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Jeff E via llvm-dev

2016-Jun-21 16:12 UTC

[llvm-dev] LLVM Backend Issues

Hi,

I am having issues running a new backend that I created for a new
architecture. I suspect these errors may have something to do with how I
have the string setup in LLVMTargetMachine() below?

Also - It would be great if someone could point me to a document that
describes some of these error messages? For example what does t26 ..t4 mean?

Thanks in advance for taking your valuable time to help me!

Jeff

jeff at ubuntu:~/code$ llc dft_gf_msp.ll
LLVM ERROR: Cannot select: t28: ch = store<ST2[%le](align=4), trunc to
i16>
t27, t26, FrameIndex:i32<14>, undef:i32
  t26: i32,ch = load<LD2[%sz](align=4), anyext from i16> t25,
FrameIndex:i32<2>, undef:i32
    t7: i32 = FrameIndex<2>
    t4: i32 = undef
  t17: i32 = FrameIndex<14>
  t4: i32 = undef
In function: main


LLVMTargetMachine(T, "e-m:e-p:32:32-i8:8:32-i16:16:32-n32-S32", TT,
CPU,
FS, Options, RM, CM, OL),
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Anton Korobeynikov via llvm-dev

2016-Jun-21 16:15 UTC

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[llvm-dev] LLVM Backend Issues

It seems you don't handle truncstores properly. So, you'd either need
to expand them, or lower / select properly.

t26, etc. is just a numbering of nodes in sdag, so you could easily
how the things are connected. It used to be just addresses in the past
instead :)

On Tue, Jun 21, 2016 at 7:12 PM, Jeff E via llvm-dev
<llvm-dev at lists.llvm.org> wrote:> Hi,
>
> I am having issues running a new backend that I created for a new
> architecture. I suspect these errors may have something to do with how I
> have the string setup in LLVMTargetMachine() below?
>
> Also - It would be great if someone could point me to a document that
> describes some of these error messages? For example what does t26 ..t4
mean?
>
> Thanks in advance for taking your valuable time to help me!
>
> Jeff
>
> jeff at ubuntu:~/code$ llc dft_gf_msp.ll
> LLVM ERROR: Cannot select: t28: ch = store<ST2[%le](align=4), trunc to
i16>
> t27, t26, FrameIndex:i32<14>, undef:i32
>   t26: i32,ch = load<LD2[%sz](align=4), anyext from i16> t25,
> FrameIndex:i32<2>, undef:i32
>     t7: i32 = FrameIndex<2>
>     t4: i32 = undef
>   t17: i32 = FrameIndex<14>
>   t4: i32 = undef
> In function: main
>
>
> LLVMTargetMachine(T, "e-m:e-p:32:32-i8:8:32-i16:16:32-n32-S32",
TT, CPU, FS,
> Options, RM, CM, OL),
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>


-- 
With best regards, Anton Korobeynikov
Department of Statistical Modelling, Saint Petersburg State University

Krzysztof Parzyszek via llvm-dev

2016-Jun-21 16:19 UTC

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[llvm-dev] LLVM Backend Issues

On 6/21/2016 11:12 AM, Jeff E via llvm-dev wrote:>
> Also - It would be great if someone could point me to a document that
> describes some of these error messages? For example what does t26 ..t4
mean?
The t.. are just identifiers of the DAG nodes. It used to print 
addresses, but they were long and would change every time.

The "cannot select" errors are not that hard to track down: compile
the
failing testcase with -debug-only=isel and you'll see all the steps 
being taken up to the moment of failure.  The last few messages will be 
something like "match failed at nnn".  In your build directory in 
lib/Target/<yourtarget> there will be a file
<yourtarget>GenDAGISel.inc.
  It contains the matching "script".  The numbers nnn are shown in 
comments in that file and correspond to the steps the matcher performs. 
You'll be able to see what exactly it's trying to match.

-Krzysztof

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, 
hosted by The Linux Foundation

Jeff E via llvm-dev

2016-Jun-22 18:25 UTC

head link

[llvm-dev] LLVM Backend Issues

Thanks Anton and Krzysztof!



Here is the dump using the -debug flag. At this point I am not making much
sense of this, would it be too much to ask if one of you could walk me
through one of these lines?

One thing that I didn't point out is that I never defined any separate
floating point registers, not sure if this will pose any issue?

Thanks again for your time!

Jeff

jeff at ubuntu:~/code$ llc -debug-only=isel dft_gf_msp.ll

=== main
Initial selection DAG: BB#0 'main:entry'
SelectionDAG has 18 nodes:
            t0: ch = EntryToken
          t4: ch = store<ST4[%retval]> t0, Constant:i32<0>,
FrameIndex:i32<0>, undef:i32
        t7: ch = store<ST4[%sz]> t4, Constant:i32<256>,
FrameIndex:i32<2>,
undef:i32
      t10: ch = store<ST4[%dir]> t7, ConstantFP:f32<-1.000000e+00>,
FrameIndex:i32<3>, undef:i32
    t12: ch = store<ST4[%m]> t10, Constant:i32<0>,
FrameIndex:i32<19>,
undef:i32
  t13: i32,ch = load<LD4[%sz]> t12, FrameIndex:i32<2>, undef:i32
    t15: ch = store<ST4[%j]> t13:1, t13, FrameIndex:i32<16>,
undef:i32
  t17: ch = store<ST4[%le]> t15, t13, FrameIndex:i32<14>, undef:i32


