[Bug c/58928] New: Different results from gcc when -mlzcnt is used

2013-10-30 Thread mikeb01 at gmail dot com 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58928

Bug ID: 58928
   Summary: Different results from gcc when -mlzcnt is used
   Product: gcc
   Version: 4.8.2
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c
  Assignee: unassigned at gcc dot gnu.org
  Reporter: mikeb01 at gmail dot com

Created attachment 31113
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31113&action=edit
Preprossed test.c code

I have the following code:

#include 
#include 
#include 

long long lzcnt(long long l)
{
return __lzcnt64(l);
}

int main(int argc, char** argv)
{
printf("%lld\n", lzcnt(atoll(argv[1])));
return 0;
}

If I compile and run with and without the -mlzcnt flag I get different results:

$ gcc src/test.c -D__LZCNT__ -mlzcnt && ./a.out 2047
10

$ gcc src/test.c -D__LZCNT__ && ./a.out 2047
53

$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.8.2/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla
--enable-bootstrap --enable-shared --enable-threads=posix
--enable-checking=release --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-gnu-unique-object
--enable-linker-build-id --with-linker-hash-style=gnu
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada,go,lto --enable-plugin
--enable-initfini-array --enable-java-awt=gtk --disable-dssi
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre
--enable-libgcj-multifile --enable-java-maintainer-mode
--with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib
--with-isl=/builddir/build/BUILD/gcc-4.8.2-20131017/obj-x86_64-redhat-linux/isl-install
--with-cloog=/builddir/build/BUILD/gcc-4.8.2-20131017/obj-x86_64-redhat-linux/cloog-install
--with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.8.2 20131017 (Red Hat 4.8.2-1) (GCC) 

File test.i attached.  It was the same for both compilations, so only one file
attached.

[Bug target/58928] Different results from gcc when -mlzcnt is used

2014-01-16 Thread mikeb01 at gmail dot com 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58928

--- Comment #2 from Michael Barker  ---
> Hope helps

What hardware platform are you testing on?  I'm running on Ivy Bridge:

Intel(R) Xeon(R) CPU E5620 @2.40GHz

Could you put the assembler that you see on the ticket:

With -mlzcnt:

00400580 :
  400580:55   push   %rbp
  400581:48 89 e5 mov%rsp,%rbp
  400584:48 89 7d e8  mov%rdi,-0x18(%rbp)
  400588:48 8b 45 e8  mov-0x18(%rbp),%rax
  40058c:48 89 45 f8  mov%rax,-0x8(%rbp)
  400590:f3 48 0f bd 45 f8lzcnt  -0x8(%rbp),%rax
  400596:48 98cltq   
  400598:5d   pop%rbp
  400599:c3   retq   

Without -mlzcnt:

00400580 :
  400580:55   push   %rbp
  400581:48 89 e5 mov%rsp,%rbp
  400584:48 89 7d e8  mov%rdi,-0x18(%rbp)
  400588:48 8b 45 e8  mov-0x18(%rbp),%rax
  40058c:48 89 45 f8  mov%rax,-0x8(%rbp)
  400590:48 0f bd 45 f8   bsr-0x8(%rbp),%rax
  400595:48 83 f0 3f  xor$0x3f,%rax
  400599:48 98cltq   
  40059b:5d   pop%rbp
  40059c:c3   retq

[Bug target/58928] Different results from gcc when -mlzcnt is used

2014-01-18 Thread mikeb01 at gmail dot com 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58928

--- Comment #5 from Michael Barker  ---
(In reply to Jakub Jelinek from comment #4)
> Intel(R) Xeon(R) CPU E5620 @2.40GHz
> is not IvyBridge, plus even IvyBridge doesn't support lzcnt insn, only
> Haswell or some recent AMD CPUs.  So, this looks like user error, you
> shouldn't compile code you intend to run on non-lzcnt CPUs with -mlzcnt.

Sorry, shelled into the wrong machine when running the command.  Actual model
number is (i7-3770).  Happy with the explanation, please close.

There is a further issue that the bug.c code won't compile under g++, due to a
missing builtin.

/.../lzcntintrin.h:38:29: error: ‘__builtin_clzs’ was not declared in this
scope
   return __builtin_clzs (__X);

However I will raise a separate bug for that.

