[LLVMdev] [NVPTX] PTXAS - Unimplemented feature: labels as initial values

[Dmitry N. Mikushin]

Hi Justin,

With attached patch we managed to fix the issue mentioned in this
thread. Maybe it needs additional cleanups, but is it applicable in
general, how do you think?

Thanks,
- D.

2012/7/18 Yuan Lin <yulin at nvidia.com>:
> In ptx, variables need to be defined before referenced. NVPTX emits the
> global variables in the order as in the LLVM IR and does not sort them. It
> is a bug in the NVPTX backend.
>
>
>
> Thanks.
>
>
>
> Yuan
>
>
>
>
>
> From: Dmitry N. Mikushin [mailto:maemarcus at gmail.com]
> Sent: Wednesday, July 18, 2012 7:44 AM
> To: LLVM-Dev
> Cc: Justin Holewinski; Yuan Lin
> Subject: [NVPTX] PTXAS - Unimplemented feature: labels as initial values
>
>
>
> Dear NVPTX community,
>
> PTXAS fails to compile the ptx code generated by NVPTX. Is it an issue of
> backend or an issue of PTXAS or a known reasonable restriction?
>
> Thanks,
> - Dima.
>
>> cat test.ll
> ; ModuleID = '__kernelgen_main_module'
> target datalayout = "e-p:64:64-i64:64:64-f64:64:64-n1:8:16:32:64"
> target triple = "ptx64-unknown-unknown"
>
> %struct.__st_parameter_dt.0.4 = type { %struct.__st_parameter_common.1.5,
> i64, i64*, i64*, i8*, i8*, i32, i32, i8*, i8*, i32, i32, i8*, [256 x i8],
> i32*, i64, i8*, i32, i32, i8*, i8*, i32, i32, i8*, i8*, i32, i32, i8*, i8*,
> i32, [4 x i8] }
> %struct.__st_parameter_common.1.5 = type { i32, i32, i8*, i32, i32, i8*,
> i32* }
> %"struct.kernelgen::kernel_t.2" = type opaque
> %struct.kernelgen_callback_data_t.3 = type opaque
>
> @.cst = hidden constant [11 x i8] c"reduce.f90\00", align 4096
> @z = unnamed_addr global i8* getelementptr inbounds ([3 x i8]* @.cst1, i64
> 0, i64 0), align 4096
> @.cst1 = hidden constant [3 x i8] c"zz\00", align 4096
> @a = unnamed_addr global i8* getelementptr inbounds ([3 x i8]* @.cst12, i64
> 0, i64 0), align 4096
> @.cst12 = hidden constant [3 x i8] c"aa\00", align 4096
> @.cst2 = hidden constant [26 x i8] c"Usage: %s <nx> <ny> <nz>\0A\00", align
> 4096
>
>> llc -march=nvptx64 test.ll -o test.ptx
>> cat test.ptx
> //
> // Generated by LLVM NVPTX Back-End
> //
>
> .version 3.0
> .target sm_10, texmode_independent
> .address_size 64
>
> .visible .global .align 4096 .b8 _2E_cst[11] = {114, 101, 100, 117, 99, 101,
> 46, 102, 57, 48, 0};
> .visible .global .align 4096 .u64 z = _2E_cst1;
> .visible .global .align 4096 .b8 _2E_cst1[3] = {122, 122, 0};
> .visible .global .align 4096 .u64 a = _2E_cst12;
> .visible .global .align 4096 .b8 _2E_cst12[3] = {97, 97, 0};
> .visible .global .align 4096 .b8 _2E_cst2[26] = {85, 115, 97, 103, 101, 58,
> 32, 37, 115, 32, 60, 110, 120, 62, 32, 60, 110, 121, 62, 32, 60, 110, 122,
> 62, 10, 0};
>
>> ptxas test.ptx -o test.cubin
> ptxas test.ptx, line 10; error   : Unimplemented feature: labels as initial
> values
> ptxas test.ptx, line 12; error   : Unimplemented feature: labels as initial
> values
> ptxas test.ptx, line 10; error   : Label expected for forward reference of
> '_2E_cst1'
> ptxas test.ptx, line 12; error   : Label expected for forward reference of
> '_2E_cst12'
> ptxas fatal   : Ptx assembly aborted due to errors
>
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