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Craig Topper via llvm-dev

2017-Aug-17 18:44 UTC

[llvm-dev] unable to emit vectorized code in LLVM IR

I assume compiler knows that your only have 2 input values that you just
added together 1000 times.

Despite the fact that you stored to a[i] and b[i] here, nothing reads them
other than the addition in the same loop iteration. So the compiler easily
removed the a and b arrays. Same with 'c', it's not read outside the
loop
so it doesn't need to exist. So the compiler turned your loop body back
into g+= aa + bb; And since the loop is 1000 iterations and aa and bb never
change this got further simplified to (aa+bb)*1000.

int main(int argc, char** argv) {
int a[1000], b[1000], c[1000]; int g=0;
int aa=atoi(argv[1]), bb=atoi(argv[2]);
for (int i=0; i<1000; i++) {
a[i]=aa, b[i]=bb;
 c[i]=a[i] + b[i];
g+=c[i];
}

~Craig

On Thu, Aug 17, 2017 at 11:37 AM, hameeza ahmed <hahmed2305 at gmail.com>
wrote:
> why is it happening? is there any way to solve this?
>
> On Thu, Aug 17, 2017 at 10:09 PM, hameeza ahmed <hahmed2305 at
gmail.com>
> wrote:
>
>> even if i make my code as follows: vectorized instructions not get
>> emitted. What to do?
>>
>> int main(int argc, char** argv) {
>> int a[1000], b[1000], c[1000]; int g=0;
>> int aa=atoi(argv[1]), bb=atoi(argv[2]);
>> for (int i=0; i<1000; i++) {
>> a[i]=aa, b[i]=bb;
>>  c[i]=a[i] + b[i];
>> g+=c[i];
>> }
>>
>> printf("sum: %d\n", g);
>>
>> return 0;
>> }
>>
>> On Thu, Aug 17, 2017 at 10:03 PM, Craig Topper <craig.topper at
gmail.com>
>> wrote:
>>
>>> Did you remove the printf completely? Meaning that nothing accesses
'c'
>>> after the loop? If so it got removed as dead code because it had no
visible
>>> effect.
>>>
>>> ~Craig
>>>
>>> On Thu, Aug 17, 2017 at 10:01 AM, hameeza ahmed <hahmed2305 at
gmail.com>
>>> wrote:
>>>
>>>> i removed printf from loop. Now getting no error. but the IR
doesnot
>>>> contain vectorized code. IR Output is as follows:
>>>> ; ModuleID = 'sum-vec.ll'
>>>> source_filename = "sum-vec.c"
>>>> target datalayout =
"e-m:e-i64:64-f80:128-n8:16:32:64-S128"
>>>> target triple = "x86_64-unknown-linux-gnu"
>>>>
>>>> ; Function Attrs: norecurse nounwind readnone uwtable
>>>> define i32 @main(i32, i8** nocapture readnone)
local_unnamed_addr #0 {
>>>>   ret i32 0
>>>> }
>>>>
>>>> attributes #0 = { norecurse nounwind readnone uwtable
>>>>
"correctly-rounded-divide-sqrt-fp-math"="false"
>>>> "disable-tail-calls"="false"
"less-precise-fpmad"="false"
>>>> "no-frame-pointer-elim"="false"
"no-infs-fp-math"="false"
>>>> "no-jump-tables"="false"
"no-nans-fp-math"="false"
>>>> "no-signed-zeros-fp-math"="false"
"no-trapping-math"="false"
>>>> "stack-protector-buffer-size"="8"
"target-cpu"="knl"
>>>>
"target-features"="+adx,+aes,+avx,+avx2,+avx512cd,+avx512er,
>>>> +avx512f,+avx512pf,+bmi,+bmi2,+cx16,+f16c,+fma,+fsgsbase,+fx
>>>> sr,+lzcnt,+mmx,+movbe,+pclmul,+popcnt,+prefetchwt1,+rdrnd,+r
>>>>
dseed,+rtm,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt"
>>>> "unsafe-fp-math"="false"
"use-soft-float"="false" }
>>>>
>>>> !llvm.ident = !{!0}
>>>>
>>>> !0 = !{!"clang version 4.0.0
(tags/RELEASE_400/final)"}
>>>>
>>>> what to do? please help.
>>>>
>>>>
>>>> On Thu, Aug 17, 2017 at 9:57 PM, Nemanja Ivanovic <
>>>> nemanja.i.ibm at gmail.com> wrote:
>>>>
>>>>> Move the printf out of the loop and it should vectorize
just fine.
>>>>>
>>>>> On Thu, Aug 17, 2017 at 6:52 PM, hameeza ahmed
<hahmed2305 at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> I want to vectorize the user given inputs. when opt
does
>>>>>> vectorization user supplied inputs (from a text file)
will be added using
>>>>>> AVX vector instructions.
>>>>>>
>>>>>> as you pointed; When i changed my code to following:
>>>>>>
>>>>>> int main(int argc, char** argv) {
>>>>>> int a[1000], b[1000], c[1000];
>>>>>> int aa=atoi(argv[1]), bb=atoi(argv[2]);
>>>>>> for (int i=0; i<1000; i++) {
>>>>>> a[i]=aa, b[i]=bb;
>>>>>>  c[i]=a[i] + b[i];
>>>>>> printf("sum: %d\n", c[i]);
>>>>>>
>>>>>> }
>>>>>>
>>>>>> I am getting error remark: <unknown>:0:0: loop
not vectorized: call
>>>>>> instruction cannot be vectorized.
>>>>>>
>>>>>> I am running following commands:
>>>>>> clang  -S -emit-llvm sum-vec.c -march=knl -O3 -mllvm
>>>>>> -disable-llvm-optzns -o sum-vec.ll
>>>>>> opt  -S -O3 -force-vector-width=64 sum-vec.ll -o
sum-vec03.ll
>>>>>>
>>>>>> How to achieve this? Please help.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Thu, Aug 17, 2017 at 10:44 AM, Nemanja Ivanovic <
>>>>>> nemanja.i.ibm at gmail.com> wrote:
>>>>>>
>>>>>>> I'm not sure what you expect to have vectorized
here. If you look at
>>>>>>> the emitted code, there's no loop. It's
just an add and a multiply as you
>>>>>>> might expect when adding a loop-invariant sum 1000
times in a loop.
>>>>>>>
>>>>>>> On Wed, Aug 16, 2017 at 11:38 PM, hameeza ahmed via
llvm-dev <
>>>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>>>
>>>>>>>> Hello,
>>>>>>>> I have written the following code. when i try
to vectorize it
>>>>>>>> through opt. i am not getting vectorized
instructions.
>>>>>>>>
>>>>>>>> #include <stdio.h>
>>>>>>>> #include<stdlib.h>
>>>>>>>> int main(int argc, char** argv) {
>>>>>>>> int sum=0; int a=atoi(argv[1]); int
b=atoi(argv[2]);
>>>>>>>> for (int i=0;i<1000;i++)
>>>>>>>> {
>>>>>>>> sum+=a+b;
>>>>>>>> }
>>>>>>>>
>>>>>>>> printf("sum: %d\n", sum);
>>>>>>>> return 0;
>>>>>>>> }
>>>>>>>> i use following commands:
>>>>>>>> clang  -S -emit-llvm sum-main.c -march=knl -O3
-mllvm
>>>>>>>> -disable-llvm-optzns -o sum-main.ll
>>>>>>>> opt  -S -O3 -force-vector-width=64 sum-main.ll
-o sum-main03.ll
>>>>>>>>
>>>>>>>> why is that so? where am i doing mistake? i am
not getting
>>>>>>>> vectorized operations rather getting scalar
operations.
>>>>>>>>
>>>>>>>> Please help.
>>>>>>>>
>>>>>>>> Thank You
>>>>>>>>
>>>>>>>> Regards
>>>>>>>>
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> LLVM Developers mailing list
>>>>>>>> llvm-dev at lists.llvm.org
>>>>>>>>
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
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hameeza ahmed via llvm-dev

