[LLVMdev] TableGen patterns with multiple outputs

[Justin Holewinski]

Thanks for the info.  Is this on someone's list of things to do?


On Sun, Jan 6, 2013 at 7:41 PM, Bob Wilson <bob.wilson at apple.com> wrote:

>
> On Jan 4, 2013, at 9:52 AM, Justin Holewinski <justin.holewinski at gmail.com>
> wrote:
>
> Are multi-output patterns in TableGen supposed to work, or is that a known
> limitation in the current implementation?
>
>
> It is a known limitation.  You have to write C++ code to match patterns
> with multiple outputs.
>
>
> If I have TableGen code like the following...
>
> 1242 def SDTTestNode : SDTypeProfile<2, 1, [SDTCisSameAs<0, 1>]>;
> 1243 def TestNode : SDNode<"NVPTXISD::TestNode", SDTTestNode>;
> 1244
> 1245 def MyTestNode : NVPTXInst<(outs Int32Regs:$dst0, Int32Regs:$dst1),
> 1246                            (ins Int32Regs:$a),
> 1247                            "test $dst0, $dst1, $a;",
> 1248                            [(set Int32Regs:$dst0, Int32Regs:$dst1,
> (TestNode Int32Regs:$a))]>;
>
> ... TableGen crashes with the following stack trace:
>
> #0  0x00007fff8f372212 in __pthread_kill ()
> #1  0x00007fff8dc0eaf4 in pthread_kill ()
> #2  0x00000001003a978b in raise (sig=6) at Signals.inc:345
> #3  0x00000001003a9842 in abort () at Signals.inc:362
> #4  0x00000001003a9821 in __assert_rtn (func=0x1003d0d14 "operator[]",
> file=0x1003b169e
> "/Users/jholewinski/projects/llvm/src/llvm/include/llvm/ADT/SmallVector.h",
> line=139, expr=0x1003b16e7 "begin() + idx < end()") at Signals.inc:358
> #5  0x00000001000ca394 in
> llvm::SmallVectorTemplateCommon<llvm::EEVT::TypeSet, void>::operator[]
> (this=0x10384fed0, idx=1) at SmallVector.h:139
> #6  0x00000001000c965b in llvm::TreePatternNode::getExtType
> (this=0x10384fed0, ResNo=1) at CodeGenDAGPatterns.h:349
> #7  0x00000001000bd615 in llvm::CodeGenDAGPatterns::ParseInstructions
> (this=0x7fff5fbff0b0) at
> /Users/jholewinski/projects/llvm/src/llvm/utils/TableGen/CodeGenDAGPatterns.cpp:2782
> #8  0x00000001000b7143 in llvm::CodeGenDAGPatterns::CodeGenDAGPatterns
> (this=0x7fff5fbff0b0, R=@0x7fff5fbff670) at
> /Users/jholewinski/projects/llvm/src/llvm/utils/TableGen/CodeGenDAGPatterns.cpp:2077
> #9  0x00000001000b6a3d in llvm::CodeGenDAGPatterns::CodeGenDAGPatterns
> (this=0x7fff5fbff0b0, R=@0x7fff5fbff670) at
> /Users/jholewinski/projects/llvm/src/llvm/utils/TableGen/CodeGenDAGPatterns.cpp:2091
> #10 0x000000010024cd15 in InstrInfoEmitter (this=0x7fff5fbff0a8,
> R=@0x7fff5fbff670) at
> /Users/jholewinski/projects/llvm/src/llvm/utils/TableGen/InstrInfoEmitter.cpp:39
> #11 0x0000000100248e8d in InstrInfoEmitter (this=0x7fff5fbff0a8,
> R=@0x7fff5fbff670) at
> /Users/jholewinski/projects/llvm/src/llvm/utils/TableGen/InstrInfoEmitter.cpp:39
> #12 0x0000000100248e36 in llvm::EmitInstrInfo (RK=@0x7fff5fbff670,
> OS=@0x7fff5fbff518) at
> /Users/jholewinski/projects/llvm/src/llvm/utils/TableGen/InstrInfoEmitter.cpp:420
> #13 0x00000001002d0930 in LLVMTableGenMain (OS=@0x7fff5fbff518,
> Records=@0x7fff5fbff670) at
> /Users/jholewinski/projects/llvm/src/llvm/utils/TableGen/TableGen.cpp:106
> #14 0x00000001002e8385 in llvm::TableGenMain (argv0=0x7fff5fbffa88
> "/Users/jholewinski/projects/llvm/build/bin/llvm-tblgen",
> MainFn=0x1002d0880 <LLVMTableGenMain>) at
> /Users/jholewinski/projects/llvm/src/llvm/lib/TableGen/Main.cpp:117
> #15 0x00000001002d0864 in main (argc=11, argv=0x7fff5fbff8f8) at
> /Users/jholewinski/projects/llvm/src/llvm/utils/TableGen/TableGen.cpp:181
>
>
> The fault occurs in CodeGenDAGPatterns.cpp:
>
> 2781     for (unsigned i = 0; i != NumResults; ++i)
> 2782       ResultPattern->setType(i, Res0Node->getExtType(i));
>
> Res0Node has only 1 type, but it is expected to have 2.
>
>
> Looking at the X86 back-end code, it looks like there do exist
> multi-output instructions, but they all use physical (implicit) registers
> for the second destination, not arbitrary register types.  And if I change
> the second destination to be a certain physical register, this problem goes
> away in my code.  Is this just not a supported case currently?  Or am I
> doing something wrong?
>
> This is my first time looking into the TableGen internals, so I can't spot
> anything obviously wrong with the TableGen tool code.
>
> --
>
> Thanks,
>
> Justin Holewinski
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>
>


-- 

Thanks,

Justin Holewinski
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