[llvm-dev] [EXTERNAL] Re: ORC JIT error when using AVX2 vector instructions
Frank Winter via llvm-dev
llvm-dev at lists.llvm.org
Mon Aug 30 15:57:59 PDT 2021
Hi Stefan.
Thanks for the tip. But, it didn't do the trick - still only SSE. (the /proc/cpuinfo contains flag 'avx2')
I instrumented a bit:
JITTargetMachineBuilder JTMB((*TPC)->getTargetTriple());
llvm::outs() << "feature string: " << JTMB.getFeatures().getString() << "\n";
llvm::outs() << "adding features...\n";
JTMB.addFeatures({"+avx2"});
llvm::outs() << "feature string: " << JTMB.getFeatures().getString() << "\n";
Output:
Creating JIT
feature string:
adding features...
feature string: +avx2
Creating JIT successfu
But still only SSE:
.Leval0_intern:
.cfi_startproc
addl %esi, %edi
shll $3, %edi
movslq %edi, %rax
shlq $5, %rax
movaps (%r8,%rax), %xmm0
movaps 16(%r8,%rax), %xmm1
mulps 16(%rcx,%rax), %xmm1
mulps (%rcx,%rax), %xmm0
movaps %xmm0, (%rdx,%rax)
movaps %xmm1, 16(%rdx,%rax)
retq
Should I switch to LLVM 13 release or is avx2 in JIT a trusted feature to be present in version 12?
Best,
Frank
________________________________
From: Stefan Gränitz <stefan.graenitz at gmail.com>
Sent: Monday, August 30, 2021 5:00 PM
To: Frank Winter <fwinter at jlab.org>; Craig Topper <craig.topper at gmail.com>
Cc: llvm-dev at lists.llvm.org <llvm-dev at lists.llvm.org>
Subject: Re: [llvm-dev] [EXTERNAL] Re: ORC JIT error when using AVX2 vector instructions
Hi Frank
That makes me think that the ORC JIT Kaleidoscope doesn't use the '+avx2' attribute.
How can ORC JIT Kaleidoscope generate jitted code with AVX2 instructions?
Did you try adding something like:
JTMB.addFeatures({"+avx2"});
Here?
https://github.com/llvm/llvm-project/blob/7a2a765745973ebeb041276d2d9489a000ba9371/llvm/examples/Kaleidoscope/BuildingAJIT/Chapter1/KaleidoscopeJIT.h#L71<https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_llvm_llvm-2Dproject_blob_7a2a765745973ebeb041276d2d9489a000ba9371_llvm_examples_Kaleidoscope_BuildingAJIT_Chapter1_KaleidoscopeJIT.h-23L71&d=DwMD-g&c=CJqEzB1piLOyyvZjb8YUQw&r=tFpAzszScTWMAFcrGFW5xg&m=d7g1B6MAn9hV6ijrMKBgXHMYCQjKMfXQcxFZUzXsIIE&s=1xpxLmfuaVlN3_P_Uw-FHKkrxSRG2uXXxT44bMGkOWA&e=>
Hope it helps.
Best, Stefan
On 30/08/2021 21:46, Frank Winter via llvm-dev wrote:
Thanks! Yeah, that was my silliness. Fixed and the module compiles now with ORC JIT Kaleidoscope.
However, looking at the assembler I only see SSE (128 bit vectors) being generated:
.Leval0_intern:
.cfi_startproc
addl %esi, %edi
shll $3, %edi
movslq %edi, %rax
shlq $5, %rax
movaps (%r8,%rax), %xmm0
movaps 16(%r8,%rax), %xmm1
mulps 16(%rcx,%rax), %xmm1
mulps (%rcx,%rax), %xmm0
movaps %xmm0, (%rdx,%rax)
movaps %xmm1, 16(%rdx,%rax)
retq
I cross checked what LLC gives:
Calling llc with no optional flags gives matching assembler, but when adding '-mattr=+avx2' I get AVX2 (256 bit vectors)
.Leval0_intern: # @eval0_intern
.cfi_startproc
# %bb.0: # %stack
addl %esi, %edi
shll $3, %edi
movslq %edi, %rax
shlq $5, %rax
vmovaps (%r8,%rax), %ymm0
vmulps (%rcx,%rax), %ymm0, %ymm0
vmovaps %ymm0, (%rdx,%rax)
vzeroupper
retq
That makes me think that the ORC JIT Kaleidoscope doesn't use the '+avx2' attribute.
