Mesa (master): r600g: Why all this fiddling with tgsi_helper_copy?

[Christian König]

Module: Mesa
Branch: master
Commit: 7be5455796facbe35cf1f1bdbefa83759b2e3b58
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=7be5455796facbe35cf1f1bdbefa83759b2e3b58

Author: Christian König <deathsimple at vodafone.de>
Date:   Sun Dec 12 15:13:39 2010 +0100

r600g: Why all this fiddling with tgsi_helper_copy?

tgsi_helper_copy is used on several occasions to copy a temporary result
into the real destination register to emulate writemasks for OP3 and
reduction operations. According to R600 ISA that's unnecessary.

This patch fixes this use for MAD, CMP and DP4.

---

 src/gallium/drivers/r600/r600_shader.c |   62 +++++++++++++++++++++-----------
 1 files changed, 41 insertions(+), 21 deletions(-)

diff --git a/src/gallium/drivers/r600/r600_shader.c b/src/gallium/drivers/r600/r600_shader.c
index a2fec20..268a633 100644
--- a/src/gallium/drivers/r600/r600_shader.c
+++ b/src/gallium/drivers/r600/r600_shader.c
@@ -1606,6 +1606,13 @@ static int tgsi_op3(struct r600_shader_ctx *ctx)
 	struct r600_bc_alu_src r600_src[3];
 	struct r600_bc_alu alu;
 	int i, j, r;
+	int lasti = 0;
+
+	for (i = 0; i < 4; i++) {
+		if (inst->Dst[0].Register.WriteMask & (1 << i)) {
+			lasti = i;
+		}
+	}
 
 	r = tgsi_split_constant(ctx, r600_src);
 	if (r)
@@ -1613,26 +1620,32 @@ static int tgsi_op3(struct r600_shader_ctx *ctx)
 	r = tgsi_split_literal_constant(ctx, r600_src);
 	if (r)
 		return r;
-	/* do it in 2 step as op3 doesn't support writemask */
-	for (i = 0; i < 4; i++) {
+	for (i = 0; i < lasti + 1; i++) {
+		if (!(inst->Dst[0].Register.WriteMask & (1 << i)))
+			continue;
+
 		memset(&alu, 0, sizeof(struct r600_bc_alu));
 		alu.inst = ctx->inst_info->r600_opcode;
 		for (j = 0; j < inst->Instruction.NumSrcRegs; j++) {
 			alu.src[j] = r600_src[j];
 			alu.src[j].chan = tgsi_chan(&inst->Src[j], i);
 		}
-		alu.dst.sel = ctx->temp_reg;
+
+		r = tgsi_dst(ctx, &inst->Dst[0], i, &alu.dst);
+		if (r)
+			return r;
+
 		alu.dst.chan = i;
 		alu.dst.write = 1;
 		alu.is_op3 = 1;
-		if (i == 3) {
+		if (i == lasti) {
 			alu.last = 1;
 		}
 		r = r600_bc_add_alu(ctx->bc, &alu);
 		if (r)
 			return r;
 	}
-	return tgsi_helper_copy(ctx, inst);
+	return 0;
 }
 
 static int tgsi_dp(struct r600_shader_ctx *ctx)
@@ -1655,7 +1668,13 @@ static int tgsi_dp(struct r600_shader_ctx *ctx)
 			alu.src[j] = r600_src[j];
 			alu.src[j].chan = tgsi_chan(&inst->Src[j], i);
 		}
-		alu.dst.sel = ctx->temp_reg;
+		if(inst->Dst[0].Register.WriteMask & (1 << i)) {
+			r = tgsi_dst(ctx, &inst->Dst[0], i, &alu.dst);
+			if (r)
+				return r;
+		} else {
+			alu.dst.sel = ctx->temp_reg;
+		}
 		alu.dst.chan = i;
 		alu.dst.write = 1;
 		/* handle some special cases */
@@ -1689,7 +1708,7 @@ static int tgsi_dp(struct r600_shader_ctx *ctx)
 		if (r)
 			return r;
 	}
-	return tgsi_helper_copy(ctx, inst);
+	return 0;
 }
 
 static int tgsi_tex(struct r600_shader_ctx *ctx)
@@ -2019,8 +2038,14 @@ static int tgsi_cmp(struct r600_shader_ctx *ctx)
 	struct tgsi_full_instruction *inst = &ctx->parse.FullToken.FullInstruction;
 	struct r600_bc_alu_src r600_src[3];
 	struct r600_bc_alu alu;
-	int use_temp = 0;
 	int i, r;
+	int lasti = 0;
+
+	for (i = 0; i < 4; i++) {
+		if (inst->Dst[0].Register.WriteMask & (1 << i)) {
+			lasti = i;
+		}
+	}
 
 	r = tgsi_split_constant(ctx, r600_src);
 	if (r)
@@ -2029,10 +2054,10 @@ static int tgsi_cmp(struct r600_shader_ctx *ctx)
 	if (r)
 		return r;
 
-	if (inst->Dst[0].Register.WriteMask != 0xf)
-		use_temp = 1;
+	for (i = 0; i < lasti + 1; i++) {
+		if (!(inst->Dst[0].Register.WriteMask & (1 << i)))
+			continue;
 
-	for (i = 0; i < 4; i++) {
 		memset(&alu, 0, sizeof(struct r600_bc_alu));
 		alu.inst = CTX_INST(V_SQ_ALU_WORD1_OP3_SQ_OP3_INST_CNDGE);
 		alu.src[0] = r600_src[0];
@@ -2044,24 +2069,19 @@ static int tgsi_cmp(struct r600_shader_ctx *ctx)
 		alu.src[2] = r600_src[1];
 		alu.src[2].chan = tgsi_chan(&inst->Src[1], i);
 
-		if (use_temp)
-			alu.dst.sel = ctx->temp_reg;
-		else {
-			r = tgsi_dst(ctx, &inst->Dst[0], i, &alu.dst);
-			if (r)
-				return r;
-		}
+		r = tgsi_dst(ctx, &inst->Dst[0], i, &alu.dst);
+		if (r)
+			return r;
+
 		alu.dst.chan = i;
 		alu.dst.write = 1;
 		alu.is_op3 = 1;
-		if (i == 3)
+		if (i == lasti)
 			alu.last = 1;
 		r = r600_bc_add_alu(ctx->bc, &alu);
 		if (r)
 			return r;
 	}
-	if (use_temp)
-		return tgsi_helper_copy(ctx, inst);
 	return 0;
 }