2017-Aug-17 18:51 UTC

head link

[llvm-dev] unable to emit vectorized code in LLVM IR

when i change it to following: then get error: remark: <unknown>:0:0: loop
not vectorized: call instruction cannot be vectorized
int main(int argc, char** argv) {
int a[1000], b[1000], c[1000]; int g=0;
for (int i=0; i<1000; i++) {
a[i]=atoi(argv[1]), b[i]=atoi(argv[2]);
 c[i]=a[i] + b[i];
g+=c[i];
}

Here my main goal is that i need to use JIT to perform operations on user
input file supplied at run time using vector instructions. is it possible
and achievable through JIT?
Please help.



On Thu, Aug 17, 2017 at 11:44 PM, Craig Topper <craig.topper at gmail.com>
wrote:
> I assume compiler knows that your only have 2 input values that you just
> added together 1000 times.
>
> Despite the fact that you stored to a[i] and b[i] here, nothing reads them
> other than the addition in the same loop iteration. So the compiler easily
> removed the a and b arrays. Same with 'c', it's not read
outside the loop
> so it doesn't need to exist. So the compiler turned your loop body back
> into g+= aa + bb; And since the loop is 1000 iterations and aa and bb never
> change this got further simplified to (aa+bb)*1000.
>
> int main(int argc, char** argv) {
> int a[1000], b[1000], c[1000]; int g=0;
> int aa=atoi(argv[1]), bb=atoi(argv[2]);
> for (int i=0; i<1000; i++) {
> a[i]=aa, b[i]=bb;
>  c[i]=a[i] + b[i];
> g+=c[i];
> }
>
> ~Craig
>
> On Thu, Aug 17, 2017 at 11:37 AM, hameeza ahmed <hahmed2305 at
gmail.com>
> wrote:
>
>> why is it happening? is there any way to solve this?
>>
>> On Thu, Aug 17, 2017 at 10:09 PM, hameeza ahmed <hahmed2305 at
gmail.com>
>> wrote:
>>
>>> even if i make my code as follows: vectorized instructions not get
>>> emitted. What to do?
>>>
>>> int main(int argc, char** argv) {
>>> int a[1000], b[1000], c[1000]; int g=0;
>>> int aa=atoi(argv[1]), bb=atoi(argv[2]);
>>> for (int i=0; i<1000; i++) {
>>> a[i]=aa, b[i]=bb;
>>>  c[i]=a[i] + b[i];
>>> g+=c[i];
>>> }
>>>
>>> printf("sum: %d\n", g);
>>>
>>> return 0;
>>> }
>>>
>>> On Thu, Aug 17, 2017 at 10:03 PM, Craig Topper <craig.topper at
gmail.com>
>>> wrote:
>>>
>>>> Did you remove the printf completely? Meaning that nothing
accesses 'c'
>>>> after the loop? If so it got removed as dead code because it
had no visible
>>>> effect.
>>>>
>>>> ~Craig
>>>>
>>>> On Thu, Aug 17, 2017 at 10:01 AM, hameeza ahmed <hahmed2305
at gmail.com>
>>>> wrote:
>>>>
>>>>> i removed printf from loop. Now getting no error. but the
IR doesnot
>>>>> contain vectorized code. IR Output is as follows:
>>>>> ; ModuleID = 'sum-vec.ll'
>>>>> source_filename = "sum-vec.c"
>>>>> target datalayout =
"e-m:e-i64:64-f80:128-n8:16:32:64-S128"
>>>>> target triple = "x86_64-unknown-linux-gnu"
>>>>>
>>>>> ; Function Attrs: norecurse nounwind readnone uwtable
>>>>> define i32 @main(i32, i8** nocapture readnone)
local_unnamed_addr #0 {
>>>>>   ret i32 0
>>>>> }
>>>>>
>>>>> attributes #0 = { norecurse nounwind readnone uwtable
>>>>>
"correctly-rounded-divide-sqrt-fp-math"="false"
>>>>> "disable-tail-calls"="false"
"less-precise-fpmad"="false"
>>>>> "no-frame-pointer-elim"="false"
"no-infs-fp-math"="false"
>>>>> "no-jump-tables"="false"
"no-nans-fp-math"="false"
>>>>> "no-signed-zeros-fp-math"="false"
"no-trapping-math"="false"
>>>>> "stack-protector-buffer-size"="8"
"target-cpu"="knl"
>>>>>
"target-features"="+adx,+aes,+avx,+avx2,+avx512cd,+avx512er,
>>>>>
+avx512f,+avx512pf,+bmi,+bmi2,+cx16,+f16c,+fma,+fsgsbase,+fx
>>>>>
sr,+lzcnt,+mmx,+movbe,+pclmul,+popcnt,+prefetchwt1,+rdrnd,+r
>>>>>
dseed,+rtm,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt"
>>>>> "unsafe-fp-math"="false"
"use-soft-float"="false" }
>>>>>
>>>>> !llvm.ident = !{!0}
>>>>>
>>>>> !0 = !{!"clang version 4.0.0
(tags/RELEASE_400/final)"}
>>>>>
>>>>> what to do? please help.
>>>>>
>>>>>
>>>>> On Thu, Aug 17, 2017 at 9:57 PM, Nemanja Ivanovic <
>>>>> nemanja.i.ibm at gmail.com> wrote:
>>>>>
