r274110 - [AVX512] Zero extend cmp intrinsic return value.

Craig Topper via llvm-commits llvm-commits at lists.llvm.org
Mon Jul 4 23:39:06 PDT 2016


Unfortunately the policy is such that the current version of LLVM must be
able to read a bitcode or IR text file generated by any released version of
LLVM/clang from 3.0 till now. This is why the AutoUpgrade.cpp file exists
and it keeps growing and its only going to get worse.

Hopefully with the discussion about the version number for the release
after 3.9 we end up with a time based compatibility policy. This will allow
us to remove the auto upgrade code over time, but it will take many years
before we can remove auto upgrade being added now.

On Monday, July 4, 2016, Demikhovsky, Elena <elena.demikhovsky at intel.com>
wrote:

> I think that AVX-512 intrinsic handled in Clang should be removed from
> AutoUpgrade.
>
> If we decide to replace a call to llvm-backend intrinsic with generating
> LLVM IR directly from clang, we can remove llvm-backend intrinsic at all.
>
> Otherwise we’ll need to duplicate support in FE and BE for all AVX-512
> intrinsics.
>
>
>
> -          * Elena*
>
>
>
> *From:* Craig Topper [mailto:craig.topper at gmail.com
> <javascript:_e(%7B%7D,'cvml','craig.topper at gmail.com');>]
> *Sent:* Monday, July 04, 2016 21:53
> *To:* Breger, Igor <igor.breger at intel.com
> <javascript:_e(%7B%7D,'cvml','igor.breger at intel.com');>>
> *Cc:* Eric Christopher via cfe-commits <cfe-commits at lists.llvm.org
> <javascript:_e(%7B%7D,'cvml','cfe-commits at lists.llvm.org');>>;
> Demikhovsky, Elena <elena.demikhovsky at intel.com
> <javascript:_e(%7B%7D,'cvml','elena.demikhovsky at intel.com');>>
> *Subject:* Re: r274110 - [AVX512] Zero extend cmp intrinsic return value.
>
>
>
> We have to keep the autoupgrade code due to the requirement that we need
> to be able to load bitcode files from previous versions of llvm. Though the
> intrinsic autograde code is starting to become large.
>
>
> ~Craig
>
>
>
> On Mon, Jul 4, 2016 at 2:55 AM, Breger, Igor <igor.breger at intel.com
> <javascript:_e(%7B%7D,'cvml','igor.breger at intel.com');>> wrote:
>
> Thanks for working on this!
>
>
>
> Regards,
>
> Igor
>
>
>
> *From:* Craig Topper [mailto:craig.topper at gmail.com
> <javascript:_e(%7B%7D,'cvml','craig.topper at gmail.com');>]
> *Sent:* Monday, July 04, 2016 10:20
> *To:* Breger, Igor
> *Cc:* Eric Christopher via cfe-commits; Demikhovsky, Elena; Ouriel, Boaz
>
> *Subject:* Re: r274110 - [AVX512] Zero extend cmp intrinsic return value.
>
>
>
> I've modified the indices we use for the zero vector in r274484. This
> gives better codegen as it now looks like a concat to the backend. So now
> we just end up emitting unnecessary kshiftlw/kshiftrw pairs instead of
> converting to a wider vector op and back.
>
>
> ~Craig
>
>
>
> On Sun, Jul 3, 2016 at 1:32 PM, Craig Topper <craig.topper at gmail.com
> <javascript:_e(%7B%7D,'cvml','craig.topper at gmail.com');>> wrote:
>
> Also should we change the AutoUpgrade code for the cmp intrinsics in the
> backend to also use zero instead of undef?
>
>
> ~Craig
>
>
>
> On Sun, Jul 3, 2016 at 12:11 AM, Breger, Igor <igor.breger at intel.com
> <javascript:_e(%7B%7D,'cvml','igor.breger at intel.com');>> wrote:
>
> Hello Craig,
>
> Thanks a lot for pointing it out to me.  I familiar with this problem,  we
> are planning  to improve CodeGen to handle with this case in near future.
>
>
>
> Regards,
>
> Igor
>
>
>
> *From:* Craig Topper [mailto:craig.topper at gmail.com
> <javascript:_e(%7B%7D,'cvml','craig.topper at gmail.com');>]
> *Sent:* Saturday, July 02, 2016 08:46
