]

On Fri, 2016-09-16 at 14:26 -0600, Jeff Law wrote:
> On 09/08/2016 06:30 PM, David Malcolm wrote:
> > This patch uses rtl_dump_test to start building out a test suite
> > for cse.
> > 
> > I attempted to create a reproducer for PR 71779; however I'm not
> > yet
> > able to replicate the bogus cse reported there via the test case.
> > 
> > gcc/ChangeLog:
> > 	* cse.c: Include selftest.h and selftest-rtl.h.
> > 	(selftest::test_simple_cse): New function.
> > 	(selftest::test_pr71779): New function.
> > 	(selftest::cse_c_tests): New function.
> > 	* selftest-run-tests.c (selftest::run_tests): Call
> > 	selftest::cse_c_tests.
> > 	* selftest.h (selftest::cse_c_tests): New decl.
> So as I look at this, the first thing that comes to mind is whether
> or 
> not to refine the dump output.
> 
> There's a lot of useless crap in there that really only helps folks
> that 
> sitting inside a debugger dumping hunks of RTL (I'm thinking 
> specifically about the pointers back to tree nodes for DECLs).  Those
> addresses are useless in other contexts.
> 
> When possible I don't think we want the tests to be target specific. 
> Hmm, I'm probably about to argue for Bernd's work...  The 71779
> testcase 
> is a great example -- it uses high/lo_sum.  Not all targets support
> that 
> -- as long as we don't try to recognize those insns we're likely OK,
> but 
> that seems fragile long term.  Having an idealized target means we
> can 
> ignore much of these issues.

An alternative would be to pick a specific target for each test.


> > ---
> >  gcc/cse.c                | 109
> > +++++++++++++++++++++++++++++++++++++++++++++++
> >  gcc/selftest-run-tests.c |   1 +
> >  gcc/selftest.h           |   1 +
> >  3 files changed, 111 insertions(+)
> > 
> > diff --git a/gcc/cse.c b/gcc/cse.c
> > index 0bfd7ff..f4f06fe 100644
> > --- a/gcc/cse.c
> > +++ b/gcc/cse.c
> > @@ -41,6 +41,8 @@ along with GCC; see the file COPYING3.  If not
> > see
> >  #include "tree-pass.h"
> >  #include "dbgcnt.h"
> >  #include "rtl-iter.h"
> > +#include "selftest.h"
> > +#include "selftest-rtl.h"
> > 
> >  #ifndef LOAD_EXTEND_OP
> >  #define LOAD_EXTEND_OP(M) UNKNOWN
> > @@ -7773,3 +7775,110 @@ make_pass_cse_after_global_opts
> > (gcc::context *ctxt)
> >  {
> >    return new pass_cse_after_global_opts (ctxt);
> >  }
> > +
> > +#if CHECKING_P
> > +
> > +namespace selftest {
> > +
> > +/* Selftests for CSE.  */
> > +
> > +/* Simple test of eliminating a redundant (reg + 1) computation
> > +   i.e. that:
> > +     r101 = r100 + 1;
> > +     r102 = r100 + 1; <<< common subexpression
> > +     *r103 = r101 * r102;
> > +   can be CSE-ed to:
> > +     r101 = r100 + 1;
> > +     r102 = r101; <<< replaced
> > +     *r103 = r101 * r102;
> > +   by cse_main.  */
> So I'm real curious, what happens if you run this RTL selftest under 
> valgrind?  I have the sneaking suspicion that we'll start doing some 
> uninitialized memory reads.

I'm seeing various leaks (an htab within linemap_init for all of the
line_table fixtures), but no uninitialized reads.

