Ok. I should have tried it before hand. ccache *doesnt't* notice the addition of the new header and still gives me a .o file from the first invocation.
bug? On 18 October 2013 10:54, Ian Norton <inor...@gmail.com> wrote: > Hello All, > > I have a question about direct mode, it follows on from an old thread > I've seen in the archives: > > http://www.mail-archive.com/ccache@lists.samba.org/msg00150.html > > I'll quote inline and follow on. > > Joel Rosdahl wrote: >> tridge wrote: >> > Also, does the hashtable used for included_files preserve the >> > ordering? (the order of includes is also vital). Or do you rely on the >> > hash of the file that does the #include changing for that? > >> The hashtable is unordered, and yes, I rely on the hash of the input >> file to keep track of the ordering, and also of course on the include >> file hashes. For a given manifest, the source file (and therefore the >> order of the first level of include files) is known since the manifest >> is looked up given the hash of the input file (and some more >> information), and all other levels of include files are taken >> care of using the same kind of reasoning. In other words, if the >> include file order changes in some file, then the hash of that file >> changes too, which leads to a cache miss. Which include files the >> preprocessor reads is of course also a function of compiler options >> like -I, but that is handled by also hashing those options when >> computing the hash in direct mode. Do you see any potential problem >> here? > > I realise I'm probably missing something, but how does direct mode > handle the case where > the command line args have not changed, and nor have the source file > or previously used headers *but* a header file has been added to a > folder on one of the -I paths? eg: > > hello.c: > #include "test.h" > > inc1/test.h: > void hello(void); > > gcc -I inc2 -I inc1 -c hello.c > > later, someone makes a new file: > > inc2/test.h: > int hello(void); > > The same command line and original inputs would result in a different file. > > How does direct mode cover this case ( all our common input data has > not changed ) > > Many Thanks, ccache is fantastic btw! > > Ian _______________________________________________ ccache mailing list ccache@lists.samba.org https://lists.samba.org/mailman/listinfo/ccache
