Re: [PATCH][GCC 7] Remove broken path in extract_bit_field_1

[Richard Biener]

On Mon, Apr 4, 2016 at 3:33 PM, Jakub Jelinek  wrote:
> On Mon, Apr 04, 2016 at 03:27:23PM +0200, Richard Biener wrote:
>> It ICEs in
>>
>> /space/rguenther/src/svn/trunk/gcc/testsuite/gcc.target/i386/pr37870.c:19:1:
>> internal compiler error: in subreg_get_info, at rtlanal.c:3695
>> 0xddee5a subreg_get_info(unsigned int, machine_mode, unsigned int,
>> machine_mode, subreg_info*)
>> /space/rguenther/src/svn/trunk/gcc/rtlanal.c:3695
>> 0xddf12b simplify_subreg_regno(unsigned int, machine_mode, unsigned int,
>> machine_mode)
>> /space/rguenther/src/svn/trunk/gcc/rtlanal.c:3808
>> 0xd8bc7a simplifiable_subregs(subreg_shape const&)
>> /space/rguenther/src/svn/trunk/gcc/reginfo.c:1234
>> 0xd8be1d record_subregs_of_mode
>> /space/rguenther/src/svn/trunk/gcc/reginfo.c:1294
>> 0xd8c246 init_subregs_of_mode()
>> /space/rguenther/src/svn/trunk/gcc/reginfo.c:1348
>> 0xc1a55c init_costs
>> /space/rguenther/src/svn/trunk/gcc/ira-costs.c:2187
>>
>> which is
>>
>>   /* This should always pass, otherwise we don't know how to verify
>>  the constraint.  These conditions may be relaxed but
>>  subreg_regno_offset would need to be redesigned.  */
>>   gcc_assert ((GET_MODE_SIZE (xmode) % GET_MODE_SIZE (ymode)) == 0);
>
> So perhaps either validate_subreg should check the same thing, or
> the extraction could check this.
> Anyway, I don't have anything against removing that hunk from
> extract_bit_field_1 for GCC7.

Now committed.

Richard.

> Jakub

Re: [PATCH][GCC 7] Remove broken path in extract_bit_field_1

[Jakub Jelinek]

On Mon, Apr 04, 2016 at 03:27:23PM +0200, Richard Biener wrote:
> It ICEs in
> 
> /space/rguenther/src/svn/trunk/gcc/testsuite/gcc.target/i386/pr37870.c:19:1: 
> internal compiler error: in subreg_get_info, at rtlanal.c:3695
> 0xddee5a subreg_get_info(unsigned int, machine_mode, unsigned int, 
> machine_mode, subreg_info*)
> /space/rguenther/src/svn/trunk/gcc/rtlanal.c:3695
> 0xddf12b simplify_subreg_regno(unsigned int, machine_mode, unsigned int, 
> machine_mode)
> /space/rguenther/src/svn/trunk/gcc/rtlanal.c:3808
> 0xd8bc7a simplifiable_subregs(subreg_shape const&)
> /space/rguenther/src/svn/trunk/gcc/reginfo.c:1234
> 0xd8be1d record_subregs_of_mode
> /space/rguenther/src/svn/trunk/gcc/reginfo.c:1294
> 0xd8c246 init_subregs_of_mode()
> /space/rguenther/src/svn/trunk/gcc/reginfo.c:1348
> 0xc1a55c init_costs
> /space/rguenther/src/svn/trunk/gcc/ira-costs.c:2187
> 
> which is
> 
>   /* This should always pass, otherwise we don't know how to verify
>  the constraint.  These conditions may be relaxed but
>  subreg_regno_offset would need to be redesigned.  */
>   gcc_assert ((GET_MODE_SIZE (xmode) % GET_MODE_SIZE (ymode)) == 0);

So perhaps either validate_subreg should check the same thing, or
the extraction could check this.
Anyway, I don't have anything against removing that hunk from
extract_bit_field_1 for GCC7.