> > +
> > +static void
> > +test_simple_cse ()
> > +{
> > +  /* Only run this tests for i386.  */
> > +#ifndef I386_OPTS_H
> > +  return;
> > +#endif
> > +
> > +  const char *input_dump
> > +    = (/* "r101 = r100 + 1;" */
> > +       "(insn 1 0 2 2 (set (reg:SI 101)\n"
> > +       "                   (plus:SI (reg:SI 100)\n"
> > +       "                            (const_int 1 [0x1]))) -1
> > (nil))\n"
> > +       /* "r102 = r100 + 1;" */
> > +       "(insn 2 1 3 2 (set (reg:SI 102)\n"
> > +       "                   (plus:SI (reg:SI 100)\n"
> > +       "                            (const_int 1 [0x1]))) -1
> > (nil))\n"
> > +       /* "*r103 = r101 * r102;" */
> > +       "(insn 3 2 0 2 (set (mem:SI (reg:SI 103) [1 i+0 S4 A32])\n"
> > +       "                   (mult:SI (reg:SI 101) (reg:SI 102))) -1
> > (nil))\n"
> > +       );
> I don't think we need to comment each RTL insn for those which are so
> obvious.  It just adds to the visual clutter.

This may have been more for my benefit; I'm still relatively new to RTL
:)

>   +
> > +  /* Dump taken from comment 2 of PR 71779, of
> > +     "...the relevant memory access coming out of expand"
> > +     with basic block IDs added, and prev/next insns set to
> > +     0 at ends.  */
> > +  const char *input_dump
> > +    = (";; MEM[(struct isl_obj *)&obj1] = &isl_obj_map_vtable;\n"
> > +       "(insn 1045 0 1046 2 (set (reg:SI 480)\n"
> > +       "        (high:SI (symbol_ref:SI (\"isl_obj_map_vtable\")
> > [flags 0xc0] <var_decl 0x7fa0363ea240 isl_obj_map_vtable>)))
> > y.c:12702 -1\n"
> > +       "     (nil))\n"
> > +       "(insn 1046 1045 1047 2 (set (reg/f:SI 479)\n"
> > +       "        (lo_sum:SI (reg:SI 480)\n"
> > +       "            (symbol_ref:SI (\"isl_obj_map_vtable\") [flags
> > 0xc0] <var_decl 0x7fa0363ea240 isl_obj_map_vtable>))) y.c:12702 
> > -1\n"
> > +       "     (expr_list:REG_EQUAL (symbol_ref:SI
> > (\"isl_obj_map_vtable\") [flags 0xc0] <var_decl 0x7fa0363ea240
> > isl_obj_map_vtable>)\n"
> > +       "        (nil)))\n"
> > +       "(insn 1047 1046 1048 2 (set (reg:DI 481)\n"
> > +       "        (subreg:DI (reg/f:SI 479) 0)) y.c:12702 -1\n"
> > +       "     (nil))\n"
> > +       "(insn 1048 1047 1049 2 (set (zero_extract:DI (reg/v:DI 191
> > [ obj1D.17368 ])\n"
> > +       "            (const_int 32 [0x20])\n"
> > +       "            (const_int 0 [0]))\n"
> > +       "        (reg:DI 481)) y.c:12702 -1\n"
> > +       "     (nil))\n"
> So looking at this just makes my head hurt.  Escaping, lots of
> quotes, 
> unnecessary things in the dump, etc.  The question I would have is
> why 
> not have a file with the dump and read the file?
 
(nods)

Seems like I need to add a mechanism for telling the selftests which
directory to load the tests relative to.

Re: [PATCH 9/9] cse.c selftests

[Jeff Law]

On 09/08/2016 06:30 PM, David Malcolm wrote:
> This patch uses rtl_dump_test to start building out a test suite
> for cse.
>
> I attempted to create a reproducer for PR 71779; however I'm not yet
> able to replicate the bogus cse reported there via the test case.
>
> gcc/ChangeLog:
> 	* cse.c: Include selftest.h and selftest-rtl.h.
> 	(selftest::test_simple_cse): New function.
> 	(selftest::test_pr71779): New function.
> 	(selftest::cse_c_tests): New function.
> 	* selftest-run-tests.c (selftest::run_tests): Call
> 	selftest::cse_c_tests.
> 	* selftest.h (selftest::cse_c_tests): New decl.
So as I look at this, the first thing that comes to mind is whether or 
not to refine the dump output.

There's a lot of useless crap in there that really only helps folks that 
sitting inside a debugger dumping hunks of RTL (I'm thinking 
specifically about the pointers back to tree nodes for DECLs).  Those 
addresses are useless in other contexts.