Optimized lowered selection DAG: BB#0 'main:entry'
SelectionDAG has 18 nodes:
            t0: ch = EntryToken
          t4: ch = store<ST4[%retval]> t0, Constant:i32<0>,
FrameIndex:i32<0>, undef:i32
        t7: ch = store<ST4[%sz]> t4, Constant:i32<256>,
FrameIndex:i32<2>,
undef:i32
      t19: ch = store<ST4[%dir]> t7, Constant:i32<-1082130432>,
FrameIndex:i32<3>, undef:i32
    t12: ch = store<ST4[%m]> t19, Constant:i32<0>,
FrameIndex:i32<19>,
undef:i32
  t13: i32,ch = load<LD4[%sz]> t12, FrameIndex:i32<2>, undef:i32
    t15: ch = store<ST4[%j]> t13:1, t13, FrameIndex:i32<16>,
undef:i32
  t17: ch = store<ST4[%le]> t15, t13, FrameIndex:i32<14>, undef:i32


Type-legalized selection DAG: BB#0 'main:entry'
SelectionDAG has 18 nodes:
            t0: ch = EntryToken
          t4: ch = store<ST4[%retval]> t0, Constant:i32<0>,
FrameIndex:i32<0>, undef:i32
        t7: ch = store<ST4[%sz]> t4, Constant:i32<256>,
FrameIndex:i32<2>,
undef:i32
      t19: ch = store<ST4[%dir]> t7, Constant:i32<-1082130432>,
FrameIndex:i32<3>, undef:i32
    t12: ch = store<ST4[%m]> t19, Constant:i32<0>,
FrameIndex:i32<19>,
undef:i32
  t13: i32,ch = load<LD4[%sz]> t12, FrameIndex:i32<2>, undef:i32
    t15: ch = store<ST4[%j]> t13:1, t13, FrameIndex:i32<16>,
undef:i32
  t17: ch = store<ST4[%le]> t15, t13, FrameIndex:i32<14>, undef:i32


Legalized selection DAG: BB#0 'main:entry'
SelectionDAG has 18 nodes:
            t0: ch = EntryToken
          t4: ch = store<ST4[%retval]> t0, Constant:i32<0>,
FrameIndex:i32<0>, undef:i32
        t7: ch = store<ST4[%sz]> t4, Constant:i32<256>,
FrameIndex:i32<2>,
undef:i32
      t19: ch = store<ST4[%dir]> t7, Constant:i32<-1082130432>,
FrameIndex:i32<3>, undef:i32
    t12: ch = store<ST4[%m]> t19, Constant:i32<0>,
FrameIndex:i32<19>,
undef:i32
  t13: i32,ch = load<LD4[%sz]> t12, FrameIndex:i32<2>, undef:i32
    t15: ch = store<ST4[%j]> t13:1, t13, FrameIndex:i32<16>,
undef:i32
  t17: ch = store<ST4[%le]> t15, t13, FrameIndex:i32<14>, undef:i32


Optimized legalized selection DAG: BB#0 'main:entry'
SelectionDAG has 18 nodes:
            t0: ch = EntryToken
          t4: ch = store<ST4[%retval]> t0, Constant:i32<0>,
FrameIndex:i32<0>, undef:i32
        t7: ch = store<ST4[%sz]> t4, Constant:i32<256>,
FrameIndex:i32<2>,
undef:i32
      t19: ch = store<ST4[%dir]> t7, Constant:i32<-1082130432>,
FrameIndex:i32<3>, undef:i32
    t12: ch = store<ST4[%m]> t19, Constant:i32<0>,
FrameIndex:i32<19>,
undef:i32
  t13: i32,ch = load<LD4[%sz]> t12, FrameIndex:i32<2>, undef:i32
    t15: ch = store<ST4[%j]> t13:1, t13, FrameIndex:i32<16>,
undef:i32
  t17: ch = store<ST4[%le]> t15, t13, FrameIndex:i32<14>, undef:i32


===== Instruction selection begins: BB#0 'entry'
ISEL: Starting pattern match on root node: t17: ch = store<ST4[%le]> t15,
t13, FrameIndex:i32<14>, undef:i32

  Match failed at index 0
LLVM ERROR: Cannot select: t17: ch = store<ST4[%le]> t15, t13,
FrameIndex:i32<14>, undef:i32
  t13: i32,ch = load<LD4[%sz]> t12, FrameIndex:i32<2>, undef:i32
    t6: i32 = FrameIndex<2>
    t3: i32 = undef
  t16: i32 = FrameIndex<14>
  t3: i32 = undef
In function: main



On Tue, Jun 21, 2016 at 11:19 AM, Krzysztof Parzyszek via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> On 6/21/2016 11:12 AM, Jeff E via llvm-dev wrote:
>
>>
>> Also - It would be great if someone could point me to a document that
>> describes some of these error messages? For example what does t26 ..t4
>> mean?
>>
>
> The t.. are just identifiers of the DAG nodes. It used to print addresses,
> but they were long and would change every time.
>
> The "cannot select" errors are not that hard to track down:
compile the
> failing testcase with -debug-only=isel and you'll see all the steps
being
> taken up to the moment of failure.  The last few messages will be something
> like "match failed at nnn".  In your build directory in
> lib/Target/<yourtarget> there will be a file
<yourtarget>GenDAGISel.inc.
> It contains the matching "script".  The numbers nnn are shown in
comments
> in that file and correspond to the steps the matcher performs. You'll
be
> able to see what exactly it's trying to match.
>
> -Krzysztof
>
>
> --
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted
> by The Linux Foundation
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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