Fix regressions in libgomp testsuite: set flag_fat_lto_objects for offload

On 17 Nov 10:57, Richard Biener wrote:
> On Fri, Nov 14, 2014 at 6:08 PM, Ilya Verbin <iverbin@gmail.com> wrote:
> > On 14 Nov 09:01, H.J. Lu wrote:
> >> On Fri, Nov 14, 2014 at 8:51 AM, Ilya Verbin <iverbin@gmail.com> wrote:
> >> > On 14 Nov 08:46, H.J. Lu wrote:
> >> >> What happens when -flto is used on command line?  Will we
> >> >> generate both LTO IR and offload IR?
> >> >
> >> > Right.
> >> >
> >> > I'm not sure whether we should make slim objects in case of LTO + offload IR...
> >> >
> >>
> >> Isn't __gnu_lto_slim only applied to regular LTO IR? Should offload IR be
> >> handled separately from regular LTO IR? It is odd to use flag_fat_lto_objects
> >> to control offload IR.
> >
> > It is handled separately, but it uses a common infrastructure with regular LTO
> > for streaming, therefore compile_file automatically emits __gnu_lto_slim when
> > there is at least one section with IR (flag_generate_lto is set).  You propose
> > to introduce a second flag like flag_fat_lto_objects to disable __gnu_lto_slim?
> 
> Err... why is offloading not guarded with a new symbol like __gnu_lto_offload?

Well, it's possible to guard offload IR with a new symbol, using a patch like
this (it is not fully regtested).  But I don't like it...  Maybe we could just
change the meaning of "__gnu_lto_v1" from "object contains LTO IR" to "object
contains any IR"?  In collect2 both LTO and offload cases are handled
identically.  Is there other place where the symbol is used?

  -- Ilya

On Mon, Nov 24, 2014 at 5:44 PM, Ilya Verbin <iverbin@gmail.com> wrote:
> On 17 Nov 10:57, Richard Biener wrote:
>> On Fri, Nov 14, 2014 at 6:08 PM, Ilya Verbin <iverbin@gmail.com> wrote:
>> > On 14 Nov 09:01, H.J. Lu wrote:
>> >> On Fri, Nov 14, 2014 at 8:51 AM, Ilya Verbin <iverbin@gmail.com> wrote:
>> >> > On 14 Nov 08:46, H.J. Lu wrote:
>> >> >> What happens when -flto is used on command line?  Will we
>> >> >> generate both LTO IR and offload IR?
>> >> >
>> >> > Right.
>> >> >
>> >> > I'm not sure whether we should make slim objects in case of LTO + offload IR...
>> >> >
>> >>
>> >> Isn't __gnu_lto_slim only applied to regular LTO IR? Should offload IR be
>> >> handled separately from regular LTO IR? It is odd to use flag_fat_lto_objects
>> >> to control offload IR.
>> >
>> > It is handled separately, but it uses a common infrastructure with regular LTO
>> > for streaming, therefore compile_file automatically emits __gnu_lto_slim when
>> > there is at least one section with IR (flag_generate_lto is set).  You propose
>> > to introduce a second flag like flag_fat_lto_objects to disable __gnu_lto_slim?
>>
>> Err... why is offloading not guarded with a new symbol like __gnu_lto_offload?
>
> Well, it's possible to guard offload IR with a new symbol, using a patch like
> this (it is not fully regtested).  But I don't like it...  Maybe we could just
> change the meaning of "__gnu_lto_v1" from "object contains LTO IR" to "object
> contains any IR"?  In collect2 both LTO and offload cases are handled
> identically.  Is there other place where the symbol is used?

I don't think so (and even collect2.c should be changed to use simple-object
to identify LTO objects rather than ar...).  But I think libtool uses
it as well.

In the patch adding flag_generate_offload sounds like a good solution,
I didn't like emitting fat LTO objects unconditionally just because we offload.

Richard.