Jakub

Re: [PATCH][GCC 7] Remove broken path in extract_bit_field_1

[Richard Biener]

On Mon, 4 Apr 2016, Jakub Jelinek wrote:

> On Mon, Apr 04, 2016 at 03:10:34PM +0200, Richard Biener wrote:
> > On Mon, 4 Apr 2016, Jakub Jelinek wrote:
> > 
> > > On Mon, Apr 04, 2016 at 02:56:51PM +0200, Richard Biener wrote:
> > > > The testcase gcc.target/i386/pr37870.c will already ICE with that
> > > > patch, so no additional testcase.
> > > 
> > > In theory you could validate_subreg first and use that code if validation
> > > went ok, otherwise go through memory.
> > > But I admit I don't have anything in particular in mind where it would
> > > trigger this code and the subreg would successfully validate.
> > 
> > Not sure if it would help as that has
> > 
> >   /* ??? Similarly, e.g. with (subreg:DF (reg:TI)).  Though 
> > store_bit_field
> >  is the culprit here, and not the backends.  */
> >   else if (osize >= UNITS_PER_WORD && isize >= osize)
> > ;
> > 
> > and thus we'd return true anyway for (subreg:XF (reg:TI) 0)
> 
> If XFmode subreg of TImode reg passes validation, where does it ICE then?

It ICEs in

/space/rguenther/src/svn/trunk/gcc/testsuite/gcc.target/i386/pr37870.c:19:1: 
internal compiler error: in subreg_get_info, at rtlanal.c:3695
0xddee5a subreg_get_info(unsigned int, machine_mode, unsigned int, 
machine_mode, subreg_info*)
/space/rguenther/src/svn/trunk/gcc/rtlanal.c:3695
0xddf12b simplify_subreg_regno(unsigned int, machine_mode, unsigned int, 
machine_mode)
/space/rguenther/src/svn/trunk/gcc/rtlanal.c:3808
0xd8bc7a simplifiable_subregs(subreg_shape const&)
/space/rguenther/src/svn/trunk/gcc/reginfo.c:1234
0xd8be1d record_subregs_of_mode
/space/rguenther/src/svn/trunk/gcc/reginfo.c:1294
0xd8c246 init_subregs_of_mode()
/space/rguenther/src/svn/trunk/gcc/reginfo.c:1348
0xc1a55c init_costs
/space/rguenther/src/svn/trunk/gcc/ira-costs.c:2187

which is

  /* This should always pass, otherwise we don't know how to verify
 the constraint.  These conditions may be relaxed but
 subreg_regno_offset would need to be redesigned.  */
  gcc_assert ((GET_MODE_SIZE (xmode) % GET_MODE_SIZE (ymode)) == 0);

Richard.

Re: [PATCH][GCC 7] Remove broken path in extract_bit_field_1

[Jakub Jelinek]

On Mon, Apr 04, 2016 at 03:10:34PM +0200, Richard Biener wrote:
> On Mon, 4 Apr 2016, Jakub Jelinek wrote:
> 
> > On Mon, Apr 04, 2016 at 02:56:51PM +0200, Richard Biener wrote:
> > > The testcase gcc.target/i386/pr37870.c will already ICE with that
> > > patch, so no additional testcase.
> > 
> > In theory you could validate_subreg first and use that code if validation
> > went ok, otherwise go through memory.
> > But I admit I don't have anything in particular in mind where it would
> > trigger this code and the subreg would successfully validate.
> 
> Not sure if it would help as that has
> 
>   /* ??? Similarly, e.g. with (subreg:DF (reg:TI)).  Though 
> store_bit_field
>  is the culprit here, and not the backends.  */
>   else if (osize >= UNITS_PER_WORD && isize >= osize)
> ;
> 
> and thus we'd return true anyway for (subreg:XF (reg:TI) 0)

If XFmode subreg of TImode reg passes validation, where does it ICE then?