>>>>>> Move the printf out of the loop and it should vectorize
just fine.
>>>>>>
>>>>>> On Thu, Aug 17, 2017 at 6:52 PM, hameeza ahmed
<hahmed2305 at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> I want to vectorize the user given inputs. when opt
does
>>>>>>> vectorization user supplied inputs (from a text
file) will be added using
>>>>>>> AVX vector instructions.
>>>>>>>
>>>>>>> as you pointed; When i changed my code to
following:
>>>>>>>
>>>>>>> int main(int argc, char** argv) {
>>>>>>> int a[1000], b[1000], c[1000];
>>>>>>> int aa=atoi(argv[1]), bb=atoi(argv[2]);
>>>>>>> for (int i=0; i<1000; i++) {
>>>>>>> a[i]=aa, b[i]=bb;
>>>>>>>  c[i]=a[i] + b[i];
>>>>>>> printf("sum: %d\n", c[i]);
>>>>>>>
>>>>>>> }
>>>>>>>
>>>>>>> I am getting error remark: <unknown>:0:0:
loop not vectorized: call
>>>>>>> instruction cannot be vectorized.
>>>>>>>
>>>>>>> I am running following commands:
>>>>>>> clang  -S -emit-llvm sum-vec.c -march=knl -O3
-mllvm
>>>>>>> -disable-llvm-optzns -o sum-vec.ll
>>>>>>> opt  -S -O3 -force-vector-width=64 sum-vec.ll -o
sum-vec03.ll
>>>>>>>
>>>>>>> How to achieve this? Please help.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Aug 17, 2017 at 10:44 AM, Nemanja Ivanovic
<
>>>>>>> nemanja.i.ibm at gmail.com> wrote:
>>>>>>>
>>>>>>>> I'm not sure what you expect to have
vectorized here. If you look
>>>>>>>> at the emitted code, there's no loop.
It's just an add and a multiply as
>>>>>>>> you might expect when adding a loop-invariant
sum 1000 times in a loop.
>>>>>>>>
>>>>>>>> On Wed, Aug 16, 2017 at 11:38 PM, hameeza ahmed
via llvm-dev <
>>>>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>>>>
>>>>>>>>> Hello,
>>>>>>>>> I have written the following code. when i
try to vectorize it
>>>>>>>>> through opt. i am not getting vectorized
instructions.
>>>>>>>>>
>>>>>>>>> #include <stdio.h>
>>>>>>>>> #include<stdlib.h>
>>>>>>>>> int main(int argc, char** argv) {
>>>>>>>>> int sum=0; int a=atoi(argv[1]); int
b=atoi(argv[2]);
>>>>>>>>> for (int i=0;i<1000;i++)
>>>>>>>>> {
>>>>>>>>> sum+=a+b;
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> printf("sum: %d\n", sum);
>>>>>>>>> return 0;
>>>>>>>>> }
>>>>>>>>> i use following commands:
>>>>>>>>> clang  -S -emit-llvm sum-main.c -march=knl
-O3 -mllvm
>>>>>>>>> -disable-llvm-optzns -o sum-main.ll
>>>>>>>>> opt  -S -O3 -force-vector-width=64
sum-main.ll -o sum-main03.ll
>>>>>>>>>
>>>>>>>>> why is that so? where am i doing mistake? i
am not getting
>>>>>>>>> vectorized operations rather getting scalar
operations.
>>>>>>>>>
>>>>>>>>> Please help.
>>>>>>>>>
>>>>>>>>> Thank You
>>>>>>>>>
>>>>>>>>> Regards
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
_______________________________________________
>>>>>>>>> LLVM Developers mailing list
>>>>>>>>> llvm-dev at lists.llvm.org
>>>>>>>>>
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
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Francois Fayard via llvm-dev

2017-Aug-17 18:51 UTC

head link

[llvm-dev] unable to emit vectorized code in LLVM IR

Try that:

void f(int* a, int* b, int* c, int n) {
  for (int i = 0; i < n; ++i) {
    c[i] = a[i] + b[i];
  }
}

and compile with: clang++ -S -O3 -mavx2 a.cpp -o a.assembly
and look at the a.assembly file. You’ll get something such as:

LBB0_12:                                ## =>This Inner Loop Header: Depth=1
	vmovdqu	-96(%rax), %ymm0
	vmovdqu	-64(%rax), %ymm1
	vmovdqu	-32(%rax), %ymm2
	vmovdqu	(%rax), %ymm3
	vpaddd	-96(%r11), %ymm0, %ymm0
	vpaddd	-64(%r11), %ymm1, %ymm1
	vpaddd	-32(%r11), %ymm2, %ymm2
	vpaddd	(%r11), %ymm3, %ymm3
	vmovdqu	%ymm0, -96(%rbx)
	vmovdqu	%ymm1, -64(%rbx)
	vmovdqu	%ymm2, -32(%rbx)
	vmovdqu	%ymm3, (%rbx)
	subq	$-128, %r11
	subq	$-128, %rax
	subq	$-128, %rbx
	addq	$-32, %r9
	jne	LBB0_12

That’s vectorized code, unrolled by 4. So you get 4 * (32 / 4) = 32 elements
processed every loop. The ymm registers shows that you are using 256 bits vector
registers as available on avx cpu. With avx512, you would get zmm registers.

