Bug #11979: gcc-6 fails to optimize regcomp.c:compile_length_quantifier_node()

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: 2.2.4, 2.3.0
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN

[t-nissie (Takeshi Nishimatsu)]

This may be a GCC version specific issue.
gcc-6, an experimental snapshot from http://ftp.tsukuba.wide.ad.jp/software/gcc/snapshots/6-20160110/ ,
fails to compile ruby-2.2.4 and ruby-2.3.0 with an error of
template/encdb.h.tmpl:63:in `block (4 levels) in ': x_emoji.h:8: ENC_REPLICATE: UTF-8 is not defined yet. (replica UTF8-DoCoMo) (ArgumentError) .
I confirmed it both on Linux and Mac OS X.

gcc-4.9.2 could compile ruby-2.3.0.
/usr/bin/gcc of Mac OS X (Apple LLVM version 7.0.2 (clang-700.1.81)) could compile ruby-2.3.0, too.

Maybe, I should report it to https://gcc.gnu.org/bugzilla/ .
Could you tell me how to make small reproducible code?
(Or, please report it to the bugzilla with small code ;-)

Compile log:

$ uname -a
Linux emerald01 2.6.32-573.12.1.el6.x86_64 #1 SMP Tue Dec 15 21:19:08 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
$ tar xf ruby-2.3.0.tar.xz
$ mkdir ruby-2.3.0/Linux-x86_64-gcc-6-20160110-emerald01
$ cd    ruby-2.3.0/Linux-x86_64-gcc-6-20160110-emerald01
$ pwd
$ ../configure
$ make -j16
$ make
$ make V=1
	CC = gcc
	LD = ld
	LDSHARED = gcc -shared
	CFLAGS = -O3 -fno-fast-math -ggdb3 -Wall -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wunused-variable -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wimplicit-function-declaration -Wdeprecated-declarations -Wno-packed-bitfield-compat -std=iso9899:1999
	XCFLAGS = -D_FORTIFY_SOURCE=2 -fstack-protector -fno-strict-overflow -fvisibility=hidden -DRUBY_EXPORT -fPIE
	CPPFLAGS =   -I. -I.ext/include/x86_64-linux -I../include -I..
	DLDFLAGS = -fstack-protector -pie
	SOLIBS = -lgmp
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../configure --enable-languages=c,c++,fortran,go,objc --with-gmp-include=/usr/local/include --with-gmp-lib=/usr/local/lib64 --with-mpfr-include=/usr/local/include --with-mpfr-lib=/usr/local/lib64 --with-mpc-include=/usr/local/include --with-mpc-lib=/usr/local/lib64
Thread model: posix
gcc version 6.0.0 20160110 (experimental) (GCC)
./miniruby -I../lib -I. -I.ext/common  ../enc/make_encmake.rb --builtin-encs="enc/ascii.o enc/us_ascii.o enc/unicode.o enc/utf_8.o" --builtin-transes="enc/trans/newline.o" --module  enc.mk
./miniruby -I../lib -I. -I.ext/common  ../tool/generic_erb.rb -c -o encdb.h ../template/encdb.h.tmpl ../enc enc
../template/encdb.h.tmpl:63:in `block (4 levels) in <main>': x_emoji.h:8: ENC_REPLICATE: UTF-8 is not defined yet. (replica UTF8-DoCoMo) (ArgumentError)
	from ../template/encdb.h.tmpl:43:in `each_line'
	from ../template/encdb.h.tmpl:43:in `block (3 levels) in <main>'
	from ../template/encdb.h.tmpl:41:in `open'
	from ../template/encdb.h.tmpl:41:in `block (2 levels) in <main>'
	from ../template/encdb.h.tmpl:38:in `each'
	from ../template/encdb.h.tmpl:38:in `block in <main>'
	from ../template/encdb.h.tmpl:34:in `each'
	from ../template/encdb.h.tmpl:34:in `<main>'
	from /home002/t-nissie/COMMON/work/ruby/ruby/ruby-2.3.0/lib/erb.rb:864:in `eval'
	from /home002/t-nissie/COMMON/work/ruby/ruby/ruby-2.3.0/lib/erb.rb:864:in `result'
	from ../tool/generic_erb.rb:38:in `<main>'
make: *** [encdb.h] Error 1

[t-nissie (Takeshi Nishimatsu)]

This IS a GCC version specific issue.

make -j16 optflags="-O0 -fno-fast-math"

can compile ruby-2.3.0, but

make -j16 optflags="-O1 -fno-fast-math"

cannot.

I want to know which file in ruby-2.3.0 reveals this issue of GCC-6.

[t-nissie (Takeshi Nishimatsu)]

• Subject changed from with gcc-6, template/encdb.h.tmpl:63:in `block (4 levels) in <main>': x_emoji.h:8: ENC_REPLICATE: UTF-8 is not defined yet. (replica UTF8-DoCoMo) (ArgumentError) to gcc-6 fails to optimize regcomp.c

gcc-6 fails to optimize regcomp.c.

$ ../configure CC=/usr/local/bin/gcc
$ make -j4 encdb.h   # => ArgumentError
$ rm regcomp.o
$ make optflags="-O0 -fno-fast-math" V=1 encdb.h
    :
gcc version 6.0.0 20151115 (experimental) (GCC)
    :
encdb.h updated
$ make -j4
$ make check
    :
# Running tests:

Finished tests in 451.167437s, 34.9227 tests/s, 4957.5298 assertions/s.
15756 tests, 2236676 assertions, 0 failures, 0 errors, 53 skips

ruby -v: ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-darwin15]
check succeeded
$

I want to know where I should put #pragma optimization_level 0 .

