[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

Peter Bergner  changed:

   What|Removed |Added

 Status|RESOLVED|CLOSED

--- Comment #20 from Peter Bergner  ---
Closing as fixed.

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

Peter Bergner  changed:

   What|Removed |Added

 Status|ASSIGNED|RESOLVED
 Resolution|--- |FIXED

--- Comment #19 from Peter Bergner  ---
Patch committed.

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

Peter Bergner  changed:

   What|Removed |Added

 Status|NEW |ASSIGNED
URL||https://gcc.gnu.org/ml/gcc-
   ||patches/2018-01/msg00216.ht
   ||ml
   Target Milestone|--- |8.0

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

--- Comment #18 from Peter Bergner  ---
Author: bergner
Date: Thu Jan  4 14:36:35 2018
New Revision: 256250

URL: https://gcc.gnu.org/viewcvs?rev=256250=gcc=rev
Log:
PR target/83387
* config/rs6000/rs6000.c (rs6000_discover_homogeneous_aggregate): Do
not
allow arguments in FP registers if TARGET_HARD_FLOAT is false.

Modified:
trunk/gcc/ChangeLog
trunk/gcc/config/rs6000/rs6000.c

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

Peter Bergner  changed:

   What|Removed |Added

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

--- Comment #17 from Peter Bergner  ---
(In reply to Segher Boessenkool from comment #16)
>> How do we want to continue with this PR? Close it as WONTFIX or apply the
>> patch and close it as FIXED?
> 
> If it works, and doesn't regress anything, it is pre-approved.  So please
> test it on powerp64le-linux (gcc112 for example).

Sorry, I'm just getting back up to speed after the long holiday.  I can kick
off a regression test and then commit when it comes back clean.  Thanks.

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[segher at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

--- Comment #16 from Segher Boessenkool  ---
> > > --- gcc/config/rs6000/rs6000.c(revision 255700)
> > > +++ gcc/config/rs6000/rs6000.c(working copy)
> > > @@ -11095,7 +11095,8 @@ rs6000_discover_homogeneous_aggregate (m
> > >   homogeneous aggregates; these types are handled via the
> > >   targetm.calls.split_complex_arg mechanism.  Complex types
> > >   can be elements of homogeneous aggregates, however.  */
> > > -  if (DEFAULT_ABI == ABI_ELFv2 && type && AGGREGATE_TYPE_P (type))
> > > +  if (TARGET_HARD_FLOAT && DEFAULT_ABI == ABI_ELFv2 && type
> > > +  && AGGREGATE_TYPE_P (type))
> > >  {
> > >machine_mode field_mode = VOIDmode;
> > >int field_count = rs6000_aggregate_candidate (type, _mode);
> > > 
> > > 
> > > 
> > 
> > With this patch I can build an Ada compiler with a -m64 and -msoft-float
> > multilib.
> 
> How do we want to continue with this PR? Close it as WONTFIX or apply the
> patch and close it as FIXED?

If it works, and doesn't regress anything, it is pre-approved.  So please
test it on powerp64le-linux (gcc112 for example).

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[sebastian.hu...@embedded-brains.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

--- Comment #15 from Sebastian Huber  ---
(In reply to Sebastian Huber from comment #14)
> (In reply to Peter Bergner from comment #13)
> > (In reply to Sebastian Huber from comment #12)
> > > (In reply to Peter Bergner from comment #9)
> > > [...]
> > > > Here, you can see that on ELFv2, we always assume HW FP regs are 
> > > > avialable,
> > > > because we're forcing usage of HW FP registers (FP_ARG_RETURN, ie, f1, 
> > > > aka
> > > > reg 33).  I'm afraid that are going to be a *LOT* of these assumptions
> > > > builtin into the backend and tracking them all down and fixing them is 
> > > > not
> > > > going to be easy.  That's why I asked earlier, if you really really 
> > > > need to
> > > > disable HW FP for your builds.  If you do, then good luck to you finding
> > > > them all.
> > > 
> > > Thanks for your investigations. I removed the 64-bit soft-float multilib.
> > 
> > I can't promise this is all you need, but does the following patch help?
> > 
> > Index: gcc/config/rs6000/rs6000.c
> > ===
> > --- gcc/config/rs6000/rs6000.c  (revision 255700)
> > +++ gcc/config/rs6000/rs6000.c  (working copy)
> > @@ -11095,7 +11095,8 @@ rs6000_discover_homogeneous_aggregate (m
> >   homogeneous aggregates; these types are handled via the
> >   targetm.calls.split_complex_arg mechanism.  Complex types
> >   can be elements of homogeneous aggregates, however.  */
> > -  if (DEFAULT_ABI == ABI_ELFv2 && type && AGGREGATE_TYPE_P (type))
> > +  if (TARGET_HARD_FLOAT && DEFAULT_ABI == ABI_ELFv2 && type
> > +  && AGGREGATE_TYPE_P (type))
> >  {
> >machine_mode field_mode = VOIDmode;
> >int field_count = rs6000_aggregate_candidate (type, _mode);
> > 
> > 
> > 
> 
> With this patch I can build an Ada compiler with a -m64 and -msoft-float
> multilib.

