Intial experiment for building dynamic images without glibc under pnacl

tests/pnacl_ld_experiments/Makefile

Index: tests/pnacl_ld_experiments/Makefile
===================================================================
--- tests/pnacl_ld_experiments/Makefile	(revision 0)
+++ tests/pnacl_ld_experiments/Makefile	(revision 0)
@@ -0,0 +1,75 @@
+
+# Copyright (c) 2012 The Native Client Authors.  All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# simple example that tries to build a mostly sandboxed shared lib
+# which is then loaded by a regular (non-sandboxed) images

[jvoung - send to chromium..., 2012/05/01 23:30:49]

Is it really "loaded by a regular (non-sandboxed) images" ?

[Robert Muth (chromium), 2012/05/02 16:18:32]

Done.

+
+ROOT=$(shell readlink -f ../../)
+TC_ROOT=$(ROOT)/toolchain/pnacl_linux_x86_64/glibc
+PNACL_CC=$(TC_ROOT)/bin/pnacl-clang
+PNACL_LD=$(TC_ROOT)/bin/pnacl-nativeld
+
+BOOTER=$(ROOT)/scons-out/opt-linux-x86-32/staging/nacl_helper_bootstrap
+LOADER=$(ROOT)/scons-out/opt-linux-x86-32/staging/sel_ldr
+LDSO=$(ROOT)/toolchain/pnacl_linux_x86_64/lib-x86-32/runnable-ld.so
+LIBPATH_SHARED=$(ROOT)/toolchain/pnacl_linux_x86_64/lib-x86-32
+PATH_CRT=$(ROOT)/toolchain/pnacl_linux_x86_64/glibc/lib
+PATH_CRT_SRC=$(ROOT)/pnacl/support
+
+COMMON_FLAGS= --pnacl-driver-verbose -save-temps
+
+RUNNER=$(BOOTER) $(LOADER) -S -E LD_DEBUG=all --r_debug=0xXXXXXXXXXXXXXXXX -a -- $(LDSO) \

[jvoung - send to chromium..., 2012/05/01 23:30:49]

80 col

[Robert Muth (chromium), 2012/05/02 16:18:32]

Done.

+        --library-path $(LIBPATH_SHARED)
+
+
+######################################################################
+
+hello1.bc:  hello1.c
+	$(PNACL_CC)  -c -I../../.. $(DEBUG_FLAGS) -o $@ $^

[jvoung - send to chromium..., 2012/05/01 23:30:49]

why that -I path? to get to "native_client/blah/blah2.h"? 

[jvoung - send to chromium..., 2012/05/01 23:30:49]

I don't think DEBUG_FLAGS is set anywhere.

[Robert Muth (chromium), 2012/05/02 16:18:32]

Done.

+
+fortytwo.bc:  fortytwo.c
+	$(PNACL_CC)  -c -I../../.. $(DEBUG_FLAGS) -o $@ $^
+
+crtbegin.bc:  $(PATH_CRT_SRC)/crtbegin.c
+	$(PNACL_CC)  -c -I../../.. $(DEBUG_FLAGS) -o $@ $^
+
+crtend.bc:  $(PATH_CRT_SRC)/crtend.c
+	$(PNACL_CC)  -c -I../../.. $(DEBUG_FLAGS) -o $@ $^
+
+#libsimple.so: fortytwo.bc
+#	$(PNACL_CC) $(LD_FLAGS) -nostdlib -shared -fPIC  -arch x86-32 -o $@ $^

[jvoung - send to chromium..., 2012/05/01 23:30:49]

Commented out stuff, but I don't think LD_FLAGS is set anywhere.  Perhaps also
set a soname for this library, and start with a .pso then go to a .so with
pnacl-translate.

[Robert Muth (chromium), 2012/05/02 16:18:32]

I'd like to explore this in the next CL

On 2012/05/01 23:30:49, jvoung wrote:

+
+LIBS = -L $(LIBPATH_SHARED)  -l:ld-2.9.so
+LD_FLAGS_NATIVE = --pnacl-allow-native -arch x86-32
+# NOTE: the duplication of crtbegin.bc.
+# The one here was build from $(PATH_CRT_SRC)/bitcode
+# The one above from $(PATH_CRT_SRC)

[jvoung - send to chromium..., 2012/05/01 23:30:49]

So, why are both crtbegins linked in?

[Robert Muth (chromium), 2012/05/02 16:18:32]

Good question. I think this is what we are currently doing
in our drivers.
Definitely something to revisit. 