François Fayard
> On Aug 17, 2017, at 8:44 PM, Craig Topper via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> I assume compiler knows that your only have 2 input values that you just
added together 1000 times.
> 
> Despite the fact that you stored to a[i] and b[i] here, nothing reads them
other than the addition in the same loop iteration. So the compiler easily
removed the a and b arrays. Same with 'c', it's not read outside the
loop so it doesn't need to exist. So the compiler turned your loop body back
into g+= aa + bb; And since the loop is 1000 iterations and aa and bb never
change this got further simplified to (aa+bb)*1000.
> 
> int main(int argc, char** argv) {
> int a[1000], b[1000], c[1000]; int g=0;
> int aa=atoi(argv[1]), bb=atoi(argv[2]);
> for (int i=0; i<1000; i++) {
> a[i]=aa, b[i]=bb;
>  c[i]=a[i] + b[i];
> g+=c[i];
> }
> 
> ~Craig
> 
> On Thu, Aug 17, 2017 at 11:37 AM, hameeza ahmed <hahmed2305 at gmail.com
<mailto:hahmed2305 at gmail.com>> wrote:
> why is it happening? is there any way to solve this?
> 
> On Thu, Aug 17, 2017 at 10:09 PM, hameeza ahmed <hahmed2305 at gmail.com
<mailto:hahmed2305 at gmail.com>> wrote:
> even if i make my code as follows: vectorized instructions not get emitted.
What to do?
> 
> int main(int argc, char** argv) {
> int a[1000], b[1000], c[1000]; int g=0;
> int aa=atoi(argv[1]), bb=atoi(argv[2]);
> for (int i=0; i<1000; i++) {
> a[i]=aa, b[i]=bb;
>  c[i]=a[i] + b[i];
> g+=c[i];
> }
> 
> printf("sum: %d\n", g);
> 
> return 0;
> }
> 
> On Thu, Aug 17, 2017 at 10:03 PM, Craig Topper <craig.topper at
gmail.com <mailto:craig.topper at gmail.com>> wrote:
> Did you remove the printf completely? Meaning that nothing accesses
'c' after the loop? If so it got removed as dead code because it had no
visible effect.
> 
> ~Craig
> 
> On Thu, Aug 17, 2017 at 10:01 AM, hameeza ahmed <hahmed2305 at gmail.com
<mailto:hahmed2305 at gmail.com>> wrote:
> i removed printf from loop. Now getting no error. but the IR doesnot
contain vectorized code. IR Output is as follows:
> ; ModuleID = 'sum-vec.ll'
> source_filename = "sum-vec.c"
> target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
> target triple = "x86_64-unknown-linux-gnu"
> 
> ; Function Attrs: norecurse nounwind readnone uwtable
> define i32 @main(i32, i8** nocapture readnone) local_unnamed_addr #0 {
>   ret i32 0
> }
> 
> attributes #0 = { norecurse nounwind readnone uwtable
"correctly-rounded-divide-sqrt-fp-math"="false"
"disable-tail-calls"="false"
"less-precise-fpmad"="false"
"no-frame-pointer-elim"="false"
"no-infs-fp-math"="false"
"no-jump-tables"="false"
"no-nans-fp-math"="false"
"no-signed-zeros-fp-math"="false"
"no-trapping-math"="false"
"stack-protector-buffer-size"="8"
"target-cpu"="knl"
"target-features"="+adx,+aes,+avx,+avx2,+avx512cd,+avx512er,+avx512f,+avx512pf,+bmi,+bmi2,+cx16,+f16c,+fma,+fsgsbase,+fxsr,+lzcnt,+mmx,+movbe,+pclmul,+popcnt,+prefetchwt1,+rdrnd,+rdseed,+rtm,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt"
"unsafe-fp-math"="false"
"use-soft-float"="false" }
> 
> !llvm.ident = !{!0}
> 
> !0 = !{!"clang version 4.0.0 (tags/RELEASE_400/final)"}
> 
> what to do? please help.
> 
> 
> On Thu, Aug 17, 2017 at 9:57 PM, Nemanja Ivanovic <nemanja.i.ibm at
gmail.com <mailto:nemanja.i.ibm at gmail.com>> wrote:
> Move the printf out of the loop and it should vectorize just fine.
> 
> On Thu, Aug 17, 2017 at 6:52 PM, hameeza ahmed <hahmed2305 at gmail.com
<mailto:hahmed2305 at gmail.com>> wrote:
> I want to vectorize the user given inputs. when opt does vectorization user
supplied inputs (from a text file) will be added using AVX vector instructions.
> 
> as you pointed; When i changed my code to following:
> 
> int main(int argc, char** argv) {
> int a[1000], b[1000], c[1000];
> int aa=atoi(argv[1]), bb=atoi(argv[2]);
> for (int i=0; i<1000; i++) {
> a[i]=aa, b[i]=bb;
>  c[i]=a[i] + b[i];
> printf("sum: %d\n", c[i]);
> 
> }
> 
> I am getting error remark: <unknown>:0:0: loop not vectorized: call
instruction cannot be vectorized.
> 
> I am running following commands:
> clang  -S -emit-llvm sum-vec.c -march=knl -O3 -mllvm -disable-llvm-optzns
-o sum-vec.ll
> opt  -S -O3 -force-vector-width=64 sum-vec.ll -o sum-vec03.ll
> 
> How to achieve this? Please help.
> 
> 
> 
> 
> 
> On Thu, Aug 17, 2017 at 10:44 AM, Nemanja Ivanovic <nemanja.i.ibm at
gmail.com <mailto:nemanja.i.ibm at gmail.com>> wrote:
> I'm not sure what you expect to have vectorized here. If you look at
the emitted code, there's no loop. It's just an add and a multiply as
you might expect when adding a loop-invariant sum 1000 times in a loop.
> 
> On Wed, Aug 16, 2017 at 11:38 PM, hameeza ahmed via llvm-dev <llvm-dev
at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
> Hello, 
> I have written the following code. when i try to vectorize it through opt.
i am not getting vectorized instructions.
> 
> #include <stdio.h>
> #include<stdlib.h>
> int main(int argc, char** argv) {
> int sum=0; int a=atoi(argv[1]); int b=atoi(argv[2]);
> for (int i=0;i<1000;i++)
> {
> sum+=a+b;
> }
> 
> printf("sum: %d\n", sum);
> return 0;
> }
> i use following commands:
> clang  -S -emit-llvm sum-main.c -march=knl -O3 -mllvm -disable-llvm-optzns
-o sum-main.ll
> opt  -S -O3 -force-vector-width=64 sum-main.ll -o sum-main03.ll
> 
> why is that so? where am i doing mistake? i am not getting vectorized
operations rather getting scalar operations.
> 
> Please help.
> 
> Thank You
> 
> Regards
> 
> 
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
<http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> 
> 
> 
> 
> 
> 
> 
> 
> 
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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Craig Topper via llvm-dev

