[Mesa-dev] [PATCH 2/2] mesa/program: Don't copy propagate from swizzles.

[Fabian Bieler]

Do not propagate a copy if source and destination are identical.

Otherwise code like

MOV TEMP[0].xyzw, TEMP[0].wzyx
MOV TEMP[1].xyzw, TEMP[0].xyzw

is changed to

MOV TEMP[0].xyzw, TEMP[0].wzyx
MOV TEMP[1].xyzw, TEMP[0].wzyx

This fixes Piglit test shaders/glsl-copy-propagation-self-2 for drivers that
use Mesa IR.

NOTE: This is a candidate for the stable branches.
Signed-off-by: Fabian Bieler <fabianbieler at fastmail.fm>
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
---
 src/mesa/program/ir_to_mesa.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp
index 14cf5ba..dff1762 100644
--- a/src/mesa/program/ir_to_mesa.cpp
+++ b/src/mesa/program/ir_to_mesa.cpp
@@ -2757,6 +2757,8 @@ ir_to_mesa_visitor::copy_propagate(void)
       /* If this is a copy, add it to the ACP. */
       if (inst->op == OPCODE_MOV &&
 	  inst->dst.file == PROGRAM_TEMPORARY &&
+	  !(inst->dst.file == inst->src[0].file &&
+	    inst->dst.index == inst->src[0].index) &&
 	  !inst->dst.reladdr &&
 	  !inst->saturate &&
 	  !inst->src[0].reladdr &&
-- 
1.8.1.2