Re: [PATCH] More rustspec.cc cleanups

[Philip Herron <philip.herron@embecosm.com>]

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On 06/08/2021 00:34, Mark Wielaard wrote:
> rustspec.cc was based on the Go frontend gospec.cc. Remove special
> handling of math and pthread libraries and profiling option. Handle
> .rs files instead of .go files. Keep support for linking with (static)
> librust which is currently commented out. Add generic static-librust
> option to common.opt.
> ---
>  gcc/common.opt          |   4 ++
>  gcc/rust/config-lang.in |   2 +-
>  gcc/rust/rustspec.cc    | 146 ++++++++--------------------------------
>  3 files changed, 32 insertions(+), 120 deletions(-)
>
> diff --git a/gcc/common.opt b/gcc/common.opt
> index c75dd36843e..820de1f41b0 100644
> --- a/gcc/common.opt
> +++ b/gcc/common.opt
> @@ -3449,6 +3449,10 @@ static-libgo
>  Driver
>  ; Documented for Go, but always accepted by driver.
>  
> +static-librust
> +Driver
> +; Documented for Rust, but always accepted by driver.
> +
>  static-libasan
>  Driver
>  
> diff --git a/gcc/rust/config-lang.in b/gcc/rust/config-lang.in
> index c50b72153c2..1d61d2afc6b 100644
> --- a/gcc/rust/config-lang.in
> +++ b/gcc/rust/config-lang.in
> @@ -1,4 +1,4 @@
> -# config-lang.in -- Top level configure fragment for gcc Go frontend.
> +# config-lang.in -- Top level configure fragment for gcc Rust frontend.
>  
>  # Copyright (C) 2009-2019 Free Software Foundation, Inc.
>  
> diff --git a/gcc/rust/rustspec.cc b/gcc/rust/rustspec.cc
> index 12ec874d222..806514a9d94 100644
> --- a/gcc/rust/rustspec.cc
> +++ b/gcc/rust/rustspec.cc
> @@ -1,4 +1,4 @@
> -/* rustspec.c -- Specific flags and argument handling of the gcc Go front end.
> +/* rustspec.c -- Specific flags and argument handling of the gcc Rust front end.
>     Copyright (C) 2009-2020 Free Software Foundation, Inc.
>  
>  This file is part of GCC.
> @@ -28,24 +28,10 @@ along with GCC; see the file COPYING3.  If not see
>  
>  /* This bit is set if we saw a `-xfoo' language specification.  */
>  #define LANGSPEC (1 << 1)
> -/* This bit is set if they did `-lm' or `-lmath'.  */
> -#define MATHLIB (1 << 2)
> -/* This bit is set if they did `-lpthread'.  */
> -#define THREADLIB (1 << 3)
>  /* This bit is set if they did `-lc'.  */
> -#define WITHLIBC (1 << 4)
> +#define WITHLIBC (1 << 2)
>  /* Skip this option.  */
> -#define SKIPOPT (1 << 5)
> -
> -#ifndef MATH_LIBRARY
> -#define MATH_LIBRARY "m"
> -#endif
> -#ifndef MATH_LIBRARY_PROFILE
> -#define MATH_LIBRARY_PROFILE MATH_LIBRARY
> -#endif
> -
> -#define THREAD_LIBRARY "pthread"
> -#define THREAD_LIBRARY_PROFILE THREAD_LIBRARY
> +#define SKIPOPT (1 << 3)
>  
>  void
>  lang_specific_driver (struct cl_decoded_option **in_decoded_options,
> @@ -54,38 +40,23 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>  {
>    unsigned int i, j;
>  
> -  /* If true, the user gave us the `-p' or `-pg' flag.  */
> -  bool saw_profile_flag = false;
> -
>    /* This is a tristate:
> -     -1 means we should not link in libgo
> -     0  means we should link in libgo if it is needed
> -     1  means libgo is needed and should be linked in.
> -     2  means libgo is needed and should be linked statically.  */
> +     -1 means we should not link in librust
> +     0  means we should link in librust if it is needed
> +     1  means librust is needed and should be linked in.
> +     2  means librust is needed and should be linked statically.  */
>    int library = 0;
>  
>    /* The new argument list will be contained in this.  */
>    struct cl_decoded_option *new_decoded_options;
>  
> -  /* "-lm" or "-lmath" if it appears on the command line.  */
> -  const struct cl_decoded_option *saw_math = 0;
> -
> -  /* "-lpthread" if it appears on the command line.  */
> -  const struct cl_decoded_option *saw_thread = 0;
> -
>    /* "-lc" if it appears on the command line.  */
>    const struct cl_decoded_option *saw_libc = 0;