[Bug c++/59874] New: Missing builtin (__builtin_clzs) when compiling with g++

2014-01-18 Thread mikeb01 at gmail dot com 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59874

Bug ID: 59874
   Summary: Missing builtin (__builtin_clzs) when compiling with
g++
   Product: gcc
   Version: 4.8.2
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: mikeb01 at gmail dot com

Created attachment 31888
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31888&action=edit
Preprocessed version of bug.cc

The following code:

#include 

int main(int argc, char** argv)
{
return __lzcnt32(2047);
}

Fails to compile using g++ (works fine with gcc).  It will compile if the
-mlzcnt switch is used, but on some platforms that will generate incorrect
code.

The __builtin_clzs does not appear to be defined when using the c++ compiler. 
If I hand modify the lzcntintrin.h file and comment out the whole definition of
the __lzcnt16 intrinsic it works okay and generates the expected code.

$ g++ -v -save-temps -D__LZCNT__ bug.cc
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.8.2/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla
--enable-bootstrap --enable-shared --enable-threads=posix
--enable-checking=release --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-gnu-unique-object
--enable-linker-build-id --with-linker-hash-style=gnu
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada,go,lto --enable-plugin
--enable-initfini-array --enable-java-awt=gtk --disable-dssi
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre
--enable-libgcj-multifile --enable-java-maintainer-mode
--with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib
--with-isl=/builddir/build/BUILD/gcc-4.8.2-20131212/obj-x86_64-redhat-linux/isl-install
--with-cloog=/builddir/build/BUILD/gcc-4.8.2-20131212/obj-x86_64-redhat-linux/cloog-install
--with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.8.2 20131212 (Red Hat 4.8.2-7) (GCC) 
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-D' '__LZCNT__' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'
 /usr/libexec/gcc/x86_64-redhat-linux/4.8.2/cc1plus -E -quiet -v -D_GNU_SOURCE
-D __LZCNT__ bug.cc -mtune=generic -march=x86-64 -fpch-preprocess -o bug.ii
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-redhat-linux/4.8.2/include-fixed"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-redhat-linux/4.8.2/../../../../x86_64-redhat-linux/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-redhat-linux/4.8.2/../../../../include/c++/4.8.2

/usr/lib/gcc/x86_64-redhat-linux/4.8.2/../../../../include/c++/4.8.2/x86_64-redhat-linux
 /usr/lib/gcc/x86_64-redhat-linux/4.8.2/../../../../include/c++/4.8.2/backward
 /usr/lib/gcc/x86_64-redhat-linux/4.8.2/include
 /usr/local/include
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-D' '__LZCNT__' '-shared-libgcc'
'-mtune=generic' '-march=x86-64'
 /usr/libexec/gcc/x86_64-redhat-linux/4.8.2/cc1plus -fpreprocessed bug.ii
-quiet -dumpbase bug.cc -mtune=generic -march=x86-64 -auxbase bug -version -o
bug.s
GNU C++ (GCC) version 4.8.2 20131212 (Red Hat 4.8.2-7) (x86_64-redhat-linux)
compiled by GNU C version 4.8.2 20131212 (Red Hat 4.8.2-7), GMP version
5.1.1, MPFR version 3.1.1, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++ (GCC) version 4.8.2 20131212 (Red Hat 4.8.2-7) (x86_64-redhat-linux)
compiled by GNU C version 4.8.2 20131212 (Red Hat 4.8.2-7), GMP version
5.1.1, MPFR version 3.1.1, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 489f772b6d0264e1e4c03fca513f7a0d
In file included from
/usr/lib/gcc/x86_64-redhat-linux/4.8.2/include/immintrin.h:64:0,
 from
/usr/lib/gcc/x86_64-redhat-linux/4.8.2/include/x86intrin.h:62,
 from bug.cc:1:
/usr/lib/gcc/x86_64-redhat-linux/4.8.2/include/lzcntintrin.h: In function
‘short unsigned int __lzcnt16(short unsigned int)’:
/usr/lib/gcc/x86_64-redhat-linux/4.8.2/include/lzcntintrin.h:38:29: error:
‘__builtin_clzs’ was not declared in this scope
   return __builtin_clzs (__X);

[Bug target/58928] Different results from gcc when -mlzcnt is used

2014-01-20 Thread mikeb01 at gmail dot com 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58928

Michael Barker  changed:

   What|Removed |Added

 Status|UNCONFIRMED |RESOLVED
 Resolution|--- |FIXED

--- Comment #6 from Michael Barker  ---
Not a bug, closed by reporter.

[Bug target/58928] Different results from gcc when -mlzcnt is used

2014-01-20 Thread mikeb01 at gmail dot com 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58928

Michael Barker  changed:

   What|Removed |Added

 Resolution|FIXED   |INVALID