>   -- Ilya
>
>
> diff --git a/gcc/ada/gcc-interface/decl.c b/gcc/ada/gcc-interface/decl.c
> index c133a22..f09d79d 100644
> --- a/gcc/ada/gcc-interface/decl.c
> +++ b/gcc/ada/gcc-interface/decl.c
> @@ -1490,7 +1490,8 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
>             && definition
>             && debug_info_p
>             && !optimize
> -           && !flag_generate_lto)
> +           && !flag_generate_lto
> +           && !flag_generate_offload)
>           {
>             tree param = create_param_decl (gnu_entity_name, gnu_type, false);
>             gnat_pushdecl (param, gnat_entity);
> diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c
> index 2fd99a7..fed1a3e 100644
> --- a/gcc/cgraphunit.c
> +++ b/gcc/cgraphunit.c
> @@ -2075,7 +2075,7 @@ ipa_passes (void)
>      }
>
>    /* Some targets need to handle LTO assembler output specially.  */
> -  if (flag_generate_lto)
> +  if (flag_generate_lto || flag_generate_offload)
>      targetm.asm_out.lto_start ();
>
>    if (!in_lto_p)
> @@ -2092,7 +2092,7 @@ ipa_passes (void)
>         }
>      }
>
> -  if (flag_generate_lto)
> +  if (flag_generate_lto || flag_generate_offload)
>      targetm.asm_out.lto_end ();
>
>    if (!flag_ltrans && (in_lto_p || !flag_lto || flag_fat_lto_objects))
> @@ -2176,10 +2176,10 @@ symbol_table::compile (void)
>
>    /* Offloading requires LTO infrastructure.  */
>    if (!in_lto_p && g->have_offload)
> -    flag_generate_lto = 1;
> +    flag_generate_offload = 1;
>
>    /* If LTO is enabled, initialize the streamer hooks needed by GIMPLE.  */
> -  if (flag_generate_lto)
> +  if (flag_generate_lto || flag_generate_offload)
>      lto_streamer_hooks_init ();
>
>    /* Don't run the IPA passes if there was any error or sorry messages.  */
> diff --git a/gcc/collect2.c b/gcc/collect2.c
> index 9c3a1c5..2dcebcd 100644
> --- a/gcc/collect2.c
> +++ b/gcc/collect2.c
> @@ -2392,12 +2392,16 @@ scan_prog_file (const char *prog_name, scanpass which_pass,
>            if (found_lto)
>              continue;
>
> -          /* Look for the LTO info marker symbol, and add filename to
> +          /* Look for the LTO or offload info marker symbol, and add filename to
>               the LTO objects list if found.  */
>            for (p = buf; (ch = *p) != '\0' && ch != '\n'; p++)
>              if (ch == ' '  && p[1] == '_' && p[2] == '_'
> -               && (strncmp (p + (p[3] == '_' ? 2 : 1), "__gnu_lto_v1", 12) == 0)
> -               && ISSPACE (p[p[3] == '_' ? 14 : 13]))
> +               && (((strncmp (p + (p[3] == '_' ? 2 : 1),
> +                              "__gnu_lto_v1", 12) == 0)
> +                    && ISSPACE (p[p[3] == '_' ? 14 : 13]))
> +                   || ((strncmp (p + (p[3] == '_' ? 2 : 1),
> +                                 "__gnu_offload_v1", 16) == 0)
> +                       && ISSPACE (p[p[3] == '_' ? 18 : 17]))))
>                {
>                  add_lto_object (&lto_objects, prog_name);
>
> diff --git a/gcc/common.opt b/gcc/common.opt
> index 41c8d4e..11a5500 100644
> --- a/gcc/common.opt
> +++ b/gcc/common.opt
> @@ -67,6 +67,10 @@ int *param_values
>  Variable
>  int flag_generate_lto
>
> +; Nonzero if we should write GIMPLE bytecode for offload compilation.
> +Variable
> +int flag_generate_offload
> +
>  ; True to warn about any objects definitions whose size is larger
>  ; than N bytes.  Also want about function definitions whose returned
>  ; values are larger than N bytes, where N is 'larger_than_size'.
> diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
> index 3d50ac9..3e83213 100644
> --- a/gcc/dwarf2out.c
> +++ b/gcc/dwarf2out.c
> @@ -24390,7 +24390,8 @@ dwarf2out_finish (const char *filename)
>        /* When generating LTO bytecode we can not generate new assembler
>           names at this point and all important decls got theirs via
>          free-lang-data.  */
> -      if ((!flag_generate_lto || DECL_ASSEMBLER_NAME_SET_P (decl))
> +      if (((!flag_generate_lto && !flag_generate_offload)
> +          || DECL_ASSEMBLER_NAME_SET_P (decl))
>           && DECL_ASSEMBLER_NAME (decl) != DECL_NAME (decl))
