AVX512 miscompile during type legalization of v4f80

[ZviRackover]

Bugzilla Link	33349
Resolution	FIXED
Resolved on	Aug 10, 2017 10:37
Version	trunk
OS	Windows NT
Blocks	#33196
CC	@zmodem,@RKSimon

[ZviRackover]

target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

define void @​test(<4 x i1> %m, <4 x x86_fp80> %v, <8 x x86_fp80>%p) local_unnamed_addr {
bb:
%tmp = select <4 x i1> %m, <4 x x86_fp80> <x86_fp80 0xK3FFF8000000000000000, x86_fp80 0xK3FFF8000000000000000, x86_fp80 0xK3FFF8000000000000000, x86_fp80 0xK3FFF8000000000000000>, <4 x x86_fp80> zeroinitializer
%tmp43 = fadd <4 x x86_fp80> %v, %tmp
%tmp44 = shufflevector <4 x x86_fp80> %tmp43, <4 x x86_fp80> %v, <8 x i32> <i32 0, i32 4, i32 1, i32 5, i32 2, i32 6, i32 3, i32 7>
store <8 x x86_fp80> %tmp44, <8 x x86_fp80> %p, align 16
ret void
}

This isn't such a far-fetched case as it was minimized from a miscompile in the Eigen test-suite (test/matrix_power.cpp).

llc -mcpu=haswell does not crash.

llc -mcpu=skx hits an assertion:

llc: ../lib/CodeGen/SelectionDAG/LegalizeTypes.h:597: llvm::SDValue llvm::DAGTypeLegalizer::GetScalarizedVector(llvm::SDValue): Assertion `ScalarizedOp.getNode() && "Operand wasn't scalarized?"' failed.
#​0 0x00007f53f6db5aa9 llvm::sys::PrintStackTrace(llvm::raw_ostream&) /export/iusers/zrackove/llvm/build/../lib/Support/Unix/Signals.inc:398:11
#​1 0x00007f53f6db5c59 PrintStackTraceSignalHandler(void*) /export/iusers/zrackove/llvm/build/../lib/Support/Unix/Signals.inc:462:1
#​2 0x00007f53f6db42f3 llvm::sys::RunSignalHandlers() /users/zrackove/llvm/lib/Support/Signals.cpp:0:5
#​3 0x00007f53f6db5fb4 SignalHandler(int) /export/iusers/zrackove/llvm/build/../lib/Support/Unix/Signals.inc:252:1
#​4 0x00007f53f6354100 __restore_rt (/lib64/libpthread.so.0+0xf100)
#​5 0x00007f53f57965f7 __GI_raise /usr/src/debug/glibc-2.17-c758a686/signal/../nptl/sysdeps/unix/sysv/linux/raise.c:56:0
#​6 0x00007f53f5797ce8 __GI_abort /usr/src/debug/glibc-2.17-c758a686/stdlib/abort.c:92:0
#​7 0x00007f53f578f566 __assert_fail_base /usr/src/debug/glibc-2.17-c758a686/assert/assert.c:92:0
#​8 0x00007f53f578f612 (/lib64/libc.so.6+0x2e612)
#​9 0x00007f53f700f2b9 llvm::DAGTypeLegalizer::GetScalarizedVector(llvm::SDValue) /export/iusers/zrackove/llvm/build/../lib/CodeGen/SelectionDAG/LegalizeTypes.h:598:12
#​10 0x00007f53f70594fe llvm::DAGTypeLegalizer::ScalarizeVecRes_VSELECT(llvm::SDNode*) /users/zrackove/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp:305:18
#​11 0x00007f53f70584e6 llvm::DAGTypeLegalizer::ScalarizeVectorResult(llvm::SDNode*, unsigned int) /users/zrackove/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes. cpp:62:36
#​12 0x00007f53f703b2e7 llvm::DAGTypeLegalizer::run() /users/zrackove/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp:257:17
#​13 0x00007f53f7040bfe llvm::SelectionDAG::LegalizeTypes() /users/zrackove/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp:1173:34
#​14 0x00007f53f7194944 llvm::SelectionDAGISel::CodeGenAndEmitDAG() /users/zrackove/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:747:23
#​15 0x00007f53f7194042 llvm::SelectionDAGISel::SelectBasicBlock(llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::Instruction, true, false, void>, false, true>, llvm::ilist_iterator<llvm::ilist_detail::node_options<llvm::Instruction, true, false, void>, false, true>, bool&) /users/zrackove/llvm/lib/CodeGen/SelectionDAG/ SelectionDAGISel.cpp:654:1
#​16 0x00007f53f7193d5a llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) /users/zrackove/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:0:7
#​17 0x00007f53f719108e llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) /users/zrackove/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:460:22
#​18 0x00007f53f9f67afb (anonymous namespace)::X86DAGToDAGISel::runOnMachineFunction(llvm::MachineFunction&) /users/zrackove/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp: 177:25
#​19 0x00007f53f86dcd61 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) /users/zrackove/llvm/lib/CodeGen/MachineFunctionPass.cpp:62:8
#​20 0x00007f53f7f4b28f llvm::FPPassManager::runOnFunction(llvm::Function&) /users/zrackove/llvm/lib/IR/LegacyPassManager.cpp:1519:27
#​21 0x00007f53f7f4b5a5 llvm::FPPassManager::runOnModule(llvm::Module&) /users/zrackove/llvm/lib/IR/LegacyPassManager.cpp:1540:16
#​22 0x00007f53f7f4bd3a (anonymous namespace)::MPPassManager::runOnModule(llvm::Module&) /users/zrackove/llvm/lib/IR/LegacyPassManager.cpp:1596:27
#​23 0x00007f53f7f4b866 llvm::legacy::PassManagerImpl::run(llvm::Module&) /users/zrackove/llvm/lib/IR/LegacyPassManager.cpp:1699:16
#​24 0x00007f53f7f4c251 llvm::legacy::PassManager::run(llvm::Module&) /users/zrackove/llvm/lib/IR/LegacyPassManager.cpp:1730:3
#​25 0x00000000004213b4 compileModule(char**, llvm::LLVMContext&) /users/zrackove/llvm/tools/llc/llc.cpp:611:42

[zmodem]

Is this something that should be fixed for 5.0? Is it a regression?

[llvmbot]

It seems to pass on 4.0 so I guess its a regression. I'll try to upload a fix asap.

[llvmbot]

Uploaded a fix proposal: https://reviews.llvm.org/D36511

[zmodem]

It seems to pass on 4.0 so I guess its a regression. I'll try to upload a
fix asap.

Thanks! Let's track this as a blocker, then.

[llvmbot]

committed in r310552. (https://reviews.llvm.org/rL310552 )

[zmodem]

committed in r310552. (https://reviews.llvm.org/rL310552 )

Merged to 5.0 in r310635.

[zmodem]

mentioned in issue #33196

[llvmbot]

mentioned in issue llvm/llvm-bugzilla-archive#34177