2017-Aug-17 18:56 UTC

head link

[llvm-dev] unable to emit vectorized code in LLVM IR

By accessing only argv[1] and argv[2], you only took 2 numbers from the
command line as input and added them together over and over again. You need
to open a file and read nubmers from it or access more command line
parameters.

~Craig

On Thu, Aug 17, 2017 at 11:51 AM, Francois Fayard via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Try that:
>
> void f(int* a, int* b, int* c, int n) {
>   for (int i = 0; i < n; ++i) {
>     c[i] = a[i] + b[i];
>   }
> }
>
> and compile with: clang++ -S -O3 -mavx2 a.cpp -o a.assembly
> and look at the a.assembly file. You’ll get something such as:
>
> LBB0_12:                                ## =>This Inner Loop
> Header: Depth=1
> vmovdqu -96(%rax), %ymm0
> vmovdqu -64(%rax), %ymm1
> vmovdqu -32(%rax), %ymm2
> vmovdqu (%rax), %ymm3
> vpaddd -96(%r11), %ymm0, %ymm0
> vpaddd -64(%r11), %ymm1, %ymm1
> vpaddd -32(%r11), %ymm2, %ymm2
> vpaddd (%r11), %ymm3, %ymm3
> vmovdqu %ymm0, -96(%rbx)
> vmovdqu %ymm1, -64(%rbx)
> vmovdqu %ymm2, -32(%rbx)
> vmovdqu %ymm3, (%rbx)
> subq $-128, %r11
> subq $-128, %rax
> subq $-128, %rbx
> addq $-32, %r9
> jne LBB0_12
>
> That’s vectorized code, unrolled by 4. So you get 4 * (32 / 4) = 32
> elements processed every loop. The ymm registers shows that you are using
> 256 bits vector registers as available on avx cpu. With avx512, you would
> get zmm registers.
>
> François Fayard
>
> On Aug 17, 2017, at 8:44 PM, Craig Topper via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> I assume compiler knows that your only have 2 input values that you just
> added together 1000 times.
>
> Despite the fact that you stored to a[i] and b[i] here, nothing reads them
> other than the addition in the same loop iteration. So the compiler easily
> removed the a and b arrays. Same with 'c', it's not read
outside the loop
> so it doesn't need to exist. So the compiler turned your loop body back
> into g+= aa + bb; And since the loop is 1000 iterations and aa and bb never
> change this got further simplified to (aa+bb)*1000.
>
> int main(int argc, char** argv) {
> int a[1000], b[1000], c[1000]; int g=0;
> int aa=atoi(argv[1]), bb=atoi(argv[2]);
> for (int i=0; i<1000; i++) {
> a[i]=aa, b[i]=bb;
>  c[i]=a[i] + b[i];
> g+=c[i];
> }
>
> ~Craig
>
> On Thu, Aug 17, 2017 at 11:37 AM, hameeza ahmed <hahmed2305 at
gmail.com>
> wrote:
>
>> why is it happening? is there any way to solve this?
>>
>> On Thu, Aug 17, 2017 at 10:09 PM, hameeza ahmed <hahmed2305 at
gmail.com>
>> wrote:
>>
>>> even if i make my code as follows: vectorized instructions not get
>>> emitted. What to do?
>>>
>>> int main(int argc, char** argv) {
>>> int a[1000], b[1000], c[1000]; int g=0;
>>> int aa=atoi(argv[1]), bb=atoi(argv[2]);
>>> for (int i=0; i<1000; i++) {
>>> a[i]=aa, b[i]=bb;
>>>  c[i]=a[i] + b[i];
>>> g+=c[i];
>>> }
>>>
>>> printf("sum: %d\n", g);
>>>
>>> return 0;
>>> }
>>>
>>> On Thu, Aug 17, 2017 at 10:03 PM, Craig Topper <craig.topper at
gmail.com>
>>> wrote:
>>>
>>>> Did you remove the printf completely? Meaning that nothing
accesses 'c'
>>>> after the loop? If so it got removed as dead code because it
had no visible
>>>> effect.
>>>>
>>>> ~Craig
>>>>
>>>> On Thu, Aug 17, 2017 at 10:01 AM, hameeza ahmed <hahmed2305
at gmail.com>
>>>> wrote:
>>>>
>>>>> i removed printf from loop. Now getting no error. but the
IR doesnot
>>>>> contain vectorized code. IR Output is as follows:
>>>>> ; ModuleID = 'sum-vec.ll'
>>>>> source_filename = "sum-vec.c"
>>>>> target datalayout =
"e-m:e-i64:64-f80:128-n8:16:32:64-S128"
>>>>> target triple = "x86_64-unknown-linux-gnu"
>>>>>
>>>>> ; Function Attrs: norecurse nounwind readnone uwtable
>>>>> define i32 @main(i32, i8** nocapture readnone)
local_unnamed_addr #0 {
>>>>>   ret i32 0
>>>>> }
>>>>>
>>>>> attributes #0 = { norecurse nounwind readnone uwtable
>>>>>
