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Re: [PATCH 6/n] OpenMP 4.0 offloading infrastructure: option handling


Hi!

On Wed, 18 Feb 2015 18:04:21 +0100, I wrote:
> On Mon, 13 Oct 2014 14:33:11 +0400, Ilya Verbin <iverbin@gmail.com> wrote:
> > On 13 Oct 12:19, Jakub Jelinek wrote:
> > > On Sat, Oct 11, 2014 at 06:49:00PM +0400, Ilya Verbin wrote:
> > > > 2. -foffload-abi=[lp64|ilp32]
> > > >    This option is supposed to tell mkoffload (and offload compiler) which ABI is
> > > > used in streamed GIMPLE.  This option is desirable, because host and offload
> > > > compilers must have the same ABI.  The option is generated by the host compiler
> > > > automatically, it should not be specified by user.
> > > 
> > > But I'd like to understand why is this one needed.
> > > Why should the compilers care?  Aggregates layout and alignment of
> > > integral/floating types must match between host and offload compilers, sure,
> > > but isn't that something streamed already in the LTO bytecode?
> > > Or is LTO streamer not streaming some types like long_type_node?
> > > I'd expect if host and offload compiler disagree on long type size that
> > > you'd just use a different integral type with the same size as long on the
> > > host.
> > > Different sized pointers are of course a bigger problem, but can't you just
> > > error out on that during reading of the LTO, or even handle it (just use
> > > some integral type for when is the pointer stored in memory, and just
> > > convert to pointer after reads from memory, and convert back before storing
> > > to memory).  Erroring out during LTO streaming in sounds just fine to me
> > > though.
> > 
> > Actually this option was developed by Bernd, so I think PTX team is going to use
> > it somehow.  In MIC's case we're planning just to check in mkoffload that host
> > and target compiler's ABI are the same.  Without this check we will crash in LTO
> > streamer with ICE, so I'd like to issue an error message, rather than crashing.
> 
> In gcc/config/i386/intelmic-mkoffload.c, this option is now parsed to
> initialize the target_ilp32 variable, which will then be used
> (target_ilp32 ? "-m32" : "-m64") when invoking different tools.
> 
> In nvptx, we've been using the following approach:
> 
> --- gcc/config/nvptx/nvptx.h
> +++ gcc/config/nvptx/nvptx.h
> @@ -54,24 +54,28 @@
>  
>  /* Type Layout.  */
>  
> +#define TARGET_64BIT \
> +  (flag_offload_abi == OFFLOAD_ABI_UNSET ? TARGET_ABI64 \
> +   : flag_offload_abi == OFFLOAD_ABI_LP64 ? true : false)
> +
>  #define DEFAULT_SIGNED_CHAR 1
>  
>  #define SHORT_TYPE_SIZE 16
>  #define INT_TYPE_SIZE 32
> -#define LONG_TYPE_SIZE (TARGET_ABI64 ? 64 : 32)
> +#define LONG_TYPE_SIZE (TARGET_64BIT ? 64 : 32)
>  #define LONG_LONG_TYPE_SIZE 64
>  #define FLOAT_TYPE_SIZE 32
>  #define DOUBLE_TYPE_SIZE 64
>  #define LONG_DOUBLE_TYPE_SIZE 64
>  
>  #undef SIZE_TYPE
> -#define SIZE_TYPE (TARGET_ABI64 ? "long unsigned int" : "unsigned int")
> +#define SIZE_TYPE (TARGET_64BIT ? "long unsigned int" : "unsigned int")
>  #undef PTRDIFF_TYPE
> -#define PTRDIFF_TYPE (TARGET_ABI64 ? "long int" : "int")
> +#define PTRDIFF_TYPE (TARGET_64BIT ? "long int" : "int")
>  
> -#define POINTER_SIZE (TARGET_ABI64 ? 64 : 32)
> +#define POINTER_SIZE (TARGET_64BIT ? 64 : 32)
>  
> -#define Pmode (TARGET_ABI64 ? DImode : SImode)
> +#define Pmode (TARGET_64BIT ? DImode : SImode)
>  
>  /* Registers.  Since ptx is a virtual target, we just define a few
>     hard registers for special purposes and leave pseudos unallocated.  */
> 
> Should we settle on one of the two, that is, either pass -m[...] from
> mkoffload, or handle flag_offload_abi in the respective backend?  I think
> I prefer the intelmic-mkoffload.c approach; this seems cleaner to me:
> mkoffload "configures" the offloading compiler.  (Also, the flag 32-bit
> vs. 64-bit flag may in fact be needed for tools other than the offloading
> compiler).