>  
>    /* An array used to flag each argument that needs a bit set for
> -     LANGSPEC, MATHLIB, or WITHLIBC.  */
> +     LANGSPEC or WITHLIBC.  */
>    int *args;
>  
> -  /* Whether we need the thread library.  */
> -  int need_thread = 0;
> -
> -  /* By default, we throw on the math library if we have one.  */
> -  int need_math = (MATH_LIBRARY[0] != '\0');
> -
>    /* True if we saw -static.  */
>    int static_link = 0;
>  
> @@ -115,8 +86,8 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>    /* Whether the -S option was used.  */
>    bool saw_opt_S = false;
>  
> -  /* The first input file with an extension of .go.  */
> -  const char *first_go_file = NULL;
> +  /* The first input file with an extension of .rs.  */
> +  const char *first_rust_file = NULL;
>  
>    argc = *in_decoded_options_count;
>    decoded_options = *in_decoded_options;
> @@ -137,34 +108,22 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>  	  break;
>  
>  	case OPT_l:
> -	  if (strcmp (arg, MATH_LIBRARY) == 0)
> -	    {
> -	      args[i] |= MATHLIB;
> -	      need_math = 0;
> -	    }
> -	  else if (strcmp (arg, THREAD_LIBRARY) == 0)
> -	    args[i] |= THREADLIB;
> -	  else if (strcmp (arg, "c") == 0)
> +	  if (strcmp (arg, "c") == 0)
>  	    args[i] |= WITHLIBC;
>  	  else
> -	    /* Unrecognized libraries (e.g. -lfoo) may require libgo.  */
> +	    /* Unrecognized libraries (e.g. -lfoo) may require librust.  */
>  	    library = (library == 0) ? 1 : library;
>  	  break;
>  
> -	case OPT_pg:
> -	case OPT_p:
> -	  saw_profile_flag = true;
> -	  break;
> -
>  	case OPT_x:
> -	  if (library == 0 && strcmp (arg, "go") == 0)
> +	  if (library == 0 && strcmp (arg, "rust") == 0)
>  	    library = 1;
>  	  break;
>  
>  	case OPT_Xlinker:
>  	case OPT_Wl_:
>  	  /* Arguments that go directly to the linker might be .o files,
> -	     or something, and so might cause libgo to be needed.  */
> +	     or something, and so might cause librust to be needed.  */
>  	  if (library == 0)
>  	    library = 1;
>  	  break;
> @@ -197,7 +156,7 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>  	  shared_libgcc = 0;
>  	  break;
>  
> -	case OPT_static_libgo:
> +	case OPT_static_librust:
>  	  library = library >= 0 ? 2 : library;
>  	  args[i] |= SKIPOPT;
>  	  break;
> @@ -206,13 +165,13 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>  	  if (library == 0)
>  	    library = 1;
>  
> -	  if (first_go_file == NULL)
> +	  if (first_rust_file == NULL)
>  	    {
>  	      int len;
>  
>  	      len = strlen (arg);
> -	      if (len > 3 && strcmp (arg + len - 3, ".go") == 0)
> -		first_go_file = arg;
> +	      if (len > 3 && strcmp (arg + len - 3, ".rs") == 0)
> +		first_rust_file = arg;
>  	    }
>  
>  	  break;
> @@ -226,7 +185,7 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>  #endif
>  
>    /* Make sure to have room for the trailing NULL argument.  */
> -  num_args = argc + need_math + shared_libgcc + (library > 0) * 5 + 10;
> +  num_args = argc + shared_libgcc + (library > 0) * 5 + 10;
>    new_decoded_options = XNEWVEC (struct cl_decoded_option, num_args);
>  
>    i = 0;
> @@ -240,20 +199,6 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>      {
>        new_decoded_options[j] = decoded_options[i];
>  
> -      /* Make sure -lgo is before the math library, since libgo itself
> -	 uses those math routines.  */
> -      if (!saw_math && (args[i] & MATHLIB) && library > 0)
> -	{
> -	  --j;
> -	  saw_math = &decoded_options[i];
> -	}
> -
> -      if (!saw_thread && (args[i] & THREADLIB) && library > 0)
> -	{
> -	  --j;
> -	  saw_thread = &decoded_options[i];
> -	}
> -
>        if (!saw_libc && (args[i] & WITHLIBC) && library > 0)
>  	{
>  	  --j;
> @@ -268,11 +213,11 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>      }
>  
>    /* If we didn't see a -o option, add one.  This is because we need
> -     the driver to pass all .go files to go1.  Without a -o option the