"correctly-rounded-divide-sqrt-fp-math"="false"
>>>>> "disable-tail-calls"="false"
"less-precise-fpmad"="false"
>>>>> "no-frame-pointer-elim"="false"
"no-infs-fp-math"="false"
>>>>> "no-jump-tables"="false"
"no-nans-fp-math"="false"
>>>>> "no-signed-zeros-fp-math"="false"
"no-trapping-math"="false"
>>>>> "stack-protector-buffer-size"="8"
"target-cpu"="knl"
>>>>>
"target-features"="+adx,+aes,+avx,+avx2,+avx512cd,+avx512er,
>>>>>
+avx512f,+avx512pf,+bmi,+bmi2,+cx16,+f16c,+fma,+fsgsbase,+fx
>>>>>
sr,+lzcnt,+mmx,+movbe,+pclmul,+popcnt,+prefetchwt1,+rdrnd,+r
>>>>>
dseed,+rtm,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt"
>>>>> "unsafe-fp-math"="false"
"use-soft-float"="false" }
>>>>>
>>>>> !llvm.ident = !{!0}
>>>>>
>>>>> !0 = !{!"clang version 4.0.0
(tags/RELEASE_400/final)"}
>>>>>
>>>>> what to do? please help.
>>>>>
>>>>>
>>>>> On Thu, Aug 17, 2017 at 9:57 PM, Nemanja Ivanovic <
>>>>> nemanja.i.ibm at gmail.com> wrote:
>>>>>
>>>>>> Move the printf out of the loop and it should vectorize
just fine.
>>>>>>
>>>>>> On Thu, Aug 17, 2017 at 6:52 PM, hameeza ahmed
<hahmed2305 at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> I want to vectorize the user given inputs. when opt
does
>>>>>>> vectorization user supplied inputs (from a text
file) will be added using
>>>>>>> AVX vector instructions.
>>>>>>>
>>>>>>> as you pointed; When i changed my code to
following:
>>>>>>>
>>>>>>> int main(int argc, char** argv) {
>>>>>>> int a[1000], b[1000], c[1000];
>>>>>>> int aa=atoi(argv[1]), bb=atoi(argv[2]);
>>>>>>> for (int i=0; i<1000; i++) {
>>>>>>> a[i]=aa, b[i]=bb;
>>>>>>>  c[i]=a[i] + b[i];
>>>>>>> printf("sum: %d\n", c[i]);
>>>>>>>
>>>>>>> }
>>>>>>>
>>>>>>> I am getting error remark: <unknown>:0:0:
loop not vectorized: call
>>>>>>> instruction cannot be vectorized.
>>>>>>>
>>>>>>> I am running following commands:
>>>>>>> clang  -S -emit-llvm sum-vec.c -march=knl -O3
-mllvm
>>>>>>> -disable-llvm-optzns -o sum-vec.ll
>>>>>>> opt  -S -O3 -force-vector-width=64 sum-vec.ll -o
sum-vec03.ll
>>>>>>>
>>>>>>> How to achieve this? Please help.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Aug 17, 2017 at 10:44 AM, Nemanja Ivanovic
<
>>>>>>> nemanja.i.ibm at gmail.com> wrote:
>>>>>>>
>>>>>>>> I'm not sure what you expect to have
vectorized here. If you look
>>>>>>>> at the emitted code, there's no loop.
It's just an add and a multiply as
>>>>>>>> you might expect when adding a loop-invariant
sum 1000 times in a loop.
>>>>>>>>
>>>>>>>> On Wed, Aug 16, 2017 at 11:38 PM, hameeza ahmed
via llvm-dev <
>>>>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>>>>
>>>>>>>>> Hello,
>>>>>>>>> I have written the following code. when i
try to vectorize it
>>>>>>>>> through opt. i am not getting vectorized
instructions.
>>>>>>>>>
>>>>>>>>> #include <stdio.h>
>>>>>>>>> #include<stdlib.h>
>>>>>>>>> int main(int argc, char** argv) {
>>>>>>>>> int sum=0; int a=atoi(argv[1]); int
b=atoi(argv[2]);
>>>>>>>>> for (int i=0;i<1000;i++)
>>>>>>>>> {
>>>>>>>>> sum+=a+b;
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> printf("sum: %d\n", sum);
>>>>>>>>> return 0;
>>>>>>>>> }
>>>>>>>>> i use following commands:
>>>>>>>>> clang  -S -emit-llvm sum-main.c -march=knl
-O3 -mllvm
>>>>>>>>> -disable-llvm-optzns -o sum-main.ll
>>>>>>>>> opt  -S -O3 -force-vector-width=64
sum-main.ll -o sum-main03.ll
>>>>>>>>>
>>>>>>>>> why is that so? where am i doing mistake? i
am not getting
>>>>>>>>> vectorized operations rather getting scalar
operations.
>>>>>>>>>
>>>>>>>>> Please help.
>>>>>>>>>
>>>>>>>>> Thank You
>>>>>>>>>
>>>>>>>>> Regards
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
_______________________________________________
>>>>>>>>> LLVM Developers mailing list
>>>>>>>>> llvm-dev at lists.llvm.org
>>>>>>>>>
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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hameeza ahmed via llvm-dev

