Module: Mesa Branch: main Commit: 7d8bf7c167d962421d1f8af451b82188357926af URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=7d8bf7c167d962421d1f8af451b82188357926af
Author: Ian Romanick <[email protected]> Date: Wed Jul 28 18:16:24 2021 -0700 nir/lower_bit_size: Support add_sat and sub_sat Without this, lowered saturating ALU instructions would only clamp to the range of the new type instead of the range of the old type. v2: Use nir_iclamp. Suggested by Jason. Use new u_{int,uint}N_{min,max}() helpers. Fixes: 090e2824079 ("nir: Add a saturated unsigned integer add opcode") Reviewed-by: Jason Ekstrand <[email protected]> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12142> --- src/compiler/nir/nir_lower_bit_size.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/src/compiler/nir/nir_lower_bit_size.c b/src/compiler/nir/nir_lower_bit_size.c index e31d9c86000..0bfe723575f 100644 --- a/src/compiler/nir/nir_lower_bit_size.c +++ b/src/compiler/nir/nir_lower_bit_size.c @@ -81,6 +81,23 @@ lower_alu_instr(nir_builder *bld, nir_alu_instr *alu, unsigned bit_size) lowered_dst = nir_ishr_imm(bld, lowered_dst, dst_bit_size); } else { lowered_dst = nir_build_alu_src_arr(bld, op, srcs); + + /* The add_sat and sub_sat instructions need to clamp the result to the + * range of the original type. + */ + if (op == nir_op_iadd_sat || op == nir_op_isub_sat) { + const int64_t int_max = u_intN_max(dst_bit_size); + const int64_t int_min = u_intN_min(dst_bit_size); + + lowered_dst = nir_iclamp(bld, lowered_dst, + nir_imm_intN_t(bld, int_min, bit_size), + nir_imm_intN_t(bld, int_max, bit_size)); + } else if (op == nir_op_uadd_sat || op == nir_op_usub_sat) { + const uint64_t uint_max = u_uintN_max(dst_bit_size); + + lowered_dst = nir_umin(bld, lowered_dst, + nir_imm_intN_t(bld, uint_max, bit_size)); + } }
