Forspoken (PPSA03984) has a pixel shader with
v_interp_p2_f16 v1, ..., v7 op_sel:[0,0,0,1], and main throws
"VOP3 interpolation modifiers are not implemented" one second after
start.
On GFX10, op_sel[3] of a 16-bit VOP3 result selects the high half of
the destination and keeps the other half. The decoder already maps
that bit to destination.sdwaSel 5 for the other 16-bit VOP3 ops, and
write16Bits/writeRawU32 then insert the result into bits 31:16 and
keep bits 15:0. v_interp_p2_f16 is the only 16-bit-result
interpolation instruction, so only it accepts the bit; other op_sel
bits and the bit on the 32-bit-result p1ll/p1lv forms are still
refused.
agc_vop3_interp_decode checks the decoded selector with and without
the bit, and that v_interp_p1ll_f16 still refuses it. In
agc_driver_interpolation_f16 the second v_interp_p2_f16 now writes the
high half of a register holding 0x00001234, and the GPU result must
keep 0x1234 in the low half.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Extend the decode test to mul:4, div:2, -|v2|, -|v2| div:2, a p2
coordinate with neg and a non-zero attribute channel, a clamped p2, and
the mov form with clamp and mul:2. All 18 accepted words are the
assembler output (llvm-mc -mcpu=gfx1010).
The assembler encodes the unused third source of the VOP3-encoded
interpolation forms as the inline constant 0 (src2 = 0x80, bit 25 of the
second word), which the decoder refused. Accept that encoding and refuse
any other third source. The decode test now uses the assembler words for
every accepted form and keeps the refusals one field away from a valid
word.
v_interp_p1_f32_e64, v_interp_p2_f32_e64 and v_interp_mov_f32_e64
(VOP3Interp opcodes 0x200, 0x201 and 0x202) reach the decoder as VOP3
and were refused as unimplemented VOP3 opcodes. Decode them into the
existing VInterpP1F32, VInterpP2F32 and VInterpMovF32 opcodes with the
VOP3Interp operand layout, so the interpolation translation already
used by the VINTRP encodings handles them.
Encodings and operand layout follow LLVM's gfx10 MC tests for
VOP3Interp_Real_gfx10 (D69348). The interpolation parameter is the low
six bits of src0, the channel bits 6:7, the coordinate (or the
interpolation parameter of the mov form) is src1, and clamp and omod
reach the destination. op_sel, the packed-half selector, a third source
and abs/neg on operands that do not exist throw.
