Hi, in GCC 8 we changed -fprofile-generate=<path> to use mangled absolute paths in the <path> directory. This was necessary to avoid clashes of files when gcc is executed from different directories to build different sources of same filename.
However this made it difficult to build projects on setups where instrumented build is done in one directory, feedback build in different and possibly training happens in yet another directory structure. This happens i.e. for Firefox builds for month or two. This patch adds -fprofile-prefix-path that can be used to inform gcc where the root of build directory is and strip it form the gcda filenames. This is similar to exisitng debug-prefix-map but without the map feature since it seems useless for profile data. We spent quite some time with Maritn Liska discussing options and found no better solution. I was looking how this work on LLVM and they produce single profdata file which is then transformed into kind of simple database by llvmprofdata tool. This database keys functions by filename and symbol name. If you arrane two files with same name define static variable with same symbol name this gets messedup and result in wrong info. So I think this is not very good solution and preffer the extra option. Bootstrapped/regtested x86_64-linux. I plan to commit it later today if there are no complains. I suppose our manual could have some central section on profile feedback explaining the whole setup at one place. Honza * common.opt (profile-prefix-path): New option. * coverae.c: Include diagnostics.h. (coverage_init): Strip profile prefix path. * doc/invoke.texi (-fprofile-prefix-path): Document. diff --git a/gcc/common.opt b/gcc/common.opt index bb2ea4c905d..5662d46630a 100644 --- a/gcc/common.opt +++ b/gcc/common.opt @@ -2196,6 +2196,10 @@ Enum(profile_update) String(atomic) Value(PROFILE_UPDATE_ATOMIC) EnumValue Enum(profile_update) String(prefer-atomic) Value(PROFILE_UPDATE_PREFER_ATOMIC) +fprofile-prefix-path= +Common Joined RejectNegative Var(profile_prefix_path) +remove prefix from absolute path before manging name for -fprofile-generate= and -fprofile-use=. + fprofile-generate Common Enable common options for generating profile info for profile feedback directed optimizations. diff --git a/gcc/coverage.c b/gcc/coverage.c index 30ae84df90f..d09a5749fbd 100644 --- a/gcc/coverage.c +++ b/gcc/coverage.c @@ -49,6 +49,7 @@ along with GCC; see the file COPYING3. If not see #include "intl.h" #include "auto-profile.h" #include "profile.h" +#include "diagnostic.h" #include "gcov-io.c" @@ -1221,6 +1222,19 @@ coverage_init (const char *filename) const char *separator = "/"; #endif filename = concat (getpwd (), separator, filename, NULL); + if (profile_prefix_path) + { + if (!strncmp (filename, profile_prefix_path, + strlen (profile_prefix_path))) + { + filename += strlen (profile_prefix_path); + while (*filename == *separator) + filename++; + } + else + warning (0, "filename %s does not start with profile prefix %s", + filename, profile_prefix_path); + } filename = mangle_path (filename); len = strlen (filename); } diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index be7b5bb7d71..afd8a6dbc03 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -549,8 +549,9 @@ Objective-C and Objective-C++ Dialects}. @gccoptlist{-p -pg -fprofile-arcs --coverage -ftest-coverage @gol -fprofile-abs-path @gol -fprofile-dir=@var{path} -fprofile-generate -fprofile-generate=@var{path} @gol --fprofile-note=@var{path} -fprofile-update=@var{method} @gol --fprofile-filter-files=@var{regex} -fprofile-exclude-files=@var{regex} -fprofile-reproducibility @gol +-fprofile-note=@var{path} -fprofile-prefix-path=@var{path} @gol +-fprofile-update=@var{method} -fprofile-filter-files=@var{regex} @gol +-fprofile-exclude-files=@var{regex} -fprofile-reproducibility @gol -fsanitize=@var{style} -fsanitize-recover -fsanitize-recover=@var{style} @gol -fasan-shadow-offset=@var{number} -fsanitize-sections=@var{s1},@var{s2},... @gol -fsanitize-undefined-trap-on-error -fbounds-check @gol @@ -13398,6 +13399,20 @@ If @var{path} is specified, GCC saves @file{.gcno} file into @var{path} location. If you combine the option with multiple source files, the @file{.gcno} file will be overwritten. +@item -fprofile-prefix-path=@var{path} + +This option can be used in combination with +@option{profile-generate=}@var{profile_dir} and +@option{profile-use=}@var{profile_dir} to inform GCC where is the base +directory of built source tree. By default @var{profile_dir} will contain +files with mangled absolute paths of all object files in the built project. +This is not desirable when directory used to build the instrumented binary +differs from the directory used to build the binary optimized with profile +feedback because the profile data will not be found during the optimized build. +In such setups @option{-fprofile-prefix-path=}@var{path} with @var{path} +pointing to the base directory of the build can be used to strip the irrelevant +part of the path and keep all file names relative to the main build directory. + @item -fprofile-update=@var{method} @opindex fprofile-update