[Mesa-dev] [PATCH 3/4] r600: clean up fragment shader input scan code

[sroland at vmware.com]

From: Roland Scheidegger <sroland at vmware.com>

For some reason, we were iterating through the code twice (first just for
instructions needing barycentrics, then for instructions and input dcls).
Move things around slightly so this is no longer necessary.
There also was a unnedeed enabling of the fixed_pt_position_gpr - this is only
needed if the per-sample interpolation comes from an input, not from an
instruction (just move the assert where it belongs) (since the sample id to
sample from comes from a tgsi src in this case, and isn't sampleID).
Otherwise there should be no functional change.
---
 src/gallium/drivers/r600/r600_shader.c | 75 +++++++++++-----------------------
 1 file changed, 23 insertions(+), 52 deletions(-)

diff --git a/src/gallium/drivers/r600/r600_shader.c b/src/gallium/drivers/r600/r600_shader.c
index 13aa681049..1009411c62 100644
--- a/src/gallium/drivers/r600/r600_shader.c
+++ b/src/gallium/drivers/r600/r600_shader.c
@@ -1111,7 +1111,6 @@ static int allocate_system_value_inputs(struct r600_shader_ctx *ctx, int gpr_off
 
 				if (inst->Instruction.Opcode == TGSI_OPCODE_INTERP_SAMPLE) {
 					location = TGSI_INTERPOLATE_LOC_CENTER;
-					inputs[1].enabled = true; /* needs SAMPLEID */
 				} else if (inst->Instruction.Opcode == TGSI_OPCODE_INTERP_OFFSET) {
 					location = TGSI_INTERPOLATE_LOC_CENTER;
 					/* Needs sample positions, currently those are always available */
@@ -1139,6 +1138,19 @@ static int allocate_system_value_inputs(struct r600_shader_ctx *ctx, int gpr_off
 
 	tgsi_parse_free(&parse);
 
+	if (ctx->bc->chip_class >= EVERGREEN) {
+		int num_baryc = 0;
+		/* assign gpr to each interpolator according to priority */
+		for (i = 0; i < ARRAY_SIZE(ctx->eg_interpolators); i++) {
+			if (ctx->eg_interpolators[i].enabled) {
+				ctx->eg_interpolators[i].ij_index = num_baryc;
+				num_baryc++;
+			}
+		}
+		num_baryc = (num_baryc + 1) >> 1;
+		gpr_offset += num_baryc;
+	}
+
 	for (i = 0; i < ARRAY_SIZE(inputs); i++) {
 		boolean enabled = inputs[i].enabled;
 		int *reg = inputs[i].reg;
@@ -1165,18 +1177,21 @@ static int allocate_system_value_inputs(struct r600_shader_ctx *ctx, int gpr_off
  * for evergreen we need to scan the shader to find the number of GPRs we need to
  * reserve for interpolation and system values
  *
- * we need to know if we are going to emit
- * any sample or centroid inputs
+ * we need to know if we are going to emit any sample or centroid inputs
  * if perspective and linear are required
 */
 static int evergreen_gpr_count(struct r600_shader_ctx *ctx)
 {
 	unsigned i;
-	int num_baryc;
-	struct tgsi_parse_context parse;
 
 	memset(&ctx->eg_interpolators, 0, sizeof(ctx->eg_interpolators));
 
+	/*
+	 * Could get this information from the shader info. But right now
+	 * we interpolate all declared inputs, whereas the shader info will
+	 * only contain the bits if the inputs are actually used, so it might
+	 * not be safe...
+	 */
 	for (i = 0; i < ctx->info.num_inputs; i++) {
 		int k;
 		/* skip position/face/mask/sampleid */
@@ -1193,53 +1208,9 @@ static int evergreen_gpr_count(struct r600_shader_ctx *ctx)
 			ctx->eg_interpolators[k].enabled = TRUE;
 	}
 
-	if (tgsi_parse_init(&parse, ctx->tokens) != TGSI_PARSE_OK) {
-		return 0;
-	}
-
-	/* need to scan shader for system values and interpolateAtSample/Offset/Centroid */
-	while (!tgsi_parse_end_of_tokens(&parse)) {
-		tgsi_parse_token(&parse);
-
-		if (parse.FullToken.Token.Type == TGSI_TOKEN_TYPE_INSTRUCTION) {
-			const struct tgsi_full_instruction *inst = &parse.FullToken.FullInstruction;
-			if (inst->Instruction.Opcode == TGSI_OPCODE_INTERP_SAMPLE ||
-				inst->Instruction.Opcode == TGSI_OPCODE_INTERP_OFFSET ||
-				inst->Instruction.Opcode == TGSI_OPCODE_INTERP_CENTROID)
-			{
-				int interpolate, location, k;
-
-				if (inst->Instruction.Opcode == TGSI_OPCODE_INTERP_SAMPLE) {
-					location = TGSI_INTERPOLATE_LOC_CENTER;
-				} else if (inst->Instruction.Opcode == TGSI_OPCODE_INTERP_OFFSET) {
-					location = TGSI_INTERPOLATE_LOC_CENTER;
-				} else {
-					location = TGSI_INTERPOLATE_LOC_CENTROID;
-				}
-
-				interpolate = ctx->info.input_interpolate[inst->Src[0].Register.Index];
-				k = eg_get_interpolator_index(interpolate, location);
-				if (k >= 0)
-					ctx->eg_interpolators[k].enabled = true;
-			}
-		}
-	}
-
-	tgsi_parse_free(&parse);
-
-	/* assign gpr to each interpolator according to priority */
-	num_baryc = 0;
-	for (i = 0; i < ARRAY_SIZE(ctx->eg_interpolators); i++) {
-		if (ctx->eg_interpolators[i].enabled) {
-			ctx->eg_interpolators[i].ij_index = num_baryc;
-			num_baryc ++;
-		}
-	}
-
 	/* XXX PULL MODEL and LINE STIPPLE */
 
-	num_baryc = (num_baryc + 1) >> 1;
-	return allocate_system_value_inputs(ctx, num_baryc);
+	return allocate_system_value_inputs(ctx, 0);
 }
 
 /* sample_id_sel == NULL means fetch for current sample */
@@ -1248,8 +1219,6 @@ static int load_sample_position(struct r600_shader_ctx *ctx, struct r600_shader_
 	struct r600_bytecode_vtx vtx;
 	int r, t1;
 
-	assert(ctx->fixed_pt_position_gpr != -1);
-
 	t1 = r600_get_temp(ctx);
 
 	memset(&vtx, 0, sizeof(struct r600_bytecode_vtx));
@@ -1257,6 +1226,8 @@ static int load_sample_position(struct r600_shader_ctx *ctx, struct r600_shader_
 	vtx.buffer_id = R600_BUFFER_INFO_CONST_BUFFER;
 	vtx.fetch_type = SQ_VTX_FETCH_NO_INDEX_OFFSET;
 	if (sample_id == NULL) {
+		assert(ctx->fixed_pt_position_gpr != -1);
+
 		vtx.src_gpr = ctx->fixed_pt_position_gpr; // SAMPLEID is in .w;
 		vtx.src_sel_x = 3;
 	}
-- 
2.12.3