Re: [gomp4] Add -foffload-abi support for PPC

[Thomas Schwinge <thomas at codesourcery dot com>]

Hi!

rs6000/powerpc port maintainer copied.

On Tue, 6 Oct 2015 11:38:04 -0500, James Norris <jnorris@codesourcery.com> wrote:
> The attached patch adds the -foffload-abi option support for PPC.
> Only support for the 64-bit ABI has been added.

(Yes, only powerpc64le-linux-gnu configurations can be supported.)

> Committed after regtesting with x86_64 and powerpc64le.

Such a patch needs to go into trunk.  (It's of course OK to test-drive it
on gomp-4_0-branch first.)

However:

> +	* common.opt (OFFLOAD_ABI_PPC64): New enum.
> +	* config/nvptx/mkoffload.c (compile_native): Handle new enum.
> +	(main): Handle new option.
> +	* config/rs6000/rs6000.c (rs6000_offload_options): New hook.
> +	* gcc/coretypes.h (OFFLOAD_ABI_PPC64): New enum.

> --- a/gcc/common.opt
> +++ b/gcc/common.opt
> @@ -1730,6 +1730,9 @@ Enum(offload_abi) String(ilp32) Value(OFFLOAD_ABI_ILP32)
>  EnumValue
>  Enum(offload_abi) String(lp64) Value(OFFLOAD_ABI_LP64)
>  
> +EnumValue
> +Enum(offload_abi) String(ppc64) Value(OFFLOAD_ABI_PPC64)

> --- a/gcc/config/nvptx/mkoffload.c
> +++ b/gcc/config/nvptx/mkoffload.c
> @@ -367,6 +367,8 @@ compile_native (const char *infile, const char *outfile, const char *compiler)
>      case OFFLOAD_ABI_ILP32:
>        obstack_ptr_grow (&argv_obstack, "-m32");
>        break;
> +    case OFFLOAD_ABI_PPC64:
> +      break;
>      default:
>        gcc_unreachable ();
>      }
> @@ -458,6 +460,8 @@ main (int argc, char **argv)
>  	    offload_abi = OFFLOAD_ABI_LP64;
>  	  else if (strcmp (argv[i] + strlen (STR), "ilp32") == 0)
>  	    offload_abi = OFFLOAD_ABI_ILP32;
> +	  else if (strcmp (argv[i] + strlen (STR), "ppc64") == 0)
> +	    offload_abi = OFFLOAD_ABI_PPC64;
>  	  else
>  	    fatal_error (input_location,
>  			 "unrecognizable argument of option " STR);
> @@ -485,6 +489,8 @@ main (int argc, char **argv)
>      case OFFLOAD_ABI_ILP32:
>        obstack_ptr_grow (&argv_obstack, "-m32");
>        break;
> +    case OFFLOAD_ABI_PPC64:
> +      break;
>      default:
>        gcc_unreachable ();
>      }
> @@ -518,7 +524,8 @@ main (int argc, char **argv)
>  
>    /* PR libgomp/65099: Currently, we only support offloading in 64-bit
>       configurations, and only for OpenACC offloading.  */
> -  if (offload_abi == OFFLOAD_ABI_LP64 && fopenacc)
> +  if ((offload_abi == OFFLOAD_ABI_LP64
> +      || (offload_abi == OFFLOAD_ABI_PPC64)) && fopenacc)
>      {
>        ptx_name = make_temp_file (".mkoffload");
>        obstack_ptr_grow (&argv_obstack, "-o");

> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c

> +#undef TARGET_OFFLOAD_OPTIONS
> +#define TARGET_OFFLOAD_OPTIONS rs6000_offload_options

> +/* Implement the TARGET_OFFLOAD_OPTIONS hook.  */
> +static char *
> +rs6000_offload_options (void)
> +{
> +  return xstrdup ("-foffload-abi=ppc64");
> +}

