diff options
| -rw-r--r-- | src/glsl/nir/nir_lower_vec_to_movs.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/src/glsl/nir/nir_lower_vec_to_movs.c b/src/glsl/nir/nir_lower_vec_to_movs.c index 287f2bf3d8b..c08b721dae4 100644 --- a/src/glsl/nir/nir_lower_vec_to_movs.c +++ b/src/glsl/nir/nir_lower_vec_to_movs.c @@ -83,7 +83,25 @@ insert_mov(nir_alu_instr *vec, unsigned start_idx, nir_shader *shader) } } - nir_instr_insert_before(&vec->instr, &mov->instr); + /* In some situations (if the vecN is involved in a phi-web), we can end + * up with a mov from a register to itself. Some of those channels may end + * up doing nothing and there's no reason to have them as part of the mov. + */ + if (src_matches_dest_reg(&mov->dest.dest, &mov->src[0].src) && + !mov->src[0].abs && !mov->src[0].negate) { + for (unsigned i = 0; i < 4; i++) { + if (mov->src[0].swizzle[i] == i) { + mov->dest.write_mask &= ~(1 << i); + } + } + } + + /* Only emit the instruction if it actually does something */ + if (mov->dest.write_mask) { + nir_instr_insert_before(&vec->instr, &mov->instr); + } else { + ralloc_free(mov); + } return mov->dest.write_mask; } |