Jakub

Re: [PATCH][GCC 7] Remove broken path in extract_bit_field_1

[Richard Biener]

On Mon, 4 Apr 2016, Jakub Jelinek wrote:

> On Mon, Apr 04, 2016 at 02:56:51PM +0200, Richard Biener wrote:
> > The testcase gcc.target/i386/pr37870.c will already ICE with that
> > patch, so no additional testcase.
> 
> In theory you could validate_subreg first and use that code if validation
> went ok, otherwise go through memory.
> But I admit I don't have anything in particular in mind where it would
> trigger this code and the subreg would successfully validate.

Not sure if it would help as that has

  /* ??? Similarly, e.g. with (subreg:DF (reg:TI)).  Though 
store_bit_field
 is the culprit here, and not the backends.  */
  else if (osize >= UNITS_PER_WORD && isize >= osize)
;

and thus we'd return true anyway for (subreg:XF (reg:TI) 0)

Richard.

> > 2016-04-04  Richard Biener  
> > 
> > PR middle-end/37870
> > * expmed.c (extract_bit_field_1): Remove broken case
> > using a wider MODE_INT mode.
> > 
> > Index: gcc/expmed.c
> > ===
> > --- gcc/expmed.c(revision 234708)
> > +++ gcc/expmed.c(working copy)
> > @@ -1647,17 +1647,6 @@ extract_bit_field_1 (rtx str_rtx, unsign
> > if (GET_CODE (op0) == SUBREG)
> >   op0 = force_reg (imode, op0);
> >   }
> > -   else if (REG_P (op0))
> > - {
> > -   rtx reg, subreg;
> > -   imode = smallest_mode_for_size (GET_MODE_BITSIZE (GET_MODE (op0)),
> > -   MODE_INT);
> > -   reg = gen_reg_rtx (imode);
> > -   subreg = gen_lowpart_SUBREG (GET_MODE (op0), reg);
> > -   emit_move_insn (subreg, op0);
> > -   op0 = reg;
> > -   bitnum += SUBREG_BYTE (subreg) * BITS_PER_UNIT;
> > - }
> > else
> >   {
> > HOST_WIDE_INT size = GET_MODE_SIZE (GET_MODE (op0));
> 
>   Jakub
> 
> 

-- 
Richard Biener 
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 
21284 (AG Nuernberg)

Re: [PATCH][GCC 7] Remove broken path in extract_bit_field_1

[Jakub Jelinek]

On Mon, Apr 04, 2016 at 02:56:51PM +0200, Richard Biener wrote:
> The testcase gcc.target/i386/pr37870.c will already ICE with that
> patch, so no additional testcase.

In theory you could validate_subreg first and use that code if validation
went ok, otherwise go through memory.
But I admit I don't have anything in particular in mind where it would
trigger this code and the subreg would successfully validate.

> 2016-04-04  Richard Biener  
> 
>   PR middle-end/37870
>   * expmed.c (extract_bit_field_1): Remove broken case
>   using a wider MODE_INT mode.
> 
> Index: gcc/expmed.c
> ===
> --- gcc/expmed.c  (revision 234708)
> +++ gcc/expmed.c  (working copy)
> @@ -1647,17 +1647,6 @@ extract_bit_field_1 (rtx str_rtx, unsign
>   if (GET_CODE (op0) == SUBREG)
> op0 = force_reg (imode, op0);
> }
> - else if (REG_P (op0))
> -   {
> - rtx reg, subreg;
> - imode = smallest_mode_for_size (GET_MODE_BITSIZE (GET_MODE (op0)),
> - MODE_INT);
> - reg = gen_reg_rtx (imode);
> - subreg = gen_lowpart_SUBREG (GET_MODE (op0), reg);
> - emit_move_insn (subreg, op0);
> - op0 = reg;
> - bitnum += SUBREG_BYTE (subreg) * BITS_PER_UNIT;
> -   }
>   else
> {
>   HOST_WIDE_INT size = GET_MODE_SIZE (GET_MODE (op0));

Jakub