r600g: reorder LIT instructions to support src == dst

the attached patch should be an improvement over Vadim Girlin's patch
fixing LIT instruction for r600g (commit
2fe39b46e73aea37152777fe11d489e0b1bc3f92).

Instructions used in tgsi_lit have been reordered to always write to a
dst channel after the same channel in src has been read (so if src ==
dst, input values are not overwritten before being used).

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 36 insertions, 35 deletions

diff --git a/src/gallium/drivers/r600/r600_shader.c b/src/gallium/drivers/r600/r600_shader.c
index 02681081c93..86fdfbccbe9 100644
--- a/src/gallium/drivers/r600/r600_shader.c
+++ b/src/gallium/drivers/r600/r600_shader.c
@@ -1303,41 +1303,6 @@ static int tgsi_lit(struct r600_shader_ctx *ctx)
 	struct r600_bc_alu alu;
 	int r;
 
-	/* dst.x, <- 1.0  */
-	memset(&alu, 0, sizeof(struct r600_bc_alu));
-	alu.inst = CTX_INST(V_SQ_ALU_WORD1_OP2_SQ_OP2_INST_MOV);
-	alu.src[0].sel  = V_SQ_ALU_SRC_1; /*1.0*/
-	alu.src[0].chan = 0;
-	tgsi_dst(ctx, &inst->Dst[0], 0, &alu.dst);
-	alu.dst.write = (inst->Dst[0].Register.WriteMask >> 0) & 1;
-	r = r600_bc_add_alu(ctx->bc, &alu);
-	if (r)
-		return r;
-
-	/* dst.y = max(src.x, 0.0) */
-	memset(&alu, 0, sizeof(struct r600_bc_alu));
-	alu.inst = CTX_INST(V_SQ_ALU_WORD1_OP2_SQ_OP2_INST_MAX);
-	r600_bc_src(&alu.src[0], &ctx->src[0], 0);
-	alu.src[1].sel  = V_SQ_ALU_SRC_0; /*0.0*/
-	alu.src[1].chan = 0;
-	tgsi_dst(ctx, &inst->Dst[0], 1, &alu.dst);
-	alu.dst.write = (inst->Dst[0].Register.WriteMask >> 1) & 1;
-	r = r600_bc_add_alu(ctx->bc, &alu);
-	if (r)
-		return r;
-
-	/* dst.w, <- 1.0  */
-	memset(&alu, 0, sizeof(struct r600_bc_alu));
-	alu.inst = CTX_INST(V_SQ_ALU_WORD1_OP2_SQ_OP2_INST_MOV);
-	alu.src[0].sel  = V_SQ_ALU_SRC_1;
-	alu.src[0].chan = 0;
-	tgsi_dst(ctx, &inst->Dst[0], 3, &alu.dst);
-	alu.dst.write = (inst->Dst[0].Register.WriteMask >> 3) & 1;
-	alu.last = 1;
-	r = r600_bc_add_alu(ctx->bc, &alu);
-	if (r)
-		return r;
-
 	if (inst->Dst[0].Register.WriteMask & (1 << 2))
 	{
 		int chan;
@@ -1425,6 +1390,42 @@ static int tgsi_lit(struct r600_shader_ctx *ctx)
 				return r;
 		}
 	}
+
+	/* dst.y = max(src.x, 0.0) */
+	memset(&alu, 0, sizeof(struct r600_bc_alu));
+	alu.inst = CTX_INST(V_SQ_ALU_WORD1_OP2_SQ_OP2_INST_MAX);
+	r600_bc_src(&alu.src[0], &ctx->src[0], 0);
+	alu.src[1].sel  = V_SQ_ALU_SRC_0; /*0.0*/
+	alu.src[1].chan = 0;
+	tgsi_dst(ctx, &inst->Dst[0], 1, &alu.dst);
+	alu.dst.write = (inst->Dst[0].Register.WriteMask >> 1) & 1;
+	r = r600_bc_add_alu(ctx->bc, &alu);
+	if (r)
+		return r;
+
+	/* dst.x, <- 1.0  */
+	memset(&alu, 0, sizeof(struct r600_bc_alu));
+	alu.inst = CTX_INST(V_SQ_ALU_WORD1_OP2_SQ_OP2_INST_MOV);
+	alu.src[0].sel  = V_SQ_ALU_SRC_1; /*1.0*/
+	alu.src[0].chan = 0;
+	tgsi_dst(ctx, &inst->Dst[0], 0, &alu.dst);
+	alu.dst.write = (inst->Dst[0].Register.WriteMask >> 0) & 1;
+	r = r600_bc_add_alu(ctx->bc, &alu);
+	if (r)
+		return r;
+
+	/* dst.w, <- 1.0  */
+	memset(&alu, 0, sizeof(struct r600_bc_alu));
+	alu.inst = CTX_INST(V_SQ_ALU_WORD1_OP2_SQ_OP2_INST_MOV);
+	alu.src[0].sel  = V_SQ_ALU_SRC_1;
+	alu.src[0].chan = 0;
+	tgsi_dst(ctx, &inst->Dst[0], 3, &alu.dst);
+	alu.dst.write = (inst->Dst[0].Register.WriteMask >> 3) & 1;
+	alu.last = 1;
+	r = r600_bc_add_alu(ctx->bc, &alu);
+	if (r)
+		return r;
+
 	return 0;
 }