[Bug c/60220] New: Vectorization : simple loop : fails to vectorize
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60220
Bug ID: 60220
Summary: Vectorization : simple loop : fails to vectorize
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: harmeeksingh at gmail dot com
#include
#include
#define FALSE ((char )0)
struct test
{
int*copy;
};
typedef struct test test;
void
foo(test *__restrict c, unsigned int a, unsigned int num)
{
unsigned int cnt;
for (cnt = 0; cnt < num ; cnt++)
c->copy[cnt] = FALSE;
for (cnt = 0; cnt < num ; cnt++)
printf("%u \n", c->copy[cnt]);
}
$ gcc -ggdb -O6 -march=native -pipe -fno-strict-aliasing -funroll-all-loops
-fpeel-loops -unroll-loops --param max-unroll-times=4 -ffast-math -fpeel-loops
-fwrapv -fPIC -pthread -rdynamic -DCLS=64 -mfpmath=sse -mmmx -msse -msse2
-msse3 -mssse3 -msse4.1 -msse4.2 -msse4 -ftree-vectorize
-ftree-vectorizer-verbose=7 -fgraphite-identity -falign-functions=4
-falign-loops=4 -falign-jumps=4 -fexpensive-optimizations
-frerun-cse-after-loop -frerun-loop-opt -finline-functions -o /tmp/x.o -c
/tmp/x.c
Analyzing loop at /tmp/x.c:18
18: not vectorized: loop contains function calls or data references that cannot
be analyzed
Analyzing loop at /tmp/x.c:16
16: not vectorized: data ref analysis failed *D.2523_9 = 0;
16: not vectorized: data ref analysis failed *D.2523_9 = 0;
/tmp/x.c:13: note: vectorized 0 loops in function.
Gcc - version
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.7.2/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 --disable-build-with-cxx
--disable-build-poststage1-with-cxx --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-ppl --with-cloog --with-tune=generic --with-arch_32=i686
--build=x86_64-redhat-linux
Thread model: posix
gcc version 4.7.2 20120921 (Red Hat 4.7.2-2) (GCC)
[Bug c/60220] Vectorization : simple loop : fails to vectorize
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60220
--- Comment #3 from harmeeksingh at gmail dot com ---
It still does not vectorise after adding the recomended flag. But rewriting the
code the following way does.
This is a bizare behavioir . My tests show that this is not an issue of gcc
rewriting it as a memset . If I change the value 0 to a array assignment it
still gives. From the output it does show that it is trying to assign FALSE.
31: not vectorized: data ref analysis failed *D.2549_9 = 0;
31: not vectorized: data ref analysis failed *D.2549_9 = 0;
#include
#include
#define FALSE ((char )0)
struct test
{
int*copy;
};
typedef struct test test;
static inline
foo1(int *a, unsigned int num)
{
unsigned int cnt;
for (cnt = 0; cnt < num ; cnt++)
a[cnt] = FALSE;
}
typedef uintptr_t Datum;
void
foo(test *__restrict c, unsigned int a, unsigned int num)
{
foo1(c->copy, num); // This vectorizes. if we pass it to inline function
}
[Bug c/61938] New: Vectorization not happening .
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61938
Bug ID: 61938
Summary: Vectorization not happening .
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: harmeeksingh at gmail dot com
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.7.2/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 --disable-build-with-cxx
--disable-build-poststage1-with-cxx --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-ppl --with-cloog --with-tune=generic --with-arch_32=i686
--build=x86_64-redhat-linux
Thread model: posix
gcc version 4.7.2 20120921 (Red Hat 4.7.2-2) (GCC)
Testcase
#include
#define VEC 1024
typedef long int int64;
typedef int int32;
void foo (int arraysize,
int *result,
int *selectvector,
int selectelements,
int32 *array,
int32 compval)
{
int k, i;
for (k =0,i=0; i < selectelements; ++i) {
result[k] = selectvector[i]; k += (((array[selectvector[i]])) ==
compval);
}
}
main()
{
int result[VEC];
int selectvector[VEC];
int selectelements;
int32 array[VEC];
int k, i;
foo(VEC, &result[0], &selectvector[0], VEC, &array[0], 1);
}
Compilation log
gcc -fPIC -ggdb -O3 -march=native -ftree-vectorize -ftree-vectorizer-verbose=7
/tmp/x.c -o /tmp/x
Analyzing loop at /tmp/x.c:17
17: not vectorized: data ref analysis failed *D.2502_9 = D.2506_14;
17: not vectorized: data ref analysis failed *D.2502_9 = D.2506_14;
/tmp/x.c:9: note: vectorized 0 loops in function.
[Bug tree-optimization/61938] Vectorization not happening .
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61938
--- Comment #3 from harmeeksingh at gmail dot com ---
#include
#define VEC 1024
typedef long int int64;
typedef int int32;
void foo (int arraysize,
int *__restrict result,
int *__restrict selectvector,
int selectelements,
int64 *__restrict array,
int64 compval)
{
int k, i;
for (k =0,i=0; i < arraysize; ++i) {
result[k] = i; k += (array[i] == compval);
}
}
main()
{
int result[VEC];
int selectvector[VEC];
int selectelements;
int64 array[VEC];
int k, i;
foo(VEC, result, selectvector, VEC, array, 1);
}
Even the above does not vectorize
gcc -fPIC -shared -DCLS=64 -ffast-math -mfpmath=sse -mmmx -msse -msse2
-ftree-vectorize -ftree-vectorizer-verbose=7 -O3 -march=native /tmp/x.c -o
/tmp/x
Analyzing loop at /tmp/x.c:17
17: not vectorized: data ref analysis failed *D.2502_9 = i_27;
/tmp/x.c:9: note: vectorized 0 loops in function.
[Bug tree-optimization/61938] Vectorization not happening .
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61938
--- Comment #6 from harmeeksingh at gmail dot com ---
Equivalent code when written by hand where tmp is a intermediate array . The
compiler
vectorizes both loops.
int k, i;
/* vectorize the compares */
for (i=0; i < arraysize; ++i) {
tmp[i] = (array[i] == compval);
}
/* another loop now set the result array */
for (k=0, i=0; i < arraysize; ++i) {
if (tmp[i])
{
result[k] = i;
k++;
}
}