[t-nissie (Takeshi Nishimatsu)]

• Subject changed from gcc-6 fails to optimize regcomp.c to gcc-6 fails to optimize regcomp.c:compile_length_quantifier_node()

gcc-6 fails to optimize ruby-2.3.0/regcomp.c:compile_length_quantifier_node()
and cannot build the ruby. Even the -O1 optimization option fails.
Adding __attribute__((optimize("O0"))) before the function can evade this issue.
I confirmed this issue both on GNU/Linux and Mac OS X.

Please note that there are two compile_length_quantifier_node() in ruby-2.3.0/regcomp.c.
gcc-6 fails to optimize second one at the line 985.

gcc-4.9.2 could build ruby-2.3.0.
/usr/bin/gcc of Mac OS X (Apple LLVM version 7.0.2 (clang-700.1.81)) could
build ruby-2.3.0, too.

I will report this issue to https://gcc.gnu.org/bugzilla/ tomorrow.

$ wget https://cache.ruby-lang.org/pub/ruby/2.3/ruby-2.3.0.tar.xz
$ shasum ruby-2.3.0.tar.xz | grep 96e620e38af351c8da63e40cfe217ec79f912ba1
$ tar xf ruby-2.3.0.tar.xz
$ mkdir  ruby-2.3.0/build_on_MacOSX
$ cd     ruby-2.3.0/build_on_MacOSX
$ /usr/local/bin/gcc --version
gcc (GCC) 6.0.0 20151115 (experimental)
$ ../configure CC=/usr/local/bin/gcc
$ make -j4
    :
generating encdb.h
../template/encdb.h.tmpl:63:in `block (4 levels) in <main>': x_emoji.h:8: ENC_REPLICATE: UTF-8 is not defined yet. (replica UTF8-DoCoMo) (ArgumentError)
    :
$ sed -e '984 a\
> __attribute__((optimize("O0")))' ../regcomp.c > regcomp.c
$ diff -u ../regcomp.c .
--- ../regcomp.c        2015-12-09 16:30:44.000000000 +0900
+++ ./regcomp.c 2016-01-14 08:21:52.798816125 +0900
@@ -982,6 +982,7 @@
 #else /* USE_COMBINATION_EXPLOSION_CHECK */
 static int
+__attribute__((optimize("O0")))
 compile_length_quantifier_node(QtfrNode* qn, regex_t* reg)
 {
   int len, mod_tlen;
$ make V=1 encdb.h
    :
./miniruby -I../lib -I. -I.ext/common  ../tool/generic_erb.rb -c -o encdb.h ../template/encdb.h.tmpl ../enc enc
encdb.h updated
$ make -j4
$ make check
    :
# Running tests:

Finished tests in 453.556568s, 34.7388 tests/s, 4931.0101 assertions/s.
15756 tests, 2236492 assertions, 0 failures, 0 errors, 53 skips

ruby -v: ruby 2.3.0p0 (2015-12-25 revision 53290) [x86_64-darwin15]
check succeeded
$

[t-nissie (Takeshi Nishimatsu)]

I reported this issue as https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69291 with new info of:

I found strange behavior. If I built the ruby in /tmp on CentOS 6.7,
this issue does not stop to make encdb.h. But anyway, it stops to make rdoc
with Segmentation fault. Adding attribute((optimize("O0"))) can eliminate
the Segmentation fault, too.

Currently I got one comment:

Markus Trippelsdorf 2016-01-15 05:50:50 UTC
I think this bug is invalid, because ruby invokes undefined behavior, see:
https://bugs.ruby-lang.org/issues/11831

[t-nissie (Takeshi Nishimatsu)]

Sorry, but GCC developers judged my bug report as INVALID.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69291

On the other hand, the same build error is reported in Ubuntu:
amd64 build of ruby2.2 2.2.3-2 in ubuntu xenial RELEASE
https://launchpad.net/ubuntu/+archive/test-rebuild-20151218.1-gcc6/+build/8718227

[naruse (Yui NARUSE)]

• Related to Bug #11831: Undefined behavior issues added

Takeshi Nishimatsu wrote:

Sorry, but GCC developers judged my bug report as INVALID.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69291

On the other hand, the same build error is reported in Ubuntu:
amd64 build of ruby2.2 2.2.3-2 in ubuntu xenial RELEASE
https://launchpad.net/ubuntu/+archive/test-rebuild-20151218.1-gcc6/+build/8718227

I changed the resolution to "fixed". Today's gcc trunk compiles ruby without any issues.

[naruse (Yui NARUSE)]

• Status changed from Open to Closed

octoploid octoploid wrote:

Takeshi Nishimatsu wrote:

Sorry, but GCC developers judged my bug report as INVALID.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69291

On the other hand, the same build error is reported in Ubuntu:
amd64 build of ruby2.2 2.2.3-2 in ubuntu xenial RELEASE
https://launchpad.net/ubuntu/+archive/test-rebuild-20151218.1-gcc6/+build/8718227

I changed the resolution to "fixed". Today's gcc trunk compiles ruby without any issues.

Thank you for notice that, I close this.

[t-nissie (Takeshi Nishimatsu)]

FYI, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69291 was REOPENED,
because the "Issue still happens on i586 and fails the ruby build".