[ccache] Using ccache with -fprofile-generate/-fprofile-use
phil_adykr_endecott at chezphil.org
Wed Aug 29 17:58:29 GMT 2007
Dear ccache people,
Has anyone ever used ccache with gcc's profile-driven-optimisation? I
have tried, and hit pathname-related problems.
Profile driven optimisation is supposed to work like this: you compile
with -fprofile-generate and run your program; on termination it saves a
load of .gcda files, one for each object file. You then compile again
with -fprofile-use; it reads the .gcda files and optimises based on
their contents. I have this working with CCACHE_DISABLE set.
But when using ccache, when the instrumented program terminates it
attempts to write a series of files with names like
Presumably the code that -fprofile-generate inserted only knows the
object file name of the cache file, and tries to put its .gcda file
alongside it. Presumably when I recompile with -fprofile-use it will
fail to find these files because the new compilation will have a new
cache filename. (I only say "presumably" because it actually doesn't
get as far as that due to a permissions issue in my case.)
This looks like a pretty fundamental problem. Any ideas about how to
P.S. Please Cc: me in any replies.
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