When possible I don't think we want the tests to be target specific. 
Hmm, I'm probably about to argue for Bernd's work...  The 71779 testcase 
is a great example -- it uses high/lo_sum.  Not all targets support that 
-- as long as we don't try to recognize those insns we're likely OK, but 
that seems fragile long term.  Having an idealized target means we can 
ignore much of these issues.



> ---
>  gcc/cse.c                | 109 +++++++++++++++++++++++++++++++++++++++++++++++
>  gcc/selftest-run-tests.c |   1 +
>  gcc/selftest.h           |   1 +
>  3 files changed, 111 insertions(+)
>
> diff --git a/gcc/cse.c b/gcc/cse.c
> index 0bfd7ff..f4f06fe 100644
> --- a/gcc/cse.c
> +++ b/gcc/cse.c
> @@ -41,6 +41,8 @@ along with GCC; see the file COPYING3.  If not see
>  #include "tree-pass.h"
>  #include "dbgcnt.h"
>  #include "rtl-iter.h"
> +#include "selftest.h"
> +#include "selftest-rtl.h"
>
>  #ifndef LOAD_EXTEND_OP
>  #define LOAD_EXTEND_OP(M) UNKNOWN
> @@ -7773,3 +7775,110 @@ make_pass_cse_after_global_opts (gcc::context *ctxt)
>  {
>    return new pass_cse_after_global_opts (ctxt);
>  }
> +
> +#if CHECKING_P
> +
> +namespace selftest {
> +
> +/* Selftests for CSE.  */
> +
> +/* Simple test of eliminating a redundant (reg + 1) computation
> +   i.e. that:
> +     r101 = r100 + 1;
> +     r102 = r100 + 1; <<< common subexpression
> +     *r103 = r101 * r102;
> +   can be CSE-ed to:
> +     r101 = r100 + 1;
> +     r102 = r101; <<< replaced
> +     *r103 = r101 * r102;
> +   by cse_main.  */
So I'm real curious, what happens if you run this RTL selftest under 
valgrind?  I have the sneaking suspicion that we'll start doing some 
uninitialized memory reads.


> +
> +static void
> +test_simple_cse ()
> +{
> +  /* Only run this tests for i386.  */
> +#ifndef I386_OPTS_H
> +  return;
> +#endif
> +
> +  const char *input_dump
> +    = (/* "r101 = r100 + 1;" */
> +       "(insn 1 0 2 2 (set (reg:SI 101)\n"
> +       "                   (plus:SI (reg:SI 100)\n"
> +       "                            (const_int 1 [0x1]))) -1 (nil))\n"
> +       /* "r102 = r100 + 1;" */
> +       "(insn 2 1 3 2 (set (reg:SI 102)\n"
> +       "                   (plus:SI (reg:SI 100)\n"
> +       "                            (const_int 1 [0x1]))) -1 (nil))\n"
> +       /* "*r103 = r101 * r102;" */
> +       "(insn 3 2 0 2 (set (mem:SI (reg:SI 103) [1 i+0 S4 A32])\n"
> +       "                   (mult:SI (reg:SI 101) (reg:SI 102))) -1 (nil))\n"
> +       );
I don't think we need to comment each RTL insn for those which are so 
obvious.  It just adds to the visual clutter.


  +
> +  /* Dump taken from comment 2 of PR 71779, of
> +     "...the relevant memory access coming out of expand"
> +     with basic block IDs added, and prev/next insns set to
> +     0 at ends.  */
> +  const char *input_dump
> +    = (";; MEM[(struct isl_obj *)&obj1] = &isl_obj_map_vtable;\n"
> +       "(insn 1045 0 1046 2 (set (reg:SI 480)\n"
> +       "        (high:SI (symbol_ref:SI (\"isl_obj_map_vtable\") [flags 0xc0] <var_decl 0x7fa0363ea240 isl_obj_map_vtable>))) y.c:12702 -1\n"
> +       "     (nil))\n"
> +       "(insn 1046 1045 1047 2 (set (reg/f:SI 479)\n"
> +       "        (lo_sum:SI (reg:SI 480)\n"
> +       "            (symbol_ref:SI (\"isl_obj_map_vtable\") [flags 0xc0] <var_decl 0x7fa0363ea240 isl_obj_map_vtable>))) y.c:12702 -1\n"
> +       "     (expr_list:REG_EQUAL (symbol_ref:SI (\"isl_obj_map_vtable\") [flags 0xc0] <var_decl 0x7fa0363ea240 isl_obj_map_vtable>)\n"
> +       "        (nil)))\n"
> +       "(insn 1047 1046 1048 2 (set (reg:DI 481)\n"
> +       "        (subreg:DI (reg/f:SI 479) 0)) y.c:12702 -1\n"
> +       "     (nil))\n"
> +       "(insn 1048 1047 1049 2 (set (zero_extract:DI (reg/v:DI 191 [ obj1D.17368 ])\n"
> +       "            (const_int 32 [0x20])\n"
> +       "            (const_int 0 [0]))\n"
> +       "        (reg:DI 481)) y.c:12702 -1\n"
> +       "     (nil))\n"
So looking at this just makes my head hurt.  Escaping, lots of quotes, 
unnecessary things in the dump, etc.  The question I would have is why 
not have a file with the dump and read the file?

