Module: Mesa Branch: main Commit: 89f639c0ca4fea53f2f6715435c0451d4f9bd74b URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=89f639c0ca4fea53f2f6715435c0451d4f9bd74b
Author: Ian Romanick <[email protected]> Date: Mon Jan 25 16:31:44 2021 -0800 nir/algebraic: Remove spurious conversions from inside logic ops Not only does this eliminate a bunch of unnecessary type converting MOVs, but it can also enable some SWAR. The dEQP-VK.spirv_assembly.type.vec3.i8.bitwise_xor_frag test does something about like: c = a.x ^ b.x; d = a.y ^ b.y; e = a.z ^ b.z; After this change, it looks more like: uint t = i8vec3AsUint(a) ^ i8vec3AsUint(b); c = extract_u8(t, 0); d = extract_u8(t, 1); e = extract_u8(t, 2); On Ice Lake, this results in: SIMD8 shader: 41 instructions. 1 loops. 3804 cycles. 0:0 spills:fills, 5 sends SIMD8 shader: 31 instructions. 1 loops. 2844 cycles. 0:0 spills:fills, 5 sends Reviewed-by: Lionel Landwerlin <[email protected]> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9025> --- src/compiler/nir/nir_opt_algebraic.py | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/src/compiler/nir/nir_opt_algebraic.py b/src/compiler/nir/nir_opt_algebraic.py index 1bf08ee3214..264d49a4a7b 100644 --- a/src/compiler/nir/nir_opt_algebraic.py +++ b/src/compiler/nir/nir_opt_algebraic.py @@ -829,6 +829,33 @@ optimizations.extend([ (('i2f16', ('i2imp', 'a@32')), ('i2f16', a)), ]) +# Clean up junk left from 8-bit integer to 16-bit integer lowering. +optimizations.extend([ + # The u2u16(u2u8(X)) just masks off the upper 8-bits of X. This can be + # accomplished by mask the upper 8-bit of the immediate operand to the + # iand instruction. Often times, both patterns will end up being applied + # to the same original expression tree. + (('iand', ('u2u16', ('u2u8', 'a@16')), '#b'), ('iand', a, ('iand', b, 0xff))), + (('u2u16', ('u2u8(is_used_once)', ('iand', 'a@16', '#b'))), ('iand', a, ('iand', b, 0xff))), +]) + +for op in ['iand', 'ior', 'ixor']: + optimizations.extend([ + (('u2u8', (op, ('u2u16', ('u2u8', 'a@16')), ('u2u16', ('u2u8', 'b@16')))), ('u2u8', (op, a, b))), + (('u2u8', (op, ('u2u16', ('u2u8', 'a@32')), ('u2u16', ('u2u8', 'b@32')))), ('u2u8', (op, a, b))), + + # Undistribute extract from a logic op + ((op, ('extract_i8', a, '#b'), ('extract_i8', c, b)), ('extract_i8', (op, a, c), b)), + ((op, ('extract_u8', a, '#b'), ('extract_u8', c, b)), ('extract_u8', (op, a, c), b)), + ((op, ('extract_i16', a, '#b'), ('extract_i16', c, b)), ('extract_i16', (op, a, c), b)), + ((op, ('extract_u16', a, '#b'), ('extract_u16', c, b)), ('extract_u16', (op, a, c), b)), + + # Undistribute shifts from a logic op + ((op, ('ushr(is_used_once)', a, '#b'), ('ushr', c, b)), ('ushr', (op, a, c), b)), + ((op, ('ishr(is_used_once)', a, '#b'), ('ishr', c, b)), ('ishr', (op, a, c), b)), + ((op, ('ishl(is_used_once)', a, '#b'), ('ishl', c, b)), ('ishl', (op, a, c), b)), + ]) + # Integer sizes for s in [8, 16, 32, 64]: optimizations.extend([
