Re: Clang collapses on template with 64 parameters

[Mark Geisert <mark at maxrnd dot com>]

Agner Fog wrote:
> Here's another bug report.
>
> Cygwin Clang fails when compiling a complicated program with big templates. The 
> same program compiles OK on Linux clang.
>
> I have not made a minimal test case because smaller cases compile ok.
>
> The test case is too big for attaching to a mailing list, so I have made it 
> available at:
>
> https://www.agner.org/rapporter/cygwin_clang_template_bug.zip
>
> Command line:
>
> clang  -m64 -std=c++17 -O2  -mfma -mavx512bw -mavx512dq -mavx512vl testbench2.cpp
>
> The compiler issues a long message:
>
> fatal error: error in backend: Cannot select: 0x6019f23c0: ch =
> store<ST64[%169](tbaa=<0x600f4af78>)(alias.scope=<0x601890348>,<0x6018c6ab8>)> 
> 0x601a239c8,
>        0x6019f2018, FrameIndex:i64<7>, undef:i64
>    0x6019f2018: v64i8,ch = VPSHUFBZrm<Mem:LD64[ConstantPool]> 0x6019dadb8, 
> 0x6019db438, TargetConstant:i8<1>, Register:i64 %noreg, TargetConstant:i32<0>, 
> Register:i32 %noreg, 0x601926528
>      0x6019dadb8: v64i8 = bitcast 0x6019f1c08
>        0x6019f1c08: v8i64 = VPBROADCASTQZr 0x6019db368
>          0x6019db368: v2i64 = extract_subvector 0x6019f1c08, Constant:i64<0>
>            0x6019f1c08: v8i64 = VPBROADCASTQZr 0x6019db368
>              0x6019db368: v2i64 = extract_subvector 0x6019f1c08, Constant:i64<0>
>                0x6019f1c08: v8i64 = VPBROADCASTQZr 0x6019db368
>                  0x6019db368: v2i64 = extract_subvector 0x6019f1c08, 
> Constant:i64<0>
>                    0x6019f1c08: v8i64 = VPBROADCASTQZr 0x6019db368
>
>                    0x601a23758: i64 = Constant<0>
>                0x601a23758: i64 = Constant<0>
>            0x601a23758: i64 = Constant<0>
>      0x6019db438: i64 = X86ISD::Wrapper TargetConstantPool:i64<<64 x i8> <i8 0, 
> i8 1, i8 2, i8 -128, i8 4, i8 5, i8 6, i8 -128, i8 -128, i8 -128, i8 -128, i8 
> -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 
> -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 
> -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 
> -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 
> -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 
> -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128>> 0
>        0x6019dbcc0: i64 = TargetConstantPool<<64 x i8> <i8 0, i8 1, i8 2, i8 
> -128, i8 4, i8 5, i8 6, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 
> -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 
> -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 
> -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 
> -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 
> -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 
> -128, i8 -128, i8 -128, i8 -128, i8 -128, i8 -128>> 0
>      0x6019db848: i8 = TargetConstant<1>
>      0x6019f1a68: i64 = Register %noreg
>      0x6019f20e8: i32 = TargetConstant<0>
>      0x601a23620: i32 = Register %noreg
>    0x6019dae20: i64 = FrameIndex<7>
>    0x6019f2288: i64 = undef
> In function: main
> clang-5.0: error: clang frontend command failed with exit code 70 (use -v to see 
> invocation)
> clang version 5.0.1 (tags/RELEASE_501/final)
> Target: x86_64-unknown-windows-cygnus
> Thread model: posix
> InstalledDir: /usr/bin
> clang-5.0: note: diagnostic msg: PLEASE submit a bug report to and include the 
> crash backtrace, preprocessed source, and associated run script.
> clang-5.0: note: diagnostic msg:
> ********************
>
> PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
> Preprocessed source(s) and associated run script(s) are located at:
> clang-5.0: note: diagnostic msg: /tmp/testbench2-31c6c0.cpp
> clang-5.0: note: diagnostic msg: /tmp/testbench2-31c6c0.sh
> clang-5.0: note: diagnostic msg:
>
> ********************
>
> The diagnostic files are included in the zip as diagnostic*

Just like your previous Clang bug report, this one, as detailed and complete as 
any developer could want :-), should also go to the Clang bugtracker at 
https://bugs.llvm.org.

..mark


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