freedreno/ir3: fix bit_count

Seems like it can only work 16b at a time.  Fixes
dEQP-GLES31.functional.shaders.builtin_functions.integer.bitcount.*

TODO need to check if this limitation applies to a3xx as well.

Signed-off-by: Rob Clark <robdclark@gmail.com>

diff --git a/src/freedreno/ir3/ir3_compiler_nir.c b/src/freedreno/ir3/ir3_compiler_nir.c
index 962dcdf1b884d1f5911f5992ae4a501b654eb177..b55f834920f137ac31e7f5cb4cd6fb143fba8642 100644 (file)
--- a/src/freedreno/ir3/ir3_compiler_nir.c
+++ b/src/freedreno/ir3/ir3_compiler_nir.c
@@ -616,9 +616,30 @@ emit_alu(struct ir3_context *ctx, nir_alu_instr *alu)
                dst[0] = ir3_SEL_B32(b, src[1], 0, cond, 0, src[2], 0);
                break;
        }
-       case nir_op_bit_count:
-               dst[0] = ir3_CBITS_B(b, src[0], 0);
+       case nir_op_bit_count: {
+               // TODO, we need to do this 16b at a time on a5xx+a6xx.. need to
+               // double check on earlier gen's.  Once half-precision support is
+               // in place, this should probably move to a NIR lowering pass:
+               struct ir3_instruction *hi, *lo;
+
+               hi = ir3_COV(b, ir3_SHR_B(b, src[0], 0, create_immed(b, 16), 0),
+                               TYPE_U32, TYPE_U16);
+               lo = ir3_COV(b, src[0], TYPE_U32, TYPE_U16);
+
+               hi = ir3_CBITS_B(b, hi, 0);
+               lo = ir3_CBITS_B(b, lo, 0);
+
+               // TODO maybe the builders should default to making dst half-precision
+               // if the src's were half precision, to make this less awkward.. otoh
+               // we should probably just do this lowering in NIR.
+               hi->regs[0]->flags |= IR3_REG_HALF;
+               lo->regs[0]->flags |= IR3_REG_HALF;
+
+               dst[0] = ir3_ADD_S(b, hi, 0, lo, 0);
+               dst[0]->regs[0]->flags |= IR3_REG_HALF;
+               dst[0] = ir3_COV(b, dst[0], TYPE_U16, TYPE_U32);
                break;
+       }
        case nir_op_ifind_msb: {
                struct ir3_instruction *cmp;
                dst[0] = ir3_CLZ_S(b, src[0], 0);