> *To:* Breger, Igor; Eric Christopher via cfe-commits
> *Subject:* Re: r274110 - [AVX512] Zero extend cmp intrinsic return value.
>
>
>
> This change codgens to something really awful now. Can you take a look?
>
>
>
>             .section            __TEXT,__text,regular,pure_instructions
>
>             .section            __TEXT,__literal8,8byte_literals
>
>             .p2align           3
>
> LCPI0_0:
>
>             .quad   -1
>
>             .section            __TEXT,__const
>
>             .p2align           6
>
> LCPI0_1:
>
>             .quad   0
>
>             .quad   1
>
>             .quad   2
>
>             .quad   3
>
>             .quad   8
>
>             .quad   8
>
>             .quad   8
>
>             .quad   8
>
>             .section            __TEXT,__text,regular,pure_instructions
>
>             .globl   _test_mm_cmpeq_epu32_mask
>
>             .p2align           4, 0x90
>
> _test_mm_cmpeq_epu32_mask:
>
>             vpcmpeqd       %xmm1, %xmm0, %k1
>
>             vpbroadcastq   LCPI0_0(%rip), %zmm0 {%k1} {z}
>
>             vpxord %zmm1, %zmm1, %zmm1
>
>             vmovdqa64     LCPI0_1(%rip), %zmm2
>
>             vpermt2q         %zmm1, %zmm2, %zmm0
>
>             vpsllq   $63, %zmm0, %zmm0
>
>             vptestmq         %zmm0, %zmm0, %k0
>
>             kmovw            %k0, %eax
>
>             retq
>
>
> ~Craig
>
>
>
> On Wed, Jun 29, 2016 at 1:14 AM, Igor Breger via cfe-commits <
> cfe-commits at lists.llvm.org
> <javascript:_e(%7B%7D,'cvml','cfe-commits at lists.llvm.org');>> wrote:
>
> Author: ibreger
> Date: Wed Jun 29 03:14:17 2016
> New Revision: 274110
>
> URL: http://llvm.org/viewvc/llvm-project?rev=274110&view=rev
> Log:
> [AVX512]  Zero extend cmp intrinsic return value.
>
> Differential Revision: http://reviews.llvm.org/D21746
>
> Modified:
>     cfe/trunk/lib/CodeGen/CGBuiltin.cpp
>     cfe/trunk/test/CodeGen/avx512vl-builtins.c
>
> Modified: cfe/trunk/lib/CodeGen/CGBuiltin.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBuiltin.cpp?rev=274110&r1=274109&r2=274110&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGBuiltin.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGBuiltin.cpp Wed Jun 29 03:14:17 2016
> @@ -6460,8 +6460,8 @@ static Value *EmitX86MaskedCompare(CodeG
>        Indices[i] = i;
>      for (unsigned i = NumElts; i != 8; ++i)
>        Indices[i] = NumElts;
> -    Cmp = CGF.Builder.CreateShuffleVector(Cmp,
> UndefValue::get(Cmp->getType()),
> -                                          Indices);
> +    Cmp = CGF.Builder.CreateShuffleVector(
> +        Cmp, llvm::Constant::getNullValue(Cmp->getType()), Indices);
>    }
>    return CGF.Builder.CreateBitCast(Cmp,
>                                     IntegerType::get(CGF.getLLVMContext(),
>
> Modified: cfe/trunk/test/CodeGen/avx512vl-builtins.c
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/avx512vl-builtins.c?rev=274110&r1=274109&r2=274110&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/CodeGen/avx512vl-builtins.c (original)
> +++ cfe/trunk/test/CodeGen/avx512vl-builtins.c Wed Jun 29 03:14:17 2016
> @@ -8,6 +8,7 @@
>  __mmask8 test_mm_cmpeq_epu32_mask(__m128i __a, __m128i __b) {
>    // CHECK-LABEL: @test_mm_cmpeq_epu32_mask
>    // CHECK: icmp eq <4 x i32> %{{.*}}, %{{.*}}
> +  // CHECK: shufflevector <4 x i1> %{{.*}}, <4 x i1> zeroinitializer, <8
> x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 4, i32 4, i32 4>
>    return (__mmask8)_mm_cmpeq_epu32_mask(__a, __b);
>  }
>
>
>
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-- 
~Craig
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