Mesa (master): freedreno/ir3: fix bit_count

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Module: Mesa
Branch: master
Commit: 2e01c534f4c7909dd2ca766bc0086b3355ccf321
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=2e01c534f4c7909dd2ca766bc0086b3355ccf321

Author: Rob Clark <robdclark at gmail.com>
Date:   Wed Mar 20 08:53:44 2019 -0400

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 at gmail.com>

---

 src/freedreno/ir3/ir3_compiler_nir.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/src/freedreno/ir3/ir3_compiler_nir.c b/src/freedreno/ir3/ir3_compiler_nir.c
index 962dcdf1b88..b55f834920f 100644
--- 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);