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Re: Something wrong with bootstrap-lto, or lto itself:
- From: Trevor Saunders <tsaunders at mozilla dot com>
- To: Richard Biener <richard dot guenther at gmail dot com>
- Cc: Toon Moene <toon at moene dot org>, gcc mailing list <gcc at gcc dot gnu dot org>
- Date: Tue, 5 Nov 2013 00:42:36 -0500
- Subject: Re: Something wrong with bootstrap-lto, or lto itself:
- Authentication-results: sourceware.org; auth=none
- References: <52715B60 dot 7060600 at moene dot org> <CAFiYyc0OorYbdQgtiPhkOmRxxPEUU-yVzWjDjJXqL68MkuRmsg at mail dot gmail dot com>
On Mon, Nov 04, 2013 at 01:29:10PM +0100, Richard Biener wrote:
> On Wed, Oct 30, 2013 at 8:17 PM, Toon Moene <toon@moene.org> wrote:
> > Consider this:
> >
> > http://gcc.gnu.org/ml/gcc-testresults/2013-10/msg02329.html
> >
> > and
> >
> > http://gcc.gnu.org/ml/gcc-testresults/2013-10/msg02258.html
> >
> > /scratch/toon/bd5894/./prev-gcc/xg++ -B/scratch/toon/bd5894/./prev-gcc/
> > -B/home/toon/compilers/install/x86_64-unknown-linux-gnu/bin/ -nostdinc++
> > -B/scratch/toon/bd5894/prev-x86_64-unknown-linux-gnu/libstdc++-v3/src/.libs
> > -B/scratch/toon/bd5894/prev-x86_64-unknown-linux-gnu/libstdc++-v3/libsupc++/.libs
> > -I/scratch/toon/bd5894/prev-x86_64-unknown-linux-gnu/libstdc++-v3/include/x86_64-unknown-linux-gnu
> > -I/scratch/toon/bd5894/prev-x86_64-unknown-linux-gnu/libstdc++-v3/include
> > -I/home/toon/compilers/gcc/libstdc++-v3/libsupc++
> > -L/scratch/toon/bd5894/prev-x86_64-unknown-linux-gnu/libstdc++-v3/src/.libs
> > -L/scratch/toon/bd5894/prev-x86_64-unknown-linux-gnu/libstdc++-v3/libsupc++/.libs
> > -g -O2 -flto=jobserver -frandom-seed=1 -DIN_GCC -fno-exceptions -fno-rtti
> > -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings
> > -Wcast-qual -Wmissing-format-attribute -pedantic -Wno-long-long
> > -Wno-variadic-macros -Wno-overlength-strings -Werror -fno-common
> > -DHAVE_CONFIG_H -static-libstdc++ -static-libgcc -o cc1plus \
> > cp/cp-lang.o c-family/stub-objc.o cp/call.o cp/decl.o
> > cp/expr.o cp/pt.o cp/typeck2.o cp/class.o cp/decl2.o cp/error.o cp/lex.o
> > cp/parser.o cp/ptree.o cp/rtti.o cp/typeck.o cp/cvt.o cp/except.o
> > cp/friend.o cp/init.o cp/method.o cp/search.o cp/semantics.o cp/tree.o
> > cp/repo.o cp/dump.o cp/optimize.o cp/mangle.o cp/cp-objcp-common.o
> > cp/name-lookup.o cp/cxx-pretty-print.o cp/cp-gimplify.o
> > cp/cp-array-notation.o cp/lambda.o cp/vtable-class-hierarchy.o attribs.o
> > incpath.o c-family/c-common.o c-family/c-cppbuiltin.o c-family/c-dump.o
> > c-family/c-format.o c-family/c-gimplify.o c-family/c-lex.o c-family/c-omp.o
> > c-family/c-opts.o c-family/c-pch.o c-family/c-ppoutput.o c-family/c-pragma.o
> > c-family/c-pretty-print.o c-family/c-semantics.o c-family/c-ada-spec.o
> > c-family/array-notation-common.o c-family/c-ubsan.o i386-c.o glibc-c.o
> > cc1plus-checksum.o libbackend.a main.o tree-browser.o libcommon-target.a
> > libcommon.a ../libcpp/libcpp.a ../libdecnumber/libdecnumber.a libcommon.a
> > ../libcpp/libcpp.a ../libbacktrace/.libs/libbacktrace.a
> > ../libiberty/libiberty.a ../libdecnumber/libdecnumber.a -lcloog-isl -lisl
> > -lmpc -lmpfr -lgmp -rdynamic -ldl -L../zlib -lz
> > In function 'release',
> > inlined from '_ZN7va_heap7reserveIbEEvRP3vecIT_S_8vl_embedEjb.part.95'
> > at /home/toon/compilers/gcc/gcc/vec.h:288:7,
> > inlined from 'reserve',
> > inlined from '_ZN3vecIb7va_heap6vl_ptrE7reserveEjb.part.96' at
