diff --git a/src/mesa/drivers/dri/i965/brw_vec4_reg_allocate.cpp b/src/mesa/drivers/dri/i965/brw_vec4_reg_allocate.cpp index 79fd15b12bb..2e5bc79b485 100644 --- a/src/mesa/drivers/dri/i965/brw_vec4_reg_allocate.cpp +++ b/src/mesa/drivers/dri/i965/brw_vec4_reg_allocate.cpp @@ -436,6 +436,18 @@ vec4_visitor::evaluate_spill_costs(float *spill_costs, bool *no_spill) if (type_sz(inst->dst.type) == 8 && inst->exec_size != 8) no_spill[inst->dst.nr] = true; + /* FROM_DOUBLE opcodes are setup so that they use a dst register + * with a size of 2 even if they only produce a single-precison + * result (this is so that the opcode can use the larger register to + * produce a 64-bit aligned intermediary result as required by the + * hardware during the conversion process). This creates a problem for + * spilling though, because when we attempt to emit a spill for the + * dst we see a 32-bit destination and emit a scratch write that + * allocates a single spill register. + */ + if (inst->opcode == VEC4_OPCODE_FROM_DOUBLE) + no_spill[inst->dst.nr] = true; + /* We can't spill registers that mix 32-bit and 64-bit access (that * contain 64-bit data that is operated on via 32-bit instructions) */