How do we want to continue with this PR? Close it as WONTFIX or apply the patch
and close it as FIXED?

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[sebastian.hu...@embedded-brains.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

--- Comment #14 from Sebastian Huber  ---
(In reply to Peter Bergner from comment #13)
> (In reply to Sebastian Huber from comment #12)
> > (In reply to Peter Bergner from comment #9)
> > [...]
> > > Here, you can see that on ELFv2, we always assume HW FP regs are 
> > > avialable,
> > > because we're forcing usage of HW FP registers (FP_ARG_RETURN, ie, f1, aka
> > > reg 33).  I'm afraid that are going to be a *LOT* of these assumptions
> > > builtin into the backend and tracking them all down and fixing them is not
> > > going to be easy.  That's why I asked earlier, if you really really need 
> > > to
> > > disable HW FP for your builds.  If you do, then good luck to you finding
> > > them all.
> > 
> > Thanks for your investigations. I removed the 64-bit soft-float multilib.
> 
> I can't promise this is all you need, but does the following patch help?
> 
> Index: gcc/config/rs6000/rs6000.c
> ===
> --- gcc/config/rs6000/rs6000.c(revision 255700)
> +++ gcc/config/rs6000/rs6000.c(working copy)
> @@ -11095,7 +11095,8 @@ rs6000_discover_homogeneous_aggregate (m
>   homogeneous aggregates; these types are handled via the
>   targetm.calls.split_complex_arg mechanism.  Complex types
>   can be elements of homogeneous aggregates, however.  */
> -  if (DEFAULT_ABI == ABI_ELFv2 && type && AGGREGATE_TYPE_P (type))
> +  if (TARGET_HARD_FLOAT && DEFAULT_ABI == ABI_ELFv2 && type
> +  && AGGREGATE_TYPE_P (type))
>  {
>machine_mode field_mode = VOIDmode;
>int field_count = rs6000_aggregate_candidate (type, _mode);
> 
> 
> 

With this patch I can build an Ada compiler with a -m64 and -msoft-float
multilib.

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

--- Comment #13 from Peter Bergner  ---
(In reply to Sebastian Huber from comment #12)
> (In reply to Peter Bergner from comment #9)
> [...]
> > Here, you can see that on ELFv2, we always assume HW FP regs are avialable,
> > because we're forcing usage of HW FP registers (FP_ARG_RETURN, ie, f1, aka
> > reg 33).  I'm afraid that are going to be a *LOT* of these assumptions
> > builtin into the backend and tracking them all down and fixing them is not
> > going to be easy.  That's why I asked earlier, if you really really need to
> > disable HW FP for your builds.  If you do, then good luck to you finding
> > them all.
> 
> Thanks for your investigations. I removed the 64-bit soft-float multilib.

I can't promise this is all you need, but does the following patch help?

