> Am 29.06.2022 um 22:44 schrieb Joseph Myers <jos...@codesourcery.com>:
>
> The LTO merging of options from different input files was broken by:
>
> commit 227a2ecf663d69972b851f51f1934d18927b62cd
> Author: Martin Liska <mli...@suse.cz>
> Date: Fri Mar 12 11:53:47 2021 +0100
>
> lto-wrapper: Use vec<cl_decoded_option> data type.
>
> Previously, find_and_merge_options would merge options it read into
> those in *opts. After this commit, options in *opts on entry to
> find_and_merge_options are ignored; the only merging that takes place
> is between multiple sets of options in the same input file that are
> read in the same call to this function (not sure how that case can
> occur at all). The effects include, for example, that if some objects
> are built with PIC enabled and others with it disabled, and the last
> LTO object processed has PIC enabled, the choice of PIC for the last
> object will result in the whole program being built as PIC, when the
> merging logic is intended to ensure that a mixture of PIC and non-PIC
> objects results in the whole program being built as non-PIC.
>
> Fix this with an extra argument to find_and_merge_options to determine
> whether merging should take place. This shows up a second issue with
> that commit (which I think wasn't actually intended to change code
> semantics at all): once merging is enabled again, the check for
> -Xassembler options became an infinite loop in the case where both
> inputs had -Xassembler options, with the same first option, so fix
> that loop to restore the previous semantics.
>
> Note that I'm not sure how LTO option merging might be tested in the
> testsuite (clearly there wasn't sufficient, if any, coverage to detect
> these bugs).
>
> Bootstrapped with no regressions for x86_64-pc-linux-gnu. OK to
> commit?
>
Ok.
Thanks,
Richard
> PR lto/106129
> * lto-wrapper.cc (find_option): Add argument start.
> (merge_and_complain): Loop over existing_opt_index and
> existing_opt2_index for Xassembler check. Update calls to
> find_option.
> (find_and_merge_options): Add argument first to determine whether
> to merge options with those passed in *opts.
> (run_gcc): Update calls to find_and_merge_options.
>
> diff --git a/gcc/lto-wrapper.cc b/gcc/lto-wrapper.cc
> index 26e06e7..795ab74 100644
> --- a/gcc/lto-wrapper.cc
> +++ b/gcc/lto-wrapper.cc
> @@ -170,13 +170,14 @@ get_options_from_collect_gcc_options (const char
> *collect_gcc,
> return decoded;
> }
>
> -/* Find option in OPTIONS based on OPT_INDEX. -1 value is returned
> - if the option is not present. */
> +/* Find option in OPTIONS based on OPT_INDEX, starting at START. -1
> + value is returned if the option is not present. */
>
> static int
> -find_option (vec<cl_decoded_option> &options, size_t opt_index)
> +find_option (vec<cl_decoded_option> &options, size_t opt_index,
> + unsigned start = 0)
> {
> - for (unsigned i = 0; i < options.length (); ++i)
> + for (unsigned i = start; i < options.length (); ++i)
> if (options[i].opt_index == opt_index)
> return i;
>
> @@ -575,13 +576,16 @@ merge_and_complain (vec<cl_decoded_option>
> &decoded_options,
> else
> j++;
>
> + int existing_opt_index, existing_opt2_index;
> if (!xassembler_options_error)
> - for (i = j = 0; ; i++, j++)
> + for (existing_opt_index = existing_opt2_index = 0; ;
> + existing_opt_index++, existing_opt2_index++)
> {
> - int existing_opt_index
> - = find_option (decoded_options, OPT_Xassembler);
> - int existing_opt2_index
> - = find_option (fdecoded_options, OPT_Xassembler);
> + existing_opt_index
> + = find_option (decoded_options, OPT_Xassembler, existing_opt_index);
> + existing_opt2_index
> + = find_option (fdecoded_options, OPT_Xassembler,
> + existing_opt2_index);
>
> cl_decoded_option *existing_opt = NULL;
> cl_decoded_option *existing_opt2 = NULL;
> @@ -1100,7 +1104,7 @@ find_crtoffloadtable (int save_temps, const char
> *dumppfx)
>
> static bool
> find_and_merge_options (int fd, off_t file_offset, const char *prefix,
> - vec<cl_decoded_option> decoded_cl_options,
> + vec<cl_decoded_option> decoded_cl_options, bool first,
> vec<cl_decoded_option> *opts, const char *collect_gcc)
> {
> off_t offset, length;
> @@ -1110,6 +1114,9 @@ find_and_merge_options (int fd, off_t file_offset,
> const char *prefix,
> int err;
> vec<cl_decoded_option> fdecoded_options;
>
> + if (!first)
> + fdecoded_options = *opts;
> +
> simple_object_read *sobj;
> sobj = simple_object_start_read (fd, file_offset, "__GNU_LTO",
> &errmsg, &err);
> @@ -1130,7 +1137,6 @@ find_and_merge_options (int fd, off_t file_offset,
> const char *prefix,
> data = (char *)xmalloc (length);
> read (fd, data, length);
> fopts = data;
> - bool first = true;
> do
> {
> vec<cl_decoded_option> f2decoded_options
> @@ -1417,8 +1423,10 @@ run_gcc (unsigned argc, char *argv[])
> int auto_parallel = 0;
> bool no_partition = false;
> const char *jobserver_error = NULL;
> + bool fdecoded_options_first = true;
> vec<cl_decoded_option> fdecoded_options;
> fdecoded_options.create (16);
> + bool offload_fdecoded_options_first = true;
> vec<cl_decoded_option> offload_fdecoded_options = vNULL;
> struct obstack argv_obstack;
> int new_head_argc;
> @@ -1510,11 +1518,13 @@ run_gcc (unsigned argc, char *argv[])
> }
>
> if (find_and_merge_options (fd, file_offset, LTO_SECTION_NAME_PREFIX,
> - decoded_options, &fdecoded_options,
> + decoded_options, fdecoded_options_first,
> + &fdecoded_options,
> collect_gcc))
> {
> have_lto = true;
> ltoobj_argv[ltoobj_argc++] = argv[i];
> + fdecoded_options_first = false;
> }
> close (fd);
> }
> @@ -1773,9 +1783,12 @@ cont1:
> fatal_error (input_location, "cannot open %s: %m", filename);
> if (!find_and_merge_options (fd, file_offset,
> OFFLOAD_SECTION_NAME_PREFIX,
> - decoded_options, &offload_fdecoded_options,
> + decoded_options,
> + offload_fdecoded_options_first,
> + &offload_fdecoded_options,
> collect_gcc))
> fatal_error (input_location, "cannot read %s: %m", filename);
> + offload_fdecoded_options_first = false;
> close (fd);
> if (filename != offload_argv[i])
> XDELETEVEC (filename);
>
> --
> Joseph S. Myers
> jos...@codesourcery.com
Re: lto: Fix option merging [PR106129]
Richard Biener via Gcc-patches Wed, 29 Jun 2022 22:31:38 -0700
- lto: Fix option merging [PR106129] Joseph Myers
- Re: lto: Fix option merging [PR106129] Richard Biener via Gcc-patches