> --- a/gcc/coretypes.h
> +++ b/gcc/coretypes.h
> @@ -170,7 +170,8 @@ enum tls_model {
>  enum offload_abi {
>    OFFLOAD_ABI_UNSET,
>    OFFLOAD_ABI_LP64,
> -  OFFLOAD_ABI_ILP32
> +  OFFLOAD_ABI_ILP32,
> +  OFFLOAD_ABI_PPC64
>  };

No, that's not how I meant it to be done; I wrote:

| On Mon, 5 Oct 2015 07:06:55 -0500, James Norris <James_Norris@mentor.com> wrote:
| > [The -foffload-abi parameter] is not passed [to mkoffload] when using the
| > ppc compiler, and as a result the 'unreachable' assertion [in mkoffload]
| > went off.
| 
| That's the bug: you need to pass this parameter: the target (a.k.a. host)
| and offload target (a.k.a. device) compilers need to agree on the ABI to
| use.  This should be straightforward to do; see here:
| 
|     $ git grep -i offload.options -- gcc/config/i386/
|     gcc/config/i386/i386.c:/* Implement the TARGET_OFFLOAD_OPTIONS hook.  */
|     gcc/config/i386/i386.c:ix86_offload_options (void)
|     gcc/config/i386/i386.c:#undef TARGET_OFFLOAD_OPTIONS
|     gcc/config/i386/i386.c:#define TARGET_OFFLOAD_OPTIONS \
|     gcc/config/i386/i386.c:  ix86_offload_options
| 
| gcc/config/i386/i386.c:ix86_offload_options:
| 
|     /* Implement the TARGET_OFFLOAD_OPTIONS hook.  */
|     static char *
|     ix86_offload_options (void)
|     {
|       if (TARGET_LP64)
|         return xstrdup ("-foffload-abi=lp64");
|       return xstrdup ("-foffload-abi=ilp32");
|     }
| 
| In case that PowerPC supports additional ABIs, you need to add these to
| gcc/coretypes.h:enum offload_abi, and adjust the parsing in the
| mkoffloads (I can easily test the IntelMIC mkoffload patch for you); of
| course we don't need to support anything but the 64-bit ABI (that you're
| currently already using, I suppose).

From a quick look at the *_TYPE_SIZE definitions in
gcc/config/rs6000/rs6000.h as well as
<http://refspecs.linuxfoundation.org/elf/elfspec_ppc.pdf>, "3-1
Fundamental Types", and
<http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.html#FUND-TYPE>,
I gather we're dealing with regular ilp32/lp64 here.  Then, I assume the
right thing is to use the 64BIT flag from gcc/config/rs6000/sysv4.opt
(which, per gcc/config.gcc I suppose is used for the relevant
powerpc64le-linux-gnu configuration).  (David?)

I'm not sure where to place the TARGET_OFFLOAD_OPTIONS #define and the
function definition in rs6000.c.  (David?)

So, please revert your patch and instead try the following.

--- gcc/config/rs6000/rs6000.c
+++ gcc/config/rs6000/rs6000.c
@@ -1688,6 +1688,9 @@ static const struct attribute_spec rs6000_attribute_table[] =
 #define TARGET_LIBGCC_SHIFT_COUNT_MODE rs6000_abi_word_mode
 #undef TARGET_UNWIND_WORD_MODE
 #define TARGET_UNWIND_WORD_MODE rs6000_abi_word_mode
+
+#undef TARGET_OFFLOAD_OPTIONS
+#define TARGET_OFFLOAD_OPTIONS rs6000_offload_options
 
 
 /* Processor table.  */
@@ -9532,6 +9535,16 @@ rs6000_abi_word_mode (void)
   return TARGET_32BIT ? SImode : DImode;
 }
 
+/* Implement the TARGET_OFFLOAD_OPTIONS hook.  */
+static char *
+rs6000_offload_options (void)
+{
+  if (TARGET_64BIT)
+    return xstrdup ("-foffload-abi=lp64");
+  else
+    return xstrdup ("-foffload-abi=ilp32");
+}
+
 /* On rs6000, function arguments are promoted, as are function return
    values.  */
 


GrÃÃe,
 Thomas

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