On Mon, Nov 24, 2014 at 01:06:45AM +0100, FX wrote:
> tl;dr: One question to build maintainers, and one patch submitted to toplevel
> configure.ac
>
> ---------------
>
> I’m looked into the issue some more, and am comparing two builds of trunk
> (exact same source), one configured with system compiler (clang) in PATH, the
> other with GCC 4.9.2 in PATH.
> At the toplevel configure, the only meaningful difference is that the
> gcc-based build sets stage1_ldflags='-static-libstdc++ -static-libgcc' while
> the clang-based has stage1_ldflags='' (clang doesn’t recognized
> -static-libstdc++).
>
> This is included into the toplevel Makefile as STAGE1_LDFLAGS (the comment
> appropriately says "Linker flags to use on the host, for stage1 or when not
> bootstrapping”).
> Those are exported by HOST_EXPORTS, which is are then used by
> configure-libcc1, all-libcc1, etc. Thus, we end up using STAGE1_LDFLAGS,
> which correspond to the system compiler, instead of the stage3 compiler (as
> we should).
>
> So, this is “false negative” part of the problem (namely, why we don’t see
> the failure when bootstrapping with clang): we use STAGE1_LDFLAGS in building
> libcc1, and with clang as system compiler we don’t use static linking of the
> C++ library. This part, I don’t know how to fix: it is for the build experts
> to address. It is a real problem: it leads to libcc1.so being linked
> dynamically to libstdc++ and libgcc, instead of statically (as it should).
>
> ---------------
>
> Second part of the question: when the freshly built g++ is used, we need to
> pass the appropriate -B options. As I understand it, the appropriate place
> for that is in the toplevel configure.ac, where we already pass down the
> respective -L options. Indeed, the attached patch restores bootstrap on
> x86_64-apple-darwin14 with gcc as system compiler (and doesn’t break the
> bootstrap with clang as system compiler).
>
> OK to commit?
Reading the toplevel Makefile and trying to understand how things work
for non-bootstrap vs. bootstrap host dirs that aren't bootstrapped,
I'd say the right fix should be something like following
(bootstrapping/regtesting it right now on x86_64-linux and i686-linux,
though it won't make much difference there, on x86_64-linux
STAGE1_LDFLAGS is equal to POSTSTAGE1_LDFLAGS and STAGE1_LIBS is equal
to POSTSTAGE1_LIBS. On i686-linux there is at least a difference
for some reason (possibly related with my setarch and gcc -m32 wrappers
hacks to make i686-linux bootstrap work on x86_64-linux box) in
*STAGE1_LDFLAGS, only the POSTSTAGE1_LDFLAGS is -static-libstdc++
-static-libgcc.
>From my reading, POSTSTAGE1_HOST_EXPORTS is clearly inappropriate for the
modules like libcc1, because it uses prev-gcc/, while we want to use gcc/,
but otherwise looking at the HOST_EXPORTS vs. POSTSTAGE1_HOST_EXPORTS
differences, LDFLAGS and HOST_LIBS is what needs changing.
For some reason POSTSTAGE1_HOST_EXPORTS sets LDFLAGS to
$(POSTSTAGE1_LDFLAGS) $(BOOT_LDFLAGS)
(the first part is ok and clear, the latter differs from the HOST_EXPORTS
$(STAGE1_LDFLAGS) $(LDFLAGS).
With my patch below, one actually ends up with
$(POSTSTAGE1_LDFLAGS) $(LDFLAGS_FOR_TARGET)
for libcc1 when bootstrapping in LDFLAGS, while previously
$(STAGE1_LDFLAGS) $(LDFLAGS_FOR_TARGET)
was used. STAGE1_L{DFLAGS,IBS} is only used in $(HOST_EXPORTS),
so at least in theory I think my patch should DTRT.
Can you please test it on Darwin (or whatever other target has similar
issues with bootstrapping libcc1)?
2014-12-05 Jakub Jelinek <ja...@redhat.com>
PR bootstrap/64023
* Makefile.tpl (EXTRA_TARGET_FLAGS): Set STAGE1_LDFLAGS
to POSTSTAGE1_LDFLAGS and STAGE1_LIBS to POSTSTAGE1_LIBS.
* Makefile.in: Regenerated.
--- Makefile.tpl.jj 2014-11-12 09:31:59.000000000 +0100
+++ Makefile.tpl 2014-12-05 17:14:16.115295667 +0100
@@ -659,6 +659,8 @@ EXTRA_TARGET_FLAGS = \
'WINDRES=$$(WINDRES_FOR_TARGET)' \
'WINDMC=$$(WINDMC_FOR_TARGET)' \
'XGCC_FLAGS_FOR_TARGET=$(XGCC_FLAGS_FOR_TARGET)' \
+ 'STAGE1_LDFLAGS=$$(POSTSTAGE1_LDFLAGS)' \
+ 'STAGE1_LIBS=$$(POSTSTAGE1_LIBS)' \
"TFLAGS=$$TFLAGS"
TARGET_FLAGS_TO_PASS = $(BASE_FLAGS_TO_PASS) $(EXTRA_TARGET_FLAGS)
--- Makefile.in.jj 2014-11-28 14:40:52.000000000 +0100
+++ Makefile.in 2014-12-05 17:15:04.322439003 +0100
@@ -853,6 +853,8 @@ EXTRA_TARGET_FLAGS = \
'WINDRES=$$(WINDRES_FOR_TARGET)' \
'WINDMC=$$(WINDMC_FOR_TARGET)' \
'XGCC_FLAGS_FOR_TARGET=$(XGCC_FLAGS_FOR_TARGET)' \
+ 'STAGE1_LDFLAGS=$$(POSTSTAGE1_LDFLAGS)' \
+ 'STAGE1_LIBS=$$(POSTSTAGE1_LIBS)' \
"TFLAGS=$$TFLAGS"
TARGET_FLAGS_TO_PASS = $(BASE_FLAGS_TO_PASS) $(EXTRA_TARGET_FLAGS)
Jakub