Well, "for instance", when in -m32 mode, we also need to use it in
gcc/config/nvptx/mkoffload.c:compile_native -- otherwise, later on, the
linker will not be happy with the request to link a 64-bit object file
with 32-bit object files...

> Bernd, is there any specific reason for the approach you had
> chosen?

OK to do the following instead?  (Coding style/code copied from
gcc/config/i386/intelmic-mkoffload.c for consistency.)

--- gcc/config/nvptx/mkoffload.c
+++ gcc/config/nvptx/mkoffload.c
@@ -126,6 +126,9 @@ static id_map *var_ids, **vars_tail = &var_ids;
 static const char *ptx_name;
 static const char *ptx_cfile_name;
 
+/* Shows if we should compile binaries for i386 instead of x86-64.  */
+bool target_ilp32 = false;
+
 /* Delete tempfiles.  */
 
 /* Unlink a temporary file unless requested otherwise.  */
@@ -883,6 +886,7 @@ compile_native (const char *infile, const char *outfile, const char *compiler)
   struct obstack argv_obstack;
   obstack_init (&argv_obstack);
   obstack_ptr_grow (&argv_obstack, compiler);
+  obstack_ptr_grow (&argv_obstack, target_ilp32 ? "-m32" : "-m64");
   obstack_ptr_grow (&argv_obstack, infile);
   obstack_ptr_grow (&argv_obstack, "-c");
   obstack_ptr_grow (&argv_obstack, "-o");
@@ -960,10 +964,23 @@ main (int argc, char **argv)
      passed with @file.  Expand them into argv before processing.  */
   expandargv (&argc, &argv);
 
+  /* Find out whether we should compile binaries for i386 or x86-64.  */
+  for (int i = argc - 1; i > 0; i--)
+    if (strncmp (argv[i], "-foffload-abi=", sizeof ("-foffload-abi=") - 1) == 0)
+      {
+	if (strstr (argv[i], "ilp32"))
+	  target_ilp32 = true;
+	else if (!strstr (argv[i], "lp64"))
+	  fatal_error (input_location,
+		       "unrecognizable argument of option -foffload-abi");
+	break;
+      }
+
   struct obstack argv_obstack;
   obstack_init (&argv_obstack);
   obstack_ptr_grow (&argv_obstack, driver);
   obstack_ptr_grow (&argv_obstack, "-xlto");
+  obstack_ptr_grow (&argv_obstack, target_ilp32 ? "-m32" : "-m64");
   obstack_ptr_grow (&argv_obstack, "-S");
 
   for (int ix = 1; ix != argc; ix++)
diff --git gcc/config/nvptx/nvptx.h gcc/config/nvptx/nvptx.h
index 15460b7..e74d16f 100644
--- gcc/config/nvptx/nvptx.h
+++ gcc/config/nvptx/nvptx.h
@@ -58,28 +58,24 @@
 
 /* Type Layout.  */
 
-#define TARGET_64BIT \
-  (flag_offload_abi == OFFLOAD_ABI_UNSET ? TARGET_ABI64 \
-   : flag_offload_abi == OFFLOAD_ABI_LP64 ? true : false)
-
 #define DEFAULT_SIGNED_CHAR 1
 
 #define SHORT_TYPE_SIZE 16
 #define INT_TYPE_SIZE 32
-#define LONG_TYPE_SIZE (TARGET_64BIT ? 64 : 32)
+#define LONG_TYPE_SIZE (TARGET_ABI64 ? 64 : 32)
 #define LONG_LONG_TYPE_SIZE 64
 #define FLOAT_TYPE_SIZE 32
 #define DOUBLE_TYPE_SIZE 64
 #define LONG_DOUBLE_TYPE_SIZE 64
 
 #undef SIZE_TYPE
-#define SIZE_TYPE (TARGET_64BIT ? "long unsigned int" : "unsigned int")
+#define SIZE_TYPE (TARGET_ABI64 ? "long unsigned int" : "unsigned int")
 #undef PTRDIFF_TYPE
-#define PTRDIFF_TYPE (TARGET_64BIT ? "long int" : "int")
+#define PTRDIFF_TYPE (TARGET_ABI64 ? "long int" : "int")
 
-#define POINTER_SIZE (TARGET_64BIT ? 64 : 32)
+#define POINTER_SIZE (TARGET_ABI64 ? 64 : 32)
 
-#define Pmode (TARGET_64BIT ? DImode : SImode)
+#define Pmode (TARGET_ABI64 ? DImode : SImode)
 
 /* Registers.  Since ptx is a virtual target, we just define a few
    hard registers for special purposes and leave pseudos unallocated.  */


GrÃÃe,
 Thomas

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