[PATCH 9/9] cse.c selftests

[David Malcolm]

This patch uses rtl_dump_test to start building out a test suite
for cse.

I attempted to create a reproducer for PR 71779; however I'm not yet
able to replicate the bogus cse reported there via the test case.

gcc/ChangeLog:
	* cse.c: Include selftest.h and selftest-rtl.h.
	(selftest::test_simple_cse): New function.
	(selftest::test_pr71779): New function.
	(selftest::cse_c_tests): New function.
	* selftest-run-tests.c (selftest::run_tests): Call
	selftest::cse_c_tests.
	* selftest.h (selftest::cse_c_tests): New decl.
---
 gcc/cse.c                | 109 +++++++++++++++++++++++++++++++++++++++++++++++
 gcc/selftest-run-tests.c |   1 +
 gcc/selftest.h           |   1 +
 3 files changed, 111 insertions(+)

diff --git a/gcc/cse.c b/gcc/cse.c
index 0bfd7ff..f4f06fe 100644
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -41,6 +41,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-pass.h"
 #include "dbgcnt.h"
 #include "rtl-iter.h"
+#include "selftest.h"
+#include "selftest-rtl.h"
 
 #ifndef LOAD_EXTEND_OP
 #define LOAD_EXTEND_OP(M) UNKNOWN
@@ -7773,3 +7775,110 @@ make_pass_cse_after_global_opts (gcc::context *ctxt)
 {
   return new pass_cse_after_global_opts (ctxt);
 }
+
+#if CHECKING_P
+
+namespace selftest {
+
+/* Selftests for CSE.  */
+
+/* Simple test of eliminating a redundant (reg + 1) computation
+   i.e. that:
+     r101 = r100 + 1;
+     r102 = r100 + 1; <<< common subexpression
+     *r103 = r101 * r102;
+   can be CSE-ed to:
+     r101 = r100 + 1;
+     r102 = r101; <<< replaced
+     *r103 = r101 * r102;
+   by cse_main.  */
+
+static void
+test_simple_cse ()
+{
+  /* Only run this tests for i386.  */
+#ifndef I386_OPTS_H
+  return;
+#endif
+
+  const char *input_dump
+    = (/* "r101 = r100 + 1;" */
+       "(insn 1 0 2 2 (set (reg:SI 101)\n"
+       "                   (plus:SI (reg:SI 100)\n"
+       "                            (const_int 1 [0x1]))) -1 (nil))\n"
+       /* "r102 = r100 + 1;" */
+       "(insn 2 1 3 2 (set (reg:SI 102)\n"
+       "                   (plus:SI (reg:SI 100)\n"
+       "                            (const_int 1 [0x1]))) -1 (nil))\n"
+       /* "*r103 = r101 * r102;" */
+       "(insn 3 2 0 2 (set (mem:SI (reg:SI 103) [1 i+0 S4 A32])\n"
+       "                   (mult:SI (reg:SI 101) (reg:SI 102))) -1 (nil))\n"
+       );
+  rtl_dump_test t (input_dump, 100);
+  dataflow_test df_test;
+
+  int tem;
+  tem = cse_main (get_insns (), max_reg_num ());
+  ASSERT_EQ (0, tem);
+
+  /* Verify that insn 2's SET_SRC has been replaced with
+     the SET_DEST of insn 1.  */
+  ASSERT_EQ (SET_DEST (PATTERN (get_insn_by_uid (1))),
+	     SET_SRC (PATTERN (get_insn_by_uid (2))));
+}
+
+/* Towards a regression test for PR 71779.  */
+
+static void