2017-Aug-17 19:12 UTC

head link

[llvm-dev] unable to emit vectorized code in LLVM IR

Ok. I have managed to vectorize the second loop in the following code. But
the first loop is still not vectorized? Why?

int main(int argc, char** argv) {
int a[1000], b[1000], c[1000]; int g=0;
int aa=atoi(argv[1]), bb=atoi(argv[2]);

for (int i=0; i<1000; i++) {
a[i]=aa+i, b[i]=bb+i;}

for (int i=0; i<1000; i++) {
 c[i]=a[i] + b[i];
g+=c[i];
}

printf("sum: %d\n", g);

return 0;
}

When i executed the optimized IR through jit (lli sum-vec03.ll  5 2) i am
getting following error:

#0 0x00000000013f965c llvm::sys::PrintStackTrace(llvm::raw_ostream&)
/lib/Support/Unix/Signals.inc:402:11
#1 0x00000000013f9b49 PrintStackTraceSignalHandler(void*)
/lib/Support/Unix/Signals.inc:466:1
#2 0x00000000013f7ec3 llvm::sys::RunSignalHandlers()
/lib/Support/Signals.cpp:0:5
#3 0x00000000013f9ea4 SignalHandler(int) /lib/Support/Unix/Signals.inc:256:1
#4 0x00007fcdece96d10 __restore_rt
(/lib/x86_64-linux-gnu/libpthread.so.0+0x10d10)
#5 0x00007fcded2c3038
#6 0x0000000000f4a8fb llvm::MCJIT::runFunction(llvm::Function*,
llvm::ArrayRef<llvm::GenericValue>)
/lib/ExecutionEngine/MCJIT/MCJIT.cpp:538:31
#7 0x0000000000eaff23
llvm::ExecutionEngine::runFunctionAsMain(llvm::Function*,
std::vector<std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >,
std::allocator<std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> > > >
const&, char const*
const*) /lib/ExecutionEngine/ExecutionEngine.cpp:471:10
#8 0x00000000007be4e9 main /tools/lli/lli.cpp:627:18
#9 0x00007fcdebe2fa40 __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x20a40)
#10 0x00000000007bc169 _start (/bin/lli+0x7bc169)
Stack dump:
0. Program arguments:lli sum-vec03.ll 5 2
Illegal instruction (core dumped)


What is wrong here? please help.









