This is undefined behaviour in SPIR-V, but well-defined in DXBC, so we should explicitly 'and' the shift amount with 31.
Based on a vkd3d-proton patch by Philip Rebohle.
Signed-off-by: Conor McCarthy cmccarthy@codeweavers.com --- v2: Do not skip the operation for immediate constants. --- libs/vkd3d-shader/spirv.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/libs/vkd3d-shader/spirv.c b/libs/vkd3d-shader/spirv.c index fab92059..23668216 100644 --- a/libs/vkd3d-shader/spirv.c +++ b/libs/vkd3d-shader/spirv.c @@ -6846,6 +6846,18 @@ static void vkd3d_dxbc_compiler_emit_alu_instruction(struct vkd3d_dxbc_compiler for (i = 0; i < instruction->src_count; ++i) src_ids[i] = vkd3d_dxbc_compiler_emit_load_src(compiler, &src[i], dst->write_mask);
+ /* The SPIR-V specification states, "The resulting value is undefined if Shift is greater than or + * equal to the bit width of the components of Base." D3D applies only the lowest 5 bits of the shift. + * Microsoft fxc will compile immediate constants larger than 5 bits. Fixing up the constants would be + * more elegant, but the simplest way is to let this handle constants too. */ + if (instruction->handler_idx == VKD3DSIH_ISHL || instruction->handler_idx == VKD3DSIH_ISHR + || instruction->handler_idx == VKD3DSIH_USHR) + { + uint32_t mask_id = vkd3d_dxbc_compiler_get_constant_vector(compiler, VKD3D_SHADER_COMPONENT_UINT, + vkd3d_write_mask_component_count(dst->write_mask), 0x1f); + src_ids[1] = vkd3d_spirv_build_op_and(builder, type_id, src_ids[1], mask_id); + } + val_id = vkd3d_spirv_build_op_trv(builder, &builder->function_stream, op, type_id, src_ids, instruction->src_count); if (instruction->flags & VKD3DSI_PRECISE_XYZW)