Hi! On Sat, 11 Oct 2014 18:49:00 +0400, Ilya Verbin <iver...@gmail.com> wrote: > This is the last common infrastructure patch in the series.
> 1. -foffload=<targets>=<options> > By default, GCC will build offload images for all offload targets specified > in configure, with non-target-specific options passed to host compiler. > This option is used to control offload targets and options for them. > > It can be used in a few ways: > * -foffload=disable > Tells GCC to disable offload support. > OpenMP target regions will be run in host fallback mode. > * -foffload=<targets> > Tells GCC to build offload images for <targets>. > They will be built with non-target-specific options passed to host compiler. > * -foffload=<options> > Tells GCC to build offload images for all targets specified in configure. > They will be built with non-target-specific options passed to host compiler > plus <options>. > * -foffload=<targets>=<options> > Tells GCC to build offload images for <targets>. > They will be built with non-target-specific options passed to host compiler > plus <options>. > > Options specified by -foffload are appended to the end of option set, so in > case > of option conflicts they have more priority. (<https://gcc.gnu.org/PR67300>, "--foffload* undocumented", has recently been filed.) (In the following, "intelmic" is short for "x86_64-intelmicemul-linux-gnu", and "nvptx" is short for "nvptx-none".) What is the syntax to use for building both intelmic and nvptx offloading code? I understand we allow for separate -foffload=intelmic -foffload=nvptx options. Do we also intend to allow -foffload=intelmic,nvptx or -foffload=intelmic:nvptx? And then, we allow for specifying offloading compiler options with -foffload=intelmic=[...] and -foffload=nvptx=[...]; do we also intend to allow -foffload=intelmic,nvptx=[...] (do the options apply to nvptx only, or to both intelmic and nvptx?), and/or -foffload=intelmic=[...],nvptx=[...], and/or -foffload=intelmic:nvptx=[...] (which "looks a bit like" the options ought to apply to nvptx only -- or to both intelmic and nvptx?), and/or -foffload=intelmic=[...]:nvptx=[...]? Given the code in gcc/configure.ac: 939 for tgt in `echo $enable_offload_targets | sed 's/,/ /g'`; do 940 tgt=`echo $tgt | sed 's/=.*//'` 941 if test x"$offload_targets" = x; then 942 offload_targets=$tgt 943 else 944 offload_targets="$offload_targets:$tgt" 945 fi 946 done 947 AC_DEFINE_UNQUOTED(OFFLOAD_TARGETS, "$offload_targets", 948 [Define to hold the list of target names suitable for offloading.]) ..., we constuct OFFLOAD_TARGETS with the offload targets delimited by colons, but when parsing -foffload options: > --- a/gcc/gcc.c > +++ b/gcc/gcc.c > +/* Parse -foffload option argument. */ > + > +static void > +handle_foffload_option (const char *arg) > +{ > + [...] ..., we look for comma delimiters in the configure-time OFFLOAD_TARGETS: 3612 /* Check that GCC is configured to support the offload target. */ 3613 c = OFFLOAD_TARGETS; 3614 while (c) 3615 { 3616 n = strchr (c, ','); 3617 if (n == NULL) 3618 n = strchr (c, '\0'); 3619 3620 if (next - cur == n - c && strncmp (target, c, n - c) == 0) 3621 break; 3622 3623 c = *n ? n + 1 : NULL; 3624 } 3625 3626 if (!c) 3627 fatal_error (input_location, 3628 "GCC is not configured to support %s as offload target", 3629 target); So, this code will not do the right thing when configured with --enable-offload-targets=intelmic,nvptx (thus, OFFLOAD_TARGETS=intelmic:nvptx): using -foffload=nvptx will then result in "xgcc: fatal error: GCC is not configured to support nvptx as offload target". If I'm understanding the following code correctly, this supports the idea that the intention has been for -foffload=[targets]=[options] to separate the targets by commas, and separate the options by spaces -- is that correct? > --- a/gcc/lto-wrapper.c > +++ b/gcc/lto-wrapper.c > +/* Extract options for TARGET offload compiler from OPTIONS and append > + them to ARGV_OBSTACK. */ > + > +static void > +append_offload_options (obstack *argv_obstack, const char *target, > + struct cl_decoded_option *options, > + unsigned int options_count) > +{ > + [...] 