On Thu, Aug 17, 2017 at 11:51 PM, hameeza ahmed <hahmed2305 at gmail.com>
wrote:
> when i change it to following: then get error: remark: <unknown>:0:0:
loop
> not vectorized: call instruction cannot be vectorized
> int main(int argc, char** argv) {
> int a[1000], b[1000], c[1000]; int g=0;
> for (int i=0; i<1000; i++) {
> a[i]=atoi(argv[1]), b[i]=atoi(argv[2]);
>  c[i]=a[i] + b[i];
> g+=c[i];
> }
>
> Here my main goal is that i need to use JIT to perform operations on user
> input file supplied at run time using vector instructions. is it possible
> and achievable through JIT?
> Please help.
>
>
>
> On Thu, Aug 17, 2017 at 11:44 PM, Craig Topper <craig.topper at
gmail.com>
> wrote:
>
>> I assume compiler knows that your only have 2 input values that you
just
>> added together 1000 times.
>>
>> Despite the fact that you stored to a[i] and b[i] here, nothing reads
>> them other than the addition in the same loop iteration. So the
compiler
>> easily removed the a and b arrays. Same with 'c', it's not
read outside the
>> loop so it doesn't need to exist. So the compiler turned your loop
body
>> back into g+= aa + bb; And since the loop is 1000 iterations and aa and
bb
>> never change this got further simplified to (aa+bb)*1000.
>>
>> int main(int argc, char** argv) {
>> int a[1000], b[1000], c[1000]; int g=0;
>> int aa=atoi(argv[1]), bb=atoi(argv[2]);
>> for (int i=0; i<1000; i++) {
>> a[i]=aa, b[i]=bb;
>>  c[i]=a[i] + b[i];
>> g+=c[i];
>> }
>>
>> ~Craig
>>
>> On Thu, Aug 17, 2017 at 11:37 AM, hameeza ahmed <hahmed2305 at
gmail.com>
>> wrote:
>>
>>> why is it happening? is there any way to solve this?
>>>
>>> On Thu, Aug 17, 2017 at 10:09 PM, hameeza ahmed <hahmed2305 at
gmail.com>
>>> wrote:
>>>
>>>> even if i make my code as follows: vectorized instructions not
get
>>>> emitted. What to do?
>>>>
>>>> int main(int argc, char** argv) {
>>>> int a[1000], b[1000], c[1000]; int g=0;
>>>> int aa=atoi(argv[1]), bb=atoi(argv[2]);
>>>> for (int i=0; i<1000; i++) {
>>>> a[i]=aa, b[i]=bb;
>>>>  c[i]=a[i] + b[i];
>>>> g+=c[i];
>>>> }
>>>>
>>>> printf("sum: %d\n", g);
>>>>
>>>> return 0;
>>>> }
>>>>
>>>> On Thu, Aug 17, 2017 at 10:03 PM, Craig Topper <craig.topper
at gmail.com>
>>>> wrote:
>>>>
>>>>> Did you remove the printf completely? Meaning that nothing
accesses
>>>>> 'c' after the loop? If so it got removed as dead
code because it had no
>>>>> visible effect.
>>>>>
>>>>> ~Craig
>>>>>
>>>>> On Thu, Aug 17, 2017 at 10:01 AM, hameeza ahmed
<hahmed2305 at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> i removed printf from loop. Now getting no error. but
the IR doesnot
>>>>>> contain vectorized code. IR Output is as follows:
>>>>>> ; ModuleID = 'sum-vec.ll'
>>>>>> source_filename = "sum-vec.c"
>>>>>> target datalayout =
"e-m:e-i64:64-f80:128-n8:16:32:64-S128"
>>>>>> target triple = "x86_64-unknown-linux-gnu"
>>>>>>
>>>>>> ; Function Attrs: norecurse nounwind readnone uwtable
>>>>>> define i32 @main(i32, i8** nocapture readnone)
local_unnamed_addr #0 {
>>>>>>   ret i32 0
>>>>>> }
>>>>>>
>>>>>> attributes #0 = { norecurse nounwind readnone uwtable
>>>>>>
"correctly-rounded-divide-sqrt-fp-math"="false"
>>>>>> "disable-tail-calls"="false"
"less-precise-fpmad"="false"
>>>>>> "no-frame-pointer-elim"="false"
"no-infs-fp-math"="false"
>>>>>> "no-jump-tables"="false"
"no-nans-fp-math"="false"
>>>>>> "no-signed-zeros-fp-math"="false"
"no-trapping-math"="false"
>>>>>> "stack-protector-buffer-size"="8"
"target-cpu"="knl"
>>>>>>
"target-features"="+adx,+aes,+avx,+avx2,+avx512cd,+avx512er,
>>>>>>
+avx512f,+avx512pf,+bmi,+bmi2,+cx16,+f16c,+fma,+fsgsbase,+fx
>>>>>>
sr,+lzcnt,+mmx,+movbe,+pclmul,+popcnt,+prefetchwt1,+rdrnd,+r
>>>>>>
dseed,+rtm,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt"
>>>>>> "unsafe-fp-math"="false"
"use-soft-float"="false" }
>>>>>>
>>>>>> !llvm.ident = !{!0}
>>>>>>
>>>>>> !0 = !{!"clang version 4.0.0
(tags/RELEASE_400/final)"}
>>>>>>
>>>>>> what to do? please help.
>>>>>>
>>>>>>
>>>>>> On Thu, Aug 17, 2017 at 9:57 PM, Nemanja Ivanovic <
>>>>>> nemanja.i.ibm at gmail.com> wrote:
>>>>>>
>>>>>>> Move the printf out of the loop and it should
vectorize just fine.
>>>>>>>
>>>>>>> On Thu, Aug 17, 2017 at 6:52 PM, hameeza ahmed
<hahmed2305 at gmail.com
>>>>>>> > wrote:
>>>>>>>
>>>>>>>> I want to vectorize the user given inputs. when
opt does
>>>>>>>> vectorization user supplied inputs (from a text
file) will be added using
>>>>>>>> AVX vector instructions.
>>>>>>>>
>>>>>>>> as you pointed; When i changed my code to
following:
>>>>>>>>
>>>>>>>> int main(int argc, char** argv) {
>>>>>>>> int a[1000], b[1000], c[1000];
>>>>>>>> int aa=atoi(argv[1]), bb=atoi(argv[2]);
>>>>>>>> for (int i=0; i<1000; i++) {
>>>>>>>> a[i]=aa, b[i]=bb;
>>>>>>>>  c[i]=a[i] + b[i];
>>>>>>>> printf("sum: %d\n", c[i]);
>>>>>>>>
>>>>>>>> }
>>>>>>>>
>>>>>>>> I am getting error remark: <unknown>:0:0:
loop not vectorized: call
>>>>>>>> instruction cannot be vectorized.
>>>>>>>>
>>>>>>>> I am running following commands:
>>>>>>>> clang  -S -emit-llvm sum-vec.c -march=knl -O3
-mllvm
>>>>>>>> -disable-llvm-optzns -o sum-vec.ll
>>>>>>>> opt  -S -O3 -force-vector-width=64 sum-vec.ll
-o sum-vec03.ll
>>>>>>>>
>>>>>>>> How to achieve this? Please help.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Thu, Aug 17, 2017 at 10:44 AM, Nemanja
Ivanovic <
>>>>>>>> nemanja.i.ibm at gmail.com> wrote:
>>>>>>>>
>>>>>>>>> I'm not sure what you expect to have
vectorized here. If you look
>>>>>>>>> at the emitted code, there's no loop.
It's just an add and a multiply as
>>>>>>>>> you might expect when adding a
loop-invariant sum 1000 times in a loop.
>>>>>>>>>
>>>>>>>>> On Wed, Aug 16, 2017 at 11:38 PM, hameeza
ahmed via llvm-dev <
>>>>>>>>> llvm-dev at lists.llvm.org> wrote:
>>>>>>>>>
>>>>>>>>>> Hello,
>>>>>>>>>> I have written the following code. when
i try to vectorize it
>>>>>>>>>> through opt. i am not getting
vectorized instructions.
>>>>>>>>>>
>>>>>>>>>> #include <stdio.h>
>>>>>>>>>> #include<stdlib.h>
>>>>>>>>>> int main(int argc, char** argv) {
>>>>>>>>>> int sum=0; int a=atoi(argv[1]); int
b=atoi(argv[2]);
>>>>>>>>>> for (int i=0;i<1000;i++)
>>>>>>>>>> {
>>>>>>>>>> sum+=a+b;
>>>>>>>>>> }
>>>>>>>>>>
>>>>>>>>>> printf("sum: %d\n", sum);
>>>>>>>>>> return 0;
>>>>>>>>>> }
>>>>>>>>>> i use following commands:
>>>>>>>>>> clang  -S -emit-llvm sum-main.c
-march=knl -O3 -mllvm
>>>>>>>>>> -disable-llvm-optzns -o sum-main.ll
>>>>>>>>>> opt  -S -O3 -force-vector-width=64
sum-main.ll -o sum-main03.ll
>>>>>>>>>>
>>>>>>>>>> why is that so? where am i doing
mistake? i am not getting
>>>>>>>>>> vectorized operations rather getting
scalar operations.
>>>>>>>>>>
>>>>>>>>>> Please help.
>>>>>>>>>>
>>>>>>>>>> Thank You
>>>>>>>>>>
>>>>>>>>>> Regards
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
_______________________________________________
>>>>>>>>>> LLVM Developers mailing list
>>>>>>>>>> llvm-dev at lists.llvm.org
>>>>>>>>>>
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
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