> -     driver will invoke go1 separately for each input file.  FIXME:
> +     the driver to pass all .rs files to rust1.  Without a -o option the
> +     driver will invoke rust1 separately for each input file.  FIXME:
>       This should probably use some other interface to force the driver
>       to set combine_inputs.  */
> -  if (first_go_file != NULL && !saw_opt_o)
> +  if (first_rust_file != NULL && !saw_opt_o)
>      {
>        if (saw_opt_c || saw_opt_S)
>  	{
> @@ -281,7 +226,7 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>  	  int alen;
>  	  char *out;
>  
> -	  base = lbasename (first_go_file);
> +	  base = lbasename (first_rust_file);
>  	  baselen = strlen (base) - 3;
>  	  alen = baselen + 3;
>  	  out = XNEWVEC (char, alen);
> @@ -301,7 +246,7 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>        j++;
>      }
>  
> -  /* Add `-lgo' if we haven't already done so.  */
> +  /* Add `-lrust' if we haven't already done so.  */
>    if (library > 0)
>      {
>        // generate_option (OPT_l, LIBGOBEGIN, 1, CL_DRIVER,
> @@ -318,7 +263,7 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>  	}
>  #endif
>  
> -	// generate_option (OPT_l, saw_profile_flag ? LIBGO_PROFILE : LIBGO, 1,
> +	// generate_option (OPT_l, LIBGO, 1,
>  	//   	       CL_DRIVER, &new_decoded_options[j]);
>  	// added_libraries++;
>  	// j++;
> @@ -331,34 +276,6 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>  	  j++;
>  	}
>  #endif
> -
> -      /* When linking libgo statically we also need to link with the
> -	 pthread library.  */
> -      if (library > 1 || static_link)
> -	need_thread = 1;
> -    }
> -
> -  if (saw_thread)
> -    new_decoded_options[j++] = *saw_thread;
> -  else if (library > 0 && need_thread)
> -    {
> -      generate_option (OPT_l,
> -		       (saw_profile_flag ? THREAD_LIBRARY_PROFILE
> -					 : THREAD_LIBRARY),
> -		       1, CL_DRIVER, &new_decoded_options[j]);
> -      added_libraries++;
> -      j++;
> -    }
> -
> -  if (saw_math)
> -    new_decoded_options[j++] = *saw_math;
> -  else if (library > 0 && need_math)
> -    {
> -      generate_option (OPT_l,
> -		       saw_profile_flag ? MATH_LIBRARY_PROFILE : MATH_LIBRARY,
> -		       1, CL_DRIVER, &new_decoded_options[j]);
> -      added_libraries++;
> -      j++;
>      }
>  
>    if (saw_libc)
> @@ -367,15 +284,6 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>      generate_option (OPT_shared_libgcc, NULL, 1, CL_DRIVER,
>  		     &new_decoded_options[j++]);
>  
> -#if defined(TARGET_SOLARIS) && !defined(USE_GLD)
> -  /* We use a common symbol for go$zerovalue.  On Solaris, when not
> -     using the GNU linker, the Solaris linker needs an option to not
> -     warn about this.  Everything works without this option, but you
> -     get unsightly warnings at link time.  */
> -  generate_option (OPT_Wl_, "-t", 1, CL_DRIVER, &new_decoded_options[j]);
> -  j++;
> -#endif
> -
>    *in_decoded_options_count = j;
>    *in_decoded_options = new_decoded_options;
>    *in_added_libraries = added_libraries;
> @@ -383,10 +291,10 @@ lang_specific_driver (struct cl_decoded_option **in_decoded_options,
>  
>  /* Called before linking.  Returns 0 on success and -1 on failure.  */
>  int
> -lang_specific_pre_link (void) /* Not used for Go.  */
> +lang_specific_pre_link (void) /* Not used for Rust.  */
>  {
>    return 0;
>  }
>  
>  /* Number of extra output files that lang_specific_pre_link may generate.  */
> -int lang_specific_extra_outfiles = 0; /* Not used for Go.  */
> +int lang_specific_extra_outfiles = 0; /* Not used for Rust.  */

Great patch, this file has been neglected. This is now being merged
https://github.com/Rust-GCC/gccrs/pull/610

Its not 100% clear but is the compiler driver here automatically adding
in -lc or is it simply checking if it saw_libc?

Thanks

--Phil



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