Mesa (master): r300/compiler: Don' t pair output writes with GPR writes in the scheduler

[Tom Stellard]

Module: Mesa
Branch: master
Commit: 51fe9994bdec1625a27e12216d492916e64ab622
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=51fe9994bdec1625a27e12216d492916e64ab622

Author: Tom Stellard <tstellar at gmail.com>
Date:   Thu Oct 13 16:32:35 2011 -0700

r300/compiler: Don't pair output writes with GPR writes in the scheduler

---

 .../drivers/r300/compiler/radeon_pair_schedule.c   |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/src/gallium/drivers/r300/compiler/radeon_pair_schedule.c b/src/gallium/drivers/r300/compiler/radeon_pair_schedule.c
index 1f589cd..ee868cc 100644
--- a/src/gallium/drivers/r300/compiler/radeon_pair_schedule.c
+++ b/src/gallium/drivers/r300/compiler/radeon_pair_schedule.c
@@ -511,6 +511,13 @@ static int merge_instructions(struct rc_pair_instruction * rgb, struct rc_pair_i
 		return 0;
 	}
 
+	/* Writing output registers in the middle of shaders is slow, so
+	 * we don't want to pair output writes with temp writes. */
+	if ((rgb->RGB.OutputWriteMask && !alpha->Alpha.OutputWriteMask)
+		|| (!rgb->RGB.OutputWriteMask && alpha->Alpha.OutputWriteMask)) {
+		return 0;
+	}
+
 	memcpy(&backup, rgb, sizeof(struct rc_pair_instruction));
 
 	if (destructive_merge_instructions(rgb, alpha))