[Bug tree-optimization/93401] New: [9/10 regression] It is no longer possible to use -fprofile-generate=<dir> on setups with different instrumentation and feedback directories

[hubicka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93401

            Bug ID: 93401
           Summary: [9/10 regression] It is no longer possible to use
                    -fprofile-generate=<dir> on setups with different
                    instrumentation and feedback directories
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hubicka at gcc dot gnu.org
  Target Milestone: ---

https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=42870a86829f9d6dd326d318a3a028fbceb88d94
updated coverage.c co mangle full rather than relative names into gcov dump
file names.  This solves problem with multiple files conflicting on  single
dump (PR91971) but makes it impossible to read the profile when final build
directory differs from training. This is used i.e. by Firefox and HHVM.

Mark Williams suggested -ffile-prefix-map=old=new to strip away the outer dir
of build.