Index: gcc/config/rs6000/rs6000.c
===
--- gcc/config/rs6000/rs6000.c  (revision 255700)
+++ gcc/config/rs6000/rs6000.c  (working copy)
@@ -11095,7 +11095,8 @@ rs6000_discover_homogeneous_aggregate (m
  homogeneous aggregates; these types are handled via the
  targetm.calls.split_complex_arg mechanism.  Complex types
  can be elements of homogeneous aggregates, however.  */
-  if (DEFAULT_ABI == ABI_ELFv2 && type && AGGREGATE_TYPE_P (type))
+  if (TARGET_HARD_FLOAT && DEFAULT_ABI == ABI_ELFv2 && type
+  && AGGREGATE_TYPE_P (type))
 {
   machine_mode field_mode = VOIDmode;
   int field_count = rs6000_aggregate_candidate (type, _mode);



> Would it be possible to generate a proper ICE with a user friendly error
> message if someone uses -msoft-float on this target?

We cannot, because we support building the 64-bit linux kernel (both ELFv1 and
ELFv2 - ie, BE and LE) using -msoft-float.  The reason they don't see a problem
is that the linux kernel doesn't have any explicit FP code/type usage in its C
source files.

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[sebastian.hu...@embedded-brains.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

--- Comment #12 from Sebastian Huber  ---
(In reply to Peter Bergner from comment #9)
[...]
> Here, you can see that on ELFv2, we always assume HW FP regs are avialable,
> because we're forcing usage of HW FP registers (FP_ARG_RETURN, ie, f1, aka
> reg 33).  I'm afraid that are going to be a *LOT* of these assumptions
> builtin into the backend and tracking them all down and fixing them is not
> going to be easy.  That's why I asked earlier, if you really really need to
> disable HW FP for your builds.  If you do, then good luck to you finding
> them all.

Thanks for your investigations. I removed the 64-bit soft-float multilib.

Would it be possible to generate a proper ICE with a user friendly error
message if someone uses -msoft-float on this target?

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[sh at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

--- Comment #11 from sh at gcc dot gnu.org ---
Author: sh
Date: Tue Dec 19 08:20:05 2017
New Revision: 255810

URL: https://gcc.gnu.org/viewcvs?rev=255810=gcc=rev
Log:
RTEMS/PowerPC: Remove 64-bit soft-float multilib

gcc/
PR target/83387
* config/rs6000/t-rtems (MULTILIB_REQUIRED): Remove 64-bit soft-float
multilib.

Modified:
branches/gcc-7-branch/gcc/ChangeLog
branches/gcc-7-branch/gcc/config/rs6000/t-rtems

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[sh at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

--- Comment #10 from sh at gcc dot gnu.org ---
Author: sh
Date: Tue Dec 19 08:16:34 2017
New Revision: 255809

URL: https://gcc.gnu.org/viewcvs?rev=255809=gcc=rev
Log:
RTEMS/PowerPC: Remove 64-bit soft-float multilib

gcc/
PR target/83387
* config/rs6000/t-rtems (MULTILIB_REQUIRED): Remove 64-bit soft-float
multilib.


Modified:
trunk/gcc/ChangeLog
trunk/gcc/config/rs6000/t-rtems

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

--- Comment #9 from Peter Bergner  ---
...and the parallel with the  FP reg use (33 and 34) come from:

expand_call():
  valreg = hard_function_value (build_pointer_type (rettype),
fndecl, NULL, (pass == 0));

  hard_function_value():
val = targetm.calls.function_value (valtype, func ? func : fntype,
outgoing);

rs6000_function_value():

  /* The ELFv2 ABI returns homogeneous VFP aggregates in registers.  */
  if (rs6000_discover_homogeneous_aggregate (mode, valtype, _mode,
_elts))
{
  int first_reg, n_regs;

  if (SCALAR_FLOAT_MODE_NOT_VECTOR_P (elt_mode))
{
  /* _Decimal128 must use even/odd register pairs.  */
  first_reg = (elt_mode == TDmode) ? FP_ARG_RETURN + 1 : FP_ARG_RETURN;
  n_regs = (GET_MODE_SIZE (elt_mode) + 7) >> 3;
}
  else
{
  first_reg = ALTIVEC_ARG_RETURN;
  n_regs = 1;
}

  return rs6000_parallel_return (mode, n_elts, elt_mode, first_reg,
n_regs);
}

Here, you can see that on ELFv2, we always assume HW FP regs are avialable,
because we're forcing usage of HW FP registers (FP_ARG_RETURN, ie, f1, aka reg
33).  I'm afraid that are going to be a *LOT* of these assumptions builtin into
the backend and tracking them all down and fixing them is not going to be easy.
 That's why I asked earlier, if you really really need to disable HW FP for
your builds.  If you do, then good luck to you finding them all.