How can ORC JIT Kaleidoscope generate jitted code with AVX2 instructions?
Thanks again & Best wishes,
Frank
________________________________
From: Craig Topper <craig.topper at gmail.com><mailto:craig.topper at gmail.com>
Sent: Monday, August 30, 2021 3:20 PM
To: Frank Winter <fwinter at jlab.org><mailto:fwinter at jlab.org>
Cc: llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org> <llvm-dev at lists.llvm.org><mailto:llvm-dev at lists.llvm.org>
Subject: [EXTERNAL] Re: [llvm-dev] ORC JIT error when using AVX2 vector instructions
This is an illegal instruction. mul is an integer operation, but that has floating point types. The correct operation would be fmul.
%21 = mul <8 x float> %20, %10
~Craig
On Mon, Aug 30, 2021 at 12:08 PM Frank Winter via llvm-dev <llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:
Hi.
As soon as the module contains instructions operating on < 8 x float > the ORC JIT refuses to work.
Here's the module that provokes the error given further below:
; ModuleID = 'module'
source_filename = "module"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
define private void @eval0_intern(i32 %arg0, i32 %arg1, <8 x float>* %arg2, <8 x float>* %arg3, <8 x float>* %arg4) {
stack:
br label %afterstack
afterstack: ; preds = %stack
%0 = add nsw i32 %arg0, %arg1
%1 = add nsw i32 0, %0
%2 = mul i32 %1, 1
%3 = add nsw i32 %2, 0
%4 = mul i32 %3, 1
%5 = add nsw i32 %4, 0
%6 = mul i32 %5, 1
%7 = add nsw i32 %6, 0
%8 = mul i32 %7, 8
%9 = getelementptr <8 x float>, <8 x float>* %arg3, i32 %8
%10 = load <8 x float>, <8 x float>* %9, align 32
%11 = add nsw i32 0, %0
%12 = mul i32 %11, 1
%13 = add nsw i32 %12, 0
%14 = mul i32 %13, 1
%15 = add nsw i32 %14, 0
%16 = mul i32 %15, 1
%17 = add nsw i32 %16, 0
%18 = mul i32 %17, 8
%19 = getelementptr <8 x float>, <8 x float>* %arg4, i32 %18
%20 = load <8 x float>, <8 x float>* %19, align 32
%21 = mul <8 x float> %20, %10
%22 = add nsw i32 0, %0
%23 = mul i32 %22, 1
%24 = add nsw i32 %23, 0
%25 = mul i32 %24, 1
%26 = add nsw i32 %25, 0
%27 = mul i32 %26, 1
%28 = add nsw i32 %27, 0
%29 = mul i32 %28, 8
%30 = getelementptr <8 x float>, <8 x float>* %arg2, i32 %29
store <8 x float> %21, <8 x float>* %30, align 32
ret void
}
define void @eval0(i32 %idx, [8 x i8]* %arg_ptr) {
entrypoint:
%0 = getelementptr [8 x i8], [8 x i8]* %arg_ptr, i32 0
%1 = bitcast [8 x i8]* %0 to i32*
%2 = load i32, i32* %1, align 4
%3 = getelementptr [8 x i8], [8 x i8]* %arg_ptr, i32 1
%4 = bitcast [8 x i8]* %3 to <8 x float>**
%5 = load <8 x float>*, <8 x float>** %4, align 8
%6 = getelementptr [8 x i8], [8 x i8]* %arg_ptr, i32 2
%7 = bitcast [8 x i8]* %6 to <8 x float>**
