Module: Mesa Branch: main Commit: 2c427d7c20b88a7ee37448a8e871025b52833647 URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=2c427d7c20b88a7ee37448a8e871025b52833647
Author: Faith Ekstrand <[email protected]> Date: Tue Dec 5 20:45:56 2023 -0600 nak: Implement usub_sat Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26535> --- src/nouveau/compiler/nak.rs | 2 +- src/nouveau/compiler/nak_from_nir.rs | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 34 insertions(+), 1 deletion(-) diff --git a/src/nouveau/compiler/nak.rs b/src/nouveau/compiler/nak.rs index 929a4e40d5a..14780ef4925 100644 --- a/src/nouveau/compiler/nak.rs +++ b/src/nouveau/compiler/nak.rs @@ -127,7 +127,7 @@ fn nir_options(dev: &nv_device_info) -> nir_shader_compiler_options { op.lower_device_index_to_zero = true; op.lower_isign = true; op.lower_uadd_sat = dev.sm < 70; - op.lower_usub_sat = true; // TODO + op.lower_usub_sat = dev.sm < 70; op.lower_iadd_sat = true; // TODO op.use_interpolated_input_intrinsics = true; op.lower_int64_options = !(nir_lower_icmp64 diff --git a/src/nouveau/compiler/nak_from_nir.rs b/src/nouveau/compiler/nak_from_nir.rs index 01636c5211d..ccc8a08169b 100644 --- a/src/nouveau/compiler/nak_from_nir.rs +++ b/src/nouveau/compiler/nak_from_nir.rs @@ -1066,6 +1066,39 @@ impl<'a> ShaderFromNir<'a> { b.sel(ovf_lo.into(), u32::MAX.into(), sum_lo.into()) } } + nir_op_usub_sat => { + let x = srcs[0].as_ssa().unwrap(); + let y = srcs[1].as_ssa().unwrap(); + let sum_lo = b.alloc_ssa(RegFile::GPR, 1); + let ovf_lo = b.alloc_ssa(RegFile::Pred, 1); + // The result of OpIAdd3X is the 33-bit value + // + // s|o = x + !y + 1 + // + // The overflow bit of this result is true if and only if the + // subtract did NOT overflow. + b.push_op(OpIAdd3 { + dst: sum_lo.into(), + overflow: [ovf_lo.into(), Dst::None], + srcs: [0.into(), x[0].into(), Src::from(y[0]).ineg()], + }); + if alu.def.bit_size() == 64 { + let sum_hi = b.alloc_ssa(RegFile::GPR, 1); + let ovf_hi = b.alloc_ssa(RegFile::Pred, 1); + b.push_op(OpIAdd3X { + dst: sum_hi.into(), + overflow: [ovf_hi.into(), Dst::None], + srcs: [0.into(), x[1].into(), Src::from(y[1]).bnot()], + carry: [ovf_lo.into(), false.into()], + }); + let lo = b.sel(ovf_hi.into(), sum_lo.into(), 0.into()); + let hi = b.sel(ovf_hi.into(), sum_hi.into(), 0.into()); + [lo[0], hi[0]].into() + } else { + assert!(alu.def.bit_size() == 32); + b.sel(ovf_lo.into(), sum_lo.into(), 0.into()) + } + } nir_op_unpack_32_2x16_split_x => { b.prmt(srcs[0], 0.into(), [0, 1, 4, 4]) }
