Add PTXFDivFastPass to lower fdiv fast to NVPTX approximate division#800
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Add PTXFDivFastPass to lower fdiv fast to NVPTX approximate division#800vchuravy wants to merge 1 commit into
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The LLVM NVPTX backend handles fdiv fast for Float32 (→ div.approx.ftz.f32) but has no fast path for Float64. This IR-level pass covers both: - Float32: replaces fdiv with __nv_fast_fdividef (libdevice) - Float64: replaces fdiv with rcp.approx.ftz.d + Newton refinement, matching CUDA.jl's inv_fast(::Float64) algorithm The pass fires when the instruction carries the afn fast-math flag (set by @fastmath) or when target.fastmath=true. It follows the NVVMReflectPass pattern already in ptx.jl. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Overarching goal is to move the fast math handling from CUDA.jl to the GPUCompiler backend.
The LLVM NVPTX backend handles fdiv fast for Float32 (→ div.approx.ftz.f32)
but has no fast path for Float64. This IR-level pass covers both:
matching CUDA.jl's inv_fast(::Float64) algorithm
The pass fires when the instruction carries the afn fast-math flag (set by
@fastmath) or when target.fastmath=true. It follows the NVVMReflectPass
pattern already in ptx.jl.
Co-Authored-By: Claude Sonnet 4.6 noreply@anthropic.com