%8 = load <8 x float>*, <8 x float>** %7, align 8
%9 = getelementptr [8 x i8], [8 x i8]* %arg_ptr, i32 3
%10 = bitcast [8 x i8]* %9 to <8 x float>**
%11 = load <8 x float>*, <8 x float>** %10, align 8
call void @eval0_intern(i32 %idx, i32 %2, <8 x float>* %5, <8 x float>* %8, <8 x float>* %11)
ret void
}
--------------------------
For the JIT part I'm using the Kaleidoscope ORC JIT as given in the LLVM examples. However, when it comes to the symbol lookup the program stops with output like this:
Lookup
LLVM ERROR: Cannot select: 0x562e8bb6c268: v4f32 = mul 0x562e8bb6bab0, 0x562e8bb6b6a0
0x562e8bb6bab0: v4f32,ch = load<(load 16 from %ir.19 + 16, basealign 32)> 0x562e8baf8ca8, 0x562e8bb6c130, undef:i64
0x562e8bb6c130: i64 = add nuw 0x562e8bb6bcb8, Constant:i64<16>
0x562e8bb6bcb8: i64 = add 0x562e8bb6bc50, 0x562e8bb6b9e0
0x562e8bb6bc50: i64,ch = CopyFromReg 0x562e8baf8ca8, Register:i64 %4
0x562e8bb6bbe8: i64 = Register %4
0x562e8bb6b9e0: i64 = shl 0x562e8bb6b910, Constant:i8<5>
0x562e8bb6b910: i64 = sign_extend 0x562e8bb6b770
0x562e8bb6b770: i32 = shl 0x562e8bb6b500, Constant:i8<3>
0x562e8bb6b500: i32 = add nsw 0x562e8bb6b3c8, 0x562e8bb6b498
0x562e8bb6b3c8: i32,ch = CopyFromReg 0x562e8baf8ca8, Register:i32 %0
0x562e8bb6b360: i32 = Register %0
0x562e8bb6b498: i32,ch = CopyFromReg 0x562e8baf8ca8, Register:i32 %1
0x562e8bb6b430: i32 = Register %1
0x562e8bb6ea28: i8 = Constant<3>
0x562e8bb6c2d0: i8 = Constant<5>
0x562e8bb6b638: i64 = Constant<16>
0x562e8bb6bb18: i64 = undef
0x562e8bb6b6a0: v4f32,ch = load<(load 16 from %ir.9 + 16, basealign 32)> 0x562e8baf8ca8, 0x562e8bb6c198, undef:i64
0x562e8bb6c198: i64 = add nuw 0x562e8bb6ba48, Constant:i64<16>
0x562e8bb6ba48: i64 = add 0x562e8bb6b8a8, 0x562e8bb6b9e0
0x562e8bb6b8a8: i64,ch = CopyFromReg 0x562e8baf8ca8, Register:i64 %3
0x562e8bb6b840: i64 = Register %3
0x562e8bb6b9e0: i64 = shl 0x562e8bb6b910, Constant:i8<5>
0x562e8bb6b910: i64 = sign_extend 0x562e8bb6b770
0x562e8bb6b770: i32 = shl 0x562e8bb6b500, Constant:i8<3>
0x562e8bb6b500: i32 = add nsw 0x562e8bb6b3c8, 0x562e8bb6b498
0x562e8bb6b3c8: i32,ch = CopyFromReg 0x562e8baf8ca8, Register:i32 %0
0x562e8bb6b360: i32 = Register %0
0x562e8bb6b498: i32,ch = CopyFromReg 0x562e8baf8ca8, Register:i32 %1
0x562e8bb6b430: i32 = Register %1
0x562e8bb6ea28: i8 = Constant<3>
0x562e8bb6c2d0: i8 = Constant<5>
0x562e8bb6b638: i64 = Constant<16>
0x562e8bb6bb18: i64 = undef
The module compiles fine with LLC. So, I assume that's not the problem.
What might go wrong? Is there a way to initialize the ORC JIT with the AVX2 option somehow?
This is using LLVM release 12.
Best,
Frank
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