On 2012/05/01 23:30:49, jvoung wrote:

[jvoung - send to chromium..., 2012/05/02 17:20:42]

Hmm, I'm pretty sure the current driver doesn't do that.  For the bitcode link:

/usr/local/google/home/nacl2/native_client/toolchain/pnacl_linux_x86_64/pkg/binutils/bin/arm-pc-nacl-ld.gold
\
    --native-client \
    --oformat \
    elf32-nacl \
//... SKIP
    toolchain/pnacl_linux_x86_64/glibc/lib/crt1.bc \
    toolchain/pnacl_linux_x86_64/glibc/lib/crti.bc \
    toolchain/pnacl_linux_x86_64/glibc/lib/crtdummy.bc \
    toolchain/pnacl_linux_x86_64/glibc/lib/crtbegin.bc \
   
scons-out/nacl-x86-32-pnacl-glibc-clang/obj/tests/browser_startup_time/hello_world.bc
\
// ... SKIP

(and there is no crtend.bc???)


However, for the native link step:


/usr/local/google/home/nacl2/native_client/toolchain/pnacl_linux_x86_64/pkg/binutils/bin/arm-pc-nacl-ld.alt
\
    --rosegment \
    --bsssegment \
    --native-client \
// SKIP ...
    toolchain/pnacl_linux_x86_64/lib-x86-32/crtbegin.o \
// ...
    toolchain/pnacl_linux_x86_64/lib-x86-32/crtend.o \
// ...


Where the .o are compiled from your PATH_CRT_SRC, but the .bc are from
PATH_CRT_SRC/bitcode.  I guess clarify that one of the crtbegins is for
exception handling (to be paired with libgcc_s), while the other is for
ctor/dtors?

+INIT = crtbegin.bc $(PATH_CRT)/crt1.bc $(PATH_CRT)/crti.bc  $(PATH_CRT)/crtdummy.bc  $(PATH_CRT)/crtbegin.bc

[jvoung - send to chromium..., 2012/05/01 23:30:49]

80 col

[robertm, 2012/05/02 17:33:12]

Done.

+
+FINI = crtend.bc

[jvoung - send to chromium..., 2012/05/01 23:30:49]

why is this crtend used instead?

[Robert Muth (chromium), 2012/05/02 16:18:32]

Just mimicking the drivers for now

+
+# we run this to steal the .o file
+# the nexe produced by this is unfortunately not a dynamic image
+# because of special handling of -l:ld-2.9.so which gets passed through as
+# --add-extra-dt-needed=ld-nacl-x86-32.so.1 which does not trigger the

[jvoung - send to chromium..., 2012/05/01 23:30:49]

What happens if you build a .pexe first instead?

[Robert Muth (chromium), 2012/05/02 16:18:32]

IIRC this did not help - I think the problem is that there
there is not other shared lib on the command line to the linker which would
"force" a dynamic image.

On 2012/05/01 23:30:49, jvoung wrote:

[jvoung - send to chromium..., 2012/05/02 17:20:42]

Would it be posssible at the native link step to set --dynamic-linker=...?  I
guess if you do that, you still need to call PNACL_LD manually to pass flags to
the linker.  With a .pso linked, it will certainly be dynamic though.

On 2012/05/02 16:18:32, Robert Muth (chromium) wrote:

[robertm, 2012/05/02 17:33:12]

the explore this together once the CL is in.

On 2012/05/02 17:20:42, jvoung wrote:

+# a dynamic image
+hello1.x86-32.nexe.dummy: hello1.bc crtend.bc crtbegin.bc
+	$(PNACL_CC) $(COMMON_FLAGS) $(LD_FLAGS_NATIVE) -nodefaultlibs  -nostdlib   $(INIT) hello1.bc $(LIBS) $(FINI)  -o $@
+
+
+# here we steal the object file from hello1.x86-32.nexe.dummy
+hello1.x86-32.nexe: hello1.x86-32.nexe.dummy
+	$(PNACL_LD) $(COMMON_FLAGS) -arch x86-32   $(LIBS) hello1.x86-32.nexe.dummy---linked.o -o $@
+
+
+######################################################################
+
+run1: hello1.x86-32.nexe
+	${RUNNER}  ./hello1.x86-32.nexe
+
+######################################################################
+
+clean:
+	rm -f *.bc *.o *.ll *.so main *.pso *.raw

[jvoung - send to chromium..., 2012/05/01 23:30:49]

clean out *.nexe too.

[Robert Muth (chromium), 2012/05/02 16:18:32]

Done.

Property changes on: tests/pnacl_ld_experiments/Makefile
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Added: svn:eol-style
   + LF