[Mesa-dev] [PATCH] r600g: fix and optimize tgsi_cmp when using ABS and NEG modifier

[siro at das-labor.org]

From: Patrick Rudolph <siro at das-labor.org>

Some apps set NEG and ABS on the source param to test for zero.
Use ALU_OP3_CNDE insted of ALU_OP3_CNDGE and unset both modifiers.

It also removes the need for a MOV instruction, as ABS isn't
supported on op3.

Tested on AMD CAYMAN and AMD RV770.

Signed-off-by: Patrick Rudolph <siro at das-labor.org>
---
 src/gallium/drivers/r600/r600_shader.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/gallium/drivers/r600/r600_shader.c b/src/gallium/drivers/r600/r600_shader.c
index 77658f5..e5e2e3f 100644
--- a/src/gallium/drivers/r600/r600_shader.c
+++ b/src/gallium/drivers/r600/r600_shader.c
@@ -7707,6 +7707,15 @@ static int tgsi_cmp(struct r600_shader_ctx *ctx)
 	int i, r, j;
 	int lasti = tgsi_last_instruction(inst->Dst[0].Register.WriteMask);
 	int temp_regs[3];
+	unsigned op;
+
+	if (ctx->src[0].abs && ctx->src[0].neg) {
+		op = ALU_OP3_CNDE;
+		ctx->src[0].abs = 0;
+		ctx->src[0].neg = 0;
+	} else {
+		op = ALU_OP3_CNDGE;
+	}
 
 	for (j = 0; j < inst->Instruction.NumSrcRegs; j++) {
 		temp_regs[j] = 0;
@@ -7719,7 +7728,7 @@ static int tgsi_cmp(struct r600_shader_ctx *ctx)
 			continue;
 
 		memset(&alu, 0, sizeof(struct r600_bytecode_alu));
-		alu.op = ALU_OP3_CNDGE;
+		alu.op = op;
 		r = tgsi_make_src_for_op3(ctx, temp_regs[0], i, &alu.src[0], &ctx->src[0]);
 		if (r)
 			return r;
-- 
2.5.0