On Fri, Jul 15, 2016 at 6:46 PM, Patrick Palka <patr...@parcs.ath.cx> wrote: > The build step that invokes "ranlib libbackend.a" (which immediately > follows the invocation of "ar rc libbackend.a ...") takes over 7 seconds > on my machine and causes the entire 450MB archive to be rewritten. By > instead making the build system use ar rcs -- so that the archive and > its index are built at once -- the time it takes for the compiler to get > rebuilt gets reduced by 25%, from 27s to 20s (in a --disable-bootstrap > tree after touching a random source file). This is a pretty significant > reduction in compile time and disk io. > > Is this a good idea?
Yes and no. Do we know if all ar support rcs now? Or is it just binutils's ar? Thanks, Andrew > > Here's the patchlet I used: > > -- >8 -- > > diff --git a/Makefile.in b/Makefile.in > index 117fbf5..5ebc3a3 100644 > --- a/Makefile.in > +++ b/Makefile.in > @@ -393,7 +393,7 @@ MAKEINFOFLAGS = --split-size=5000000 > > AS = @AS@ > AR = @AR@ > -AR_FLAGS = rc > +AR_FLAGS = rcs > CC = @CC@ > CXX = @CXX@ > DLLTOOL = @DLLTOOL@ > diff --git a/Makefile.tpl b/Makefile.tpl > index 94a4f79..72ba24b 100644 > --- a/Makefile.tpl > +++ b/Makefile.tpl > @@ -396,7 +396,7 @@ MAKEINFOFLAGS = --split-size=5000000 > > AS = @AS@ > AR = @AR@ > -AR_FLAGS = rc > +AR_FLAGS = rcs > CC = @CC@ > CXX = @CXX@ > DLLTOOL = @DLLTOOL@ > diff --git a/gcc/Makefile.in b/gcc/Makefile.in > index 0786fa3..1c3a637 100644 > --- a/gcc/Makefile.in > +++ b/gcc/Makefile.in > @@ -236,7 +236,7 @@ BISONFLAGS = > FLEX = @FLEX@ > FLEXFLAGS = > AR = @AR@ > -AR_FLAGS = rc > +AR_FLAGS = rcs > NM = @NM@ > RANLIB = @RANLIB@ > RANLIB_FLAGS = @ranlib_flags@ > @@ -1883,17 +1883,14 @@ compilations: $(BACKEND) > libbackend.a: $(OBJS) > -rm -rf libbackend.a > $(AR) $(AR_FLAGS) libbackend.a $(OBJS) > - -$(RANLIB) $(RANLIB_FLAGS) libbackend.a > > libcommon-target.a: $(OBJS-libcommon-target) > -rm -rf libcommon-target.a > $(AR) $(AR_FLAGS) libcommon-target.a $(OBJS-libcommon-target) > - -$(RANLIB) $(RANLIB_FLAGS) libcommon-target.a > > libcommon.a: $(OBJS-libcommon) > -rm -rf libcommon.a > $(AR) $(AR_FLAGS) libcommon.a $(OBJS-libcommon) > - -$(RANLIB) $(RANLIB_FLAGS) libcommon.a > > # We call this executable `xgcc' rather than `gcc' > # to avoid confusion if the current directory is in the path
