Re: [PATCH] Fix unified tree breakage

[Paolo Bonzini <bonzini at gnu dot org>]

Alexandre Oliva wrote:
> On Oct  5, 2005, Paolo Bonzini <paolo.bonzini@lu.unisi.ch> wrote:
>
>
> > In 4.2, we'll have *toplevel* bootstrap enabled by default.  This is
> > what you saw indicated as "@if gcc-bootstrap", and it means that the
> > toplevel orchestrates a 3-stage build of libiberty, binutils, and
> > everything else up to gcc.  In this case it will just work because
> > stage1 will use the system assembler/linker, and stage2/3 will use the
> > previous stage of the in-tree assembler/linker:
>
>
> This is not good.  It means the libgcc build uses one pair of
> assembler/linker different from the one that gets installed.  Each
> stage must use its own assembler/linker to build the GCC libraries.

It does, I'm sorry.  It's quite complicated and sometimes I get it wrong 
myself.  :-(

The stage2 and stage3 binaries should be identical (and even the stage1 
and stage2 binaries should behave the same).  Thus, using the previous 
stage of the in-tree assembler/linker could even be correct, but it is 
not what it is done.

> I think this has to be done for all stages, and every stage must use
> its own assembler/linker pair to build any target libraries (libgcc
> included), otherwise the point of bootstrapping is sort of missed.

For toplevel bootstrap, it will be.

When I said that for 4.2 I want to remove this junk, it is because I 
would like to add a script that automatically picks the correct tool. 
For example,

run-tool --build='$$r/$(BUILD_SUBDIR)/bison/tests/bison -y' \
         --build='$$r/$(BUILD_SUBDIR)/byacc/byacc' \
         '$(CONFIGURED_YACC)

finds an in-tree bison or byacc, falling back to $(CONFIGURED_YACC).  Or,

run-tool --target='$$r/$(HOST_SUBDIR)/gas/as-new' \
         --target='$$r/$(HOST_SUBDIR)/gcc/as' \
         --host='$(AS)' \
         '$(CONFIGURED_AS_FOR_TARGET)'"

finds an in-tree target assembler, falling back to the system host 
assembler in a native configuration (target = host) or then to the 
$(CONFIGURED_AS_FOR_TARGET).  The first parameter specifies the desired 
triplet for the tool, so --host is only considered if the host and 
target triplets are identical.

This allows all the backticked `if ... ; then echo ; else echo; fi` 
expressions in Makefile.tpl to go away.

Paolo