571 /* Extract options for TARGET offload compiler from OPTIONS and append 572 them to ARGV_OBSTACK. */ 573 574 static void 575 append_offload_options (obstack *argv_obstack, const char *target, 576 struct cl_decoded_option *options, 577 unsigned int options_count) 578 { 579 for (unsigned i = 0; i < options_count; i++) 580 { 581 const char *cur, *next, *opts; 582 char **argv; 583 unsigned argc; 584 struct cl_decoded_option *option = &options[i]; 585 586 if (option->opt_index != OPT_foffload_) 587 continue; 588 589 /* If option argument starts with '-' then no target is specified. That 590 means offload options are specified for all targets, so we need to 591 append them. */ 592 if (option->arg[0] == '-') 593 opts = option->arg; 594 else 595 { 596 opts = strchr (option->arg, '='); 597 if (!opts) 598 continue; 599 600 cur = option->arg; 601 602 while (cur < opts) 603 { 604 next = strchr (cur, ','); 605 if (next == NULL) 606 next = opts; 607 next = (next > opts) ? opts : next; 608 609 if (strlen (target) == (size_t) (next - cur) 610 && strncmp (target, cur, next - cur) == 0) 611 break; 612 613 cur = next + 1; 614 } 615 616 if (cur >= opts) 617 continue; 618 619 opts++; 620 } 621 622 argv = buildargv (opts); 623 for (argc = 0; argv[argc]; argc++) 624 obstack_ptr_grow (argv_obstack, argv[argc]); 625 } 626 } In this case, the other use of OFFLOAD_TARGETS in gcc/gcc.c: 7570 /* Set up to remember the names of offload targets. */ 7571 7572 void 7573 driver::maybe_putenv_OFFLOAD_TARGETS () const 7574 { 7575 const char *targets = offload_targets; 7576 7577 /* If no targets specified by -foffload, use all available targets. */ 7578 if (!targets) 7579 targets = OFFLOAD_TARGETS; 7580 7581 if (strlen (targets) > 0) 7582 { 7583 obstack_grow (&collect_obstack, "OFFLOAD_TARGET_NAMES=", 7584 sizeof ("OFFLOAD_TARGET_NAMES=") - 1); 7585 obstack_grow (&collect_obstack, targets, 7586 strlen (targets) + 1); 7587 xputenv (XOBFINISH (&collect_obstack, char *)); 7588 } 7589 7590 free (offload_targets); 7591 } ... also isn't correct, because the environment variable OFFLOAD_TARGET_NAMES in contrast is meant to separate the targets with colons instead of commas (parsing code in gcc/lto-wrapper.c:parse_env_var), so we can't just set the environment variable OFFLOAD_TARGET_NAMES to OFFLOAD_TARGETS here. The following patch should address this (but I have not yet tested it): diff --git gcc/gcc.c gcc/gcc.c index 757bfc9..ad210c5a5 100644 --- gcc/gcc.c +++ gcc/gcc.c @@ -284,7 +284,8 @@ static const char *const spec_version = DEFAULT_TARGET_VERSION; static const char *spec_machine = DEFAULT_TARGET_MACHINE; static const char *spec_host_machine = DEFAULT_REAL_TARGET_MACHINE; -/* List of offload targets. */ +/* List of offload targets. Separated by colon. Empty string for + -foffload=disable. */ static char *offload_targets = NULL; @@ -4376,6 +4377,11 @@ process_command (unsigned int decoded_options_count, CL_DRIVER, &handlers, global_dc); } + /* If the user didn't specify any, default to all configured offload + targets. */ + if (offload_targets == NULL) + handle_foffload_option (OFFLOAD_TARGETS); + if (output_file && strcmp (output_file, "-") != 0 && strcmp (output_file, HOST_BIT_BUCKET) != 0) @@ -7572,22 +7578,17 @@ driver::maybe_putenv_COLLECT_LTO_WRAPPER () const void driver::maybe_putenv_OFFLOAD_TARGETS () const { - const char *targets = offload_targets; - - /* If no targets specified by -foffload, use all available targets. */ - if (!targets) - targets = OFFLOAD_TARGETS; - - if (strlen (targets) > 0) + if (offload_targets && offload_targets[0] != '\0') { obstack_grow (&collect_obstack, "OFFLOAD_TARGET_NAMES=", sizeof ("OFFLOAD_TARGET_NAMES=") - 1); - obstack_grow (&collect_obstack, targets, - strlen (targets) + 1); + obstack_grow (&collect_obstack, offload_targets, + strlen (offload_targets) + 1); xputenv (XOBFINISH (&collect_obstack, char *)); } free (offload_targets); + offload_targets = NULL; } /* Reject switches that no pass was interested in. */ Grüße, Thomas
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