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fix: Exclude SM12x (desktop Blackwell) from CUDA_PTX_FP4FP6_CVT_ENABLED #3120

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fix: Exclude SM12x (desktop Blackwell) from CUDA_PTX_FP4FP6_CVT_ENABLED #3120

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12 changes: 8 additions & 4 deletions include/cutlass/float_subbyte.h
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Original file line number Diff line number Diff line change
Expand Up @@ -44,15 +44,19 @@
#define CUDA_FP4_ENABLED 1
#endif

// Note: SM12x (desktop Blackwell: RTX 5090/5080, DGX Spark GB10) is intentionally
// excluded below. SM12x GPUs have mma.e2m1 tensor cores but lack the
// cvt.rn.satfinite.e2m1x2.f32 PTX instruction required for native FP4/FP6
// conversion — this instruction is SM100-family only. Including SM12x here causes
// CUTLASS to emit invalid PTX, producing NaN during NVFP4 inference. SM12x falls
// through to the existing software E2M1 conversion path instead.
#if (defined(CUTLASS_ARCH_MMA_SM100A_ENABLED) || defined(CUTLASS_ARCH_MMA_SM101A_ENABLED) ||\
defined(CUTLASS_ARCH_MMA_SM103A_ENABLED) || defined(CUTLASS_ARCH_MMA_SM110A_ENABLED) ||\
defined(CUTLASS_ARCH_MMA_SM120A_ENABLED) || defined(CUTLASS_ARCH_MMA_SM121A_ENABLED))
defined(CUTLASS_ARCH_MMA_SM103A_ENABLED) || defined(CUTLASS_ARCH_MMA_SM110A_ENABLED))
# define CUDA_PTX_FP4FP6_CVT_ENABLED 1
#endif

#if (defined(CUTLASS_ARCH_MMA_SM100F_ENABLED) || defined(CUTLASS_ARCH_MMA_SM101F_ENABLED) ||\
defined(CUTLASS_ARCH_MMA_SM103F_ENABLED) || defined(CUTLASS_ARCH_MMA_SM110F_ENABLED) ||\
defined(CUTLASS_ARCH_MMA_SM120F_ENABLED) || defined(CUTLASS_ARCH_MMA_SM121F_ENABLED))
defined(CUTLASS_ARCH_MMA_SM103F_ENABLED) || defined(CUTLASS_ARCH_MMA_SM110F_ENABLED))
# define CUDA_PTX_FP4FP6_CVT_ENABLED 1
#endif

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