> > /home/toon/compilers/gcc/gcc/vec.h:1367:3,
> > inlined from 'reserve.constprop',
> > inlined from 'reserve_exact' at
> > /home/toon/compilers/gcc/gcc/vec.h:1387:45,
> > inlined from 'safe_grow' at /home/toon/compilers/gcc/gcc/vec.h:1515:3,
> > inlined from 'safe_grow_cleared' at
> > /home/toon/compilers/gcc/gcc/vec.h:1529:3,
> > inlined from 'vect_bb_vectorization_profitable_p' at
> > /home/toon/compilers/gcc/gcc/tree-vect-slp.c:2027:0,
> > inlined from 'vect_slp_analyze_bb_1' at
> > /home/toon/compilers/gcc/gcc/tree-vect-slp.c:2174:55,
> > inlined from 'vect_slp_analyze_bb' at
> > /home/toon/compilers/gcc/gcc/tree-vect-slp.c:2229:44:
> > /home/toon/compilers/gcc/gcc/vec.h:316:3: error: attempt to free a non-heap
> > object 'life' [-Werror=free-nonheap-object]
> > ::free (v);
> > ^
> > lto1: all warnings being treated as errors
>
> Obviously fallout of the stack-vector rewrite.
>
> stack_vec<bool, 20> life;
> life.safe_grow_cleared (SLP_INSTANCE_GROUP_SIZE (instance));
>
> doesn't make much sense anyway ... why is the initial size only
> allowed as a template parameter? But then safe_grow shouldn't free
> the stack storage.
So, I'm still confused how exactly this happens, presumably we must be
trying to reserve a vector of length zero and consequently hit that code
in va_heap::reserve to free the vector if we're supposed to reserve 0
elements, but that doesn't make sense because the first check in
vec::reserve should have failed if that was the case. Unfortunately I
have no clue how to get dumps for optimization happening during lto or
otherwise debug the compiler during lto.
However I think I've convinced myself this code to have
vec_prefix::calculate_allocation return 0 if !prefix & !reserve should
never be hit, so I think we can remove it and infact that seems to get
me through atleast one round of lto.
I'll run a full lto bootstrap and standard bootstrap on x86_64-linux-gnu
with test suite, assuming those are ok is the below ok?
Trev
2013-11-4 Trevor Saunders <tsaunders@mozilla.com>
* vec.c (vec_prefix::calculate_allocation): Don't try to handle the
case of no prefix and reserving zero slots, because when that's the
case we'll never get here.
* vec.h (va_heap::reserve): Don't try and handle
vec_prefix::calculate_allocation returning zero because that should
never happen.
diff --git a/gcc/vec.c b/gcc/vec.c
index f3c3315..78252e0 100644
--- a/gcc/vec.c
+++ b/gcc/vec.c
@@ -187,9 +187,7 @@ vec_prefix::calculate_allocation (vec_prefix *pfx, unsigned reserve,
num = pfx->m_num;
}
else if (!reserve)
- /* If there's no vector, and we've not requested anything, then we
- will create a NULL vector. */
- return 0;
+ gcc_unreachable ();
/* We must have run out of room. */
gcc_assert (alloc - num < reserve);
diff --git a/gcc/vec.h b/gcc/vec.h
index f97e022..b1ebda4 100644
--- a/gcc/vec.h
+++ b/gcc/vec.h
@@ -283,11 +283,7 @@ va_heap::reserve (vec<T, va_heap, vl_embed> *&v, unsigned reserve, bool exact
{
unsigned alloc
= vec_prefix::calculate_allocation (v ? &v->m_vecpfx : 0, reserve, exact);
- if (!alloc)
- {
- release (v);
- return;
- }
+ gcc_assert (alloc);
if (GATHER_STATISTICS && v)
v->m_vecpfx.release_overhead ();
--
1.8.4.2
>
> Richard.
>
> > --
> > Toon Moene - e-mail: toon@moene.org - phone: +31 346 214290
> > Saturnushof 14, 3738 XG Maartensdijk, The Netherlands
> > At home: http://moene.org/~toon/; weather: http://moene.org/~hirlam/
> > Progress of GNU Fortran: http://gcc.gnu.org/wiki/GFortran#news