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[bergner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

Peter Bergner  changed:

   What|Removed |Added

 Status|UNCONFIRMED |NEW
   Last reconfirmed||2017-12-18
 Ever confirmed|0   |1

--- Comment #8 from Peter Bergner  ---
Building a debug ada compiler, I see the same thing.  This does look like
you're hitting an assumption that 64-bit compiles assume they have hw FP.  If I
add -fdump-rtl-expand-all to the compile command and then look at the generated
dump file, I see:

;; Generating RTL for gimple basic block 2

;; P.0 = ada.text_io.complex_aux.get (file_2(D), width_3(D));

(insn 7 6 8 (set (reg:DI 4 4)
(reg/v:DI 134 [ widthD.3010 ])) "a-ticoio.adb":58 -1
 (nil))

(insn 8 7 9 (set (reg:DI 3 3)
(reg/v/f:DI 133 [ fileD.3006 ])) "a-ticoio.adb":58 -1
 (nil))

(call_insn 9 8 10 (parallel [
(set (parallel:TI [
(expr_list:REG_DEP_TRUE (reg:DF 33 1)
(const_int 0 [0]))
(expr_list:REG_DEP_TRUE (reg:DF 34 2)
(const_int 8 [0x8]))
])
(call (mem:SI (symbol_ref:DI ("ada__text_io__complex_aux__get")
[flags 0x41] ) [0
ada__text_io__complex_aux__getD.3060 S4 A8])
(const_int 0 [0])))
(clobber (reg:DI 65 lr))
]) "a-ticoio.adb":58 -1
 (expr_list:REG_EH_REGION (const_int 2 [0x2])
(expr_list:REG_CALL_DECL (symbol_ref:DI
("ada__text_io__complex_aux__get") [flags 0x41] )
(nil)))
(expr_list (use (reg:DI 2 2))
(expr_list:DI (use (reg:DI 3 3))
(expr_list:SI (use (reg:DI 4 4))
(nil)

(insn 10 9 11 (set (reg:DF 135)
(reg:DF 33 1)) "a-ticoio.adb":58 -1
 (nil))

(insn 11 10 12 (set (reg:DF 136)
(reg:DF 34 2)) "a-ticoio.adb":58 -1
 (nil))

This shows we pass in the FP arguments in integer registers (regs 3 and 4) that
we'd expect with -msoft-float, but the return values and the call pattern
itself make mention of FP regs f1 and f2 (ie, regs 33 and 34), which it
shouldn't when we've disabled hw FP.  Then LRA has no way to spill those, since
FP regs don't exist with -msoft-float, so it loops forever.

[Bug target/83387] PowerPC64: Infinite loops in do_reload() with -msoft-float

[sebastian.hu...@embedded-brains.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83387

Sebastian Huber  changed:

   What|Removed |Added

 Target|powerpc-rtems5  |powerpc64le-unknown-linux-g
   ||nu
Summary|PowerPC64 + Ada + RTEMS:|PowerPC64: Infinite loops
   |Infinite loops in   |in do_reload() with
   |do_reload() |-msoft-float

--- Comment #7 from Sebastian Huber  ---
It seems to be a general problem with -msoft-float on PowerPC64. I built a
native GCC on gcc112:

[sh@gcc2-power8 ~]$ cd /home/sh/b-gcc-git/gcc/ada/rts
[sh@gcc2-power8 rts]$ gdb --args /home/sh/b-gcc-git/gcc/gnat1 -gnatwa -quiet
-nostdinc -nostdinc -dumpbase a-coteio.ads -auxbase-strip a-coteio.o -O2
-Wextra -Wall -g -gnatpg -msoft-float -gnatO a-coteio.o a-coteio.ads -o -
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-100.el7
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later 
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "ppc64le-redhat-linux-gnu".
For bug reporting instructions, please see:
...
Warning: /home/sh/gcc-7-20161030/gcc: No such file or directory.
Warning: /home/sh/gcc-7-20161030/gcc/ada: No such file or directory.
Warning: /home/sh/gcc-7-20161030/gcc/c: No such file or directory.
Warning: /home/sh/gcc-7-20161030/gcc/cp: No such file or directory.
Warning: /home/sh/gcc-7-20161030/gcc/fortran: No such file or directory.
Warning: /home/sh/gcc-7-20161030/gcc/go: No such file or directory.
Warning: /home/sh/gcc-7-20161030/gcc/jit: No such file or directory.
Warning: /home/sh/gcc-7-20161030/gcc/lto: No such file or directory.
Warning: /home/sh/gcc-7-20161030/gcc/objc: No such file or directory.
Warning: /home/sh/gcc-7-20161030/gcc/objcp: No such file or directory.
Traceback (most recent call last):
  File "", line 1, in 
ImportError: No module named gdbhooks
/home/sh/.gdbinit:13: Error in sourced command file:
Error while executing Python code.
Reading symbols from /home/sh/b-gcc-git/gcc/gnat1...done.
(gdb) r
Starting program: /home/sh/b-gcc-git/gcc/gnat1 -gnatwa -quiet -nostdinc
-nostdinc -dumpbase a-coteio.ads -auxbase-strip a-coteio.o -O2 -Wextra -Wall -g
-gnatpg -msoft-float -gnatO a-coteio.o a-coteio.ads -o -
.file   "a-coteio.ads"
.machine power7
.abiversion 2
.section".text"
.Ltext0:
.globl __truncdfsf2
^C
Program received signal SIGINT, Interrupt.
0x108158a0 in bitmap_and_compl_into (a=0x12c7a0b0, b=)
at /home/sh/gcc-git/gcc/bitmap.c:1181
1181  gcc_checking_assert (!a->current == !a->first
Missing separate debuginfos, use: debuginfo-install glibc-2.17-196.el7.ppc64le
(gdb) bt
#0  0x108158a0 in bitmap_and_compl_into (a=0x12c7a0b0, b=) at /home/sh/gcc-git/gcc/bitmap.c:1181
#1  0x10c83208 in spill_pseudos () at /home/sh/gcc-git/gcc/bitmap.h:806
#2  lra_spill () at /home/sh/gcc-git/gcc/lra-spills.c:595
#3  0x10c56998 in lra (f=) at
/home/sh/gcc-git/gcc/lra.c:2514
#4  0x10bf216c in do_reload () at /home/sh/gcc-git/gcc/ira.c:5443
#5  (anonymous namespace)::pass_reload::execute (this=) at
/home/sh/gcc-git/gcc/ira.c:5627
#6  0x10d36f20 in execute_one_pass (pass=0x12a04650) at
/home/sh/gcc-git/gcc/passes.c:2497
#7  0x10d38114 in execute_pass_list_1 (pass=0x12a04650) at
/home/sh/gcc-git/gcc/passes.c:2586
#8  0x10d3812c in execute_pass_list_1 (pass=0x12a03570) at
/home/sh/gcc-git/gcc/passes.c:2587
#9  0x10d381b8 in execute_pass_list (fn=,
pass=) at /home/sh/gcc-git/gcc/passes.c:2597
#10 0x108cb178 in cgraph_node::expand (this=0x3fffaf68) at
/home/sh/gcc-git/gcc/context.h:48
#11 0x108ccf44 in expand_all_functions () at
/home/sh/gcc-git/gcc/cgraphunit.c:2275
#12 symbol_table::compile (this=0x3fffaf42) at
/home/sh/gcc-git/gcc/cgraphunit.c:2623
#13 0x108d084c in compile (this=0x3fffaf42) at
/home/sh/gcc-git/gcc/cgraphunit.c:2716
#14 symbol_table::finalize_compilation_unit (this=0x3fffaf42) at
/home/sh/gcc-git/gcc/cgraphunit.c:2716
#15 0x10e564b4 in compile_file () at /home/sh/gcc-git/gcc/toplev.c:480
#16 0x10277938 in do_compile () at /home/sh/gcc-git/gcc/toplev.c:2063
#17 toplev::main (this=0x3fffef50, argc=, argv=) at /home/sh/gcc-git/gcc/toplev.c:2198
#18 0x102798a8 in main (argc=, argv=0x3378) at
/home/sh/gcc-git/gcc/main.c:39