+test_pr71779 ()
+{
+  /* Only run this tests for target==aarch64.  */
+#ifndef GCC_AARCH64_H
+  return;
+#endif
+
+  /* Dump taken from comment 2 of PR 71779, of
+     "...the relevant memory access coming out of expand"
+     with basic block IDs added, and prev/next insns set to
+     0 at ends.  */
+  const char *input_dump
+    = (";; MEM[(struct isl_obj *)&obj1] = &isl_obj_map_vtable;\n"
+       "(insn 1045 0 1046 2 (set (reg:SI 480)\n"
+       "        (high:SI (symbol_ref:SI (\"isl_obj_map_vtable\") [flags 0xc0] <var_decl 0x7fa0363ea240 isl_obj_map_vtable>))) y.c:12702 -1\n"
+       "     (nil))\n"
+       "(insn 1046 1045 1047 2 (set (reg/f:SI 479)\n"
+       "        (lo_sum:SI (reg:SI 480)\n"
+       "            (symbol_ref:SI (\"isl_obj_map_vtable\") [flags 0xc0] <var_decl 0x7fa0363ea240 isl_obj_map_vtable>))) y.c:12702 -1\n"
+       "     (expr_list:REG_EQUAL (symbol_ref:SI (\"isl_obj_map_vtable\") [flags 0xc0] <var_decl 0x7fa0363ea240 isl_obj_map_vtable>)\n"
+       "        (nil)))\n"
+       "(insn 1047 1046 1048 2 (set (reg:DI 481)\n"
+       "        (subreg:DI (reg/f:SI 479) 0)) y.c:12702 -1\n"
+       "     (nil))\n"
+       "(insn 1048 1047 1049 2 (set (zero_extract:DI (reg/v:DI 191 [ obj1D.17368 ])\n"
+       "            (const_int 32 [0x20])\n"
+       "            (const_int 0 [0]))\n"
+       "        (reg:DI 481)) y.c:12702 -1\n"
+       "     (nil))\n"
+       /* Extra insn, to avoid all of the above from being deleted by DCE.  */
+       "(insn 1049 1048 0 2 (set (mem:DI (reg:DI 191) [1 i+0 S4 A32])\n"
+       "                         (const_int 1 [0x1])) -1 (nil))\n");
+
+  rtl_dump_test t (input_dump);
+  dataflow_test df_test;
+
+  int tem;
+  tem = cse_main (get_insns (), max_reg_num ());
+  ASSERT_EQ (0, tem);
+}
+
+/* Run all of the selftests within this file.  */
+
+void
+cse_c_tests ()
+{
+  test_simple_cse ();
+  test_pr71779 ();
+}
+
+} // namespace selftest
+#endif /* CHECKING_P */
diff --git a/gcc/selftest-run-tests.c b/gcc/selftest-run-tests.c
index 015572c..5fdfb42 100644
--- a/gcc/selftest-run-tests.c
+++ b/gcc/selftest-run-tests.c
@@ -65,6 +65,7 @@ selftest::run_tests ()
   rtl_tests_c_tests ();
   read_rtl_function_c_tests ();
   df_core_c_tests ();
+  cse_c_tests ();
 
   /* Higher-level tests, or for components that other selftests don't
      rely on.  */
diff --git a/gcc/selftest.h b/gcc/selftest.h
index 6ad6c88..c0dc862 100644
--- a/gcc/selftest.h
+++ b/gcc/selftest.h
@@ -191,6 +191,7 @@ extern void forcibly_ggc_collect ();
    alphabetical order.  */
 extern void bitmap_c_tests ();
 extern void combine_c_tests ();
+extern void cse_c_tests ();
 extern void df_core_c_tests ();
 extern void diagnostic_c_tests ();
 extern void diagnostic_show_locus_c_tests ();
-- 
1.8.5.3