>         {
>           add_linkage_attr (node->die, decl);
> diff --git a/gcc/ipa-inline-analysis.c b/gcc/ipa-inline-analysis.c
> index 2f2993c..9d62722 100644
> --- a/gcc/ipa-inline-analysis.c
> +++ b/gcc/ipa-inline-analysis.c
> @@ -4031,7 +4031,7 @@ inline_generate_summary (void)
>
>    /* When not optimizing, do not bother to analyze.  Inlining is still done
>       because edge redirection needs to happen there.  */
> -  if (!optimize && !flag_generate_lto && !flag_wpa)
> +  if (!optimize && !flag_generate_lto && !flag_generate_offload && !flag_wpa)
>      return;
>
>    function_insertion_hook_holder =
> diff --git a/gcc/lto-streamer.c b/gcc/lto-streamer.c
> index e8347dc..af20330 100644
> --- a/gcc/lto-streamer.c
> +++ b/gcc/lto-streamer.c
> @@ -328,7 +328,7 @@ lto_streamer_init (void)
>  bool
>  gate_lto_out (void)
>  {
> -  return ((flag_generate_lto || in_lto_p)
> +  return ((flag_generate_lto || flag_generate_offload || in_lto_p)
>           /* Don't bother doing anything if the program has errors.  */
>           && !seen_error ());
>  }
> diff --git a/gcc/passes.c b/gcc/passes.c
> index a3be0bb..74b40e5 100644
> --- a/gcc/passes.c
> +++ b/gcc/passes.c
> @@ -2466,7 +2466,7 @@ ipa_write_summaries (bool offload_lto_mode)
>    struct cgraph_node *node;
>    struct cgraph_node **order;
>
> -  if (!flag_generate_lto || seen_error ())
> +  if ((!flag_generate_lto && !flag_generate_offload) || seen_error ())
>      return;
>
>    select_what_to_stream (offload_lto_mode);
> diff --git a/gcc/toplev.c b/gcc/toplev.c
> index 6e6adfa..2d84b0a 100644
> --- a/gcc/toplev.c
> +++ b/gcc/toplev.c
> @@ -672,6 +672,27 @@ compile_file (void)
>          }
>      }
>
> +  /* Emit offload marker if offload info has been previously emitted.
> +     This is used by collect2 to determine whether an object file contains IL.
> +     We used to emit an undefined reference here, but this produces
> +     link errors if an object file with IL is stored into a shared
> +     library without invoking lto1.  */
> +  if (flag_generate_offload)
> +    {
> +#if defined ASM_OUTPUT_ALIGNED_DECL_COMMON
> +      ASM_OUTPUT_ALIGNED_DECL_COMMON (asm_out_file, NULL_TREE,
> +                                     "__gnu_offload_v1",
> +                                     (unsigned HOST_WIDE_INT) 1, 8);
> +#elif defined ASM_OUTPUT_ALIGNED_COMMON
> +      ASM_OUTPUT_ALIGNED_COMMON (asm_out_file, "__gnu_offload_v1",
> +                                (unsigned HOST_WIDE_INT) 1, 8);
> +#else
> +      ASM_OUTPUT_COMMON (asm_out_file, "__gnu_offload_v1",
> +                        (unsigned HOST_WIDE_INT) 1,
> +                        (unsigned HOST_WIDE_INT) 1);
> +#endif
> +    }
> +
>    /* Attach a special .ident directive to the end of the file to identify
>       the version of GCC which compiled this code.  The format of the .ident
>       string is patterned after the ones produced by native SVR4 compilers.  */
> diff --git a/gcc/tree-inline.c b/gcc/tree-inline.c
> index d4864ae..d4ebf52 100644
> --- a/gcc/tree-inline.c
> +++ b/gcc/tree-inline.c
> @@ -4383,7 +4383,8 @@ expand_call_inline (basic_block bb, gimple stmt, copy_body_data *id)
>               || !optimize
>               || cgraph_inline_failed_type (reason) == CIF_FINAL_ERROR)
>           /* PR 20090218-1_0.c. Body can be provided by another module. */
> -         && (reason != CIF_BODY_NOT_AVAILABLE || !flag_generate_lto))
> +         && (reason != CIF_BODY_NOT_AVAILABLE
> +             || (!flag_generate_lto && !flag_generate_offload)))
>         {
>           error ("inlining failed in call to always_inline %q+F: %s", fn,
>                  cgraph_inline_failed_string (reason));
> diff --git a/gcc/tree.c b/gcc/tree.c
> index 1d5e4f6..f6a6d04 100644
> --- a/gcc/tree.c
> +++ b/gcc/tree.c
> @@ -5730,7 +5730,7 @@ free_lang_data (void)
>
>    /* If we are the LTO frontend we have freed lang-specific data already.  */
>    if (in_lto_p
> -      || !flag_generate_lto)
> +      || (!flag_generate_lto && !flag_generate_offload))
>      return 0;
>
>    /* Allocate and assign alias sets to the standard integer types