[Mesa-dev] [PATCH v3] nir/copy_propagate: do not copy-propagate MOV srcs with source modifiers

[Iago Toral Quiroga]

If a source operand in a MOV has source modifiers, then we cannot
copy-propagate it from the parent instruction and remove the MOV.

v2: remove the check for source modifiers from is_move() (Jason)

v3: Put the check for source modifiers back into is_move() since
    this function is called from copy_prop_alu_src(). Add source
    modifiers checks to is_vec() instead.
---

Jason, I had to revert v2 after noticing this, I did not realize that is_move()
was actually called from another place when you suggested removing the check
from there so I did not think that it could possibly break anything and did not
pass v2 through piglit again. Obviously I was wrong, sorry about that :-(

This version does not produce any regressions in piglit in my IVB laptop.

 src/glsl/nir/nir_opt_copy_propagate.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/glsl/nir/nir_opt_copy_propagate.c b/src/glsl/nir/nir_opt_copy_propagate.c
index 7d8bdd7..cfc8e331 100644
--- a/src/glsl/nir/nir_opt_copy_propagate.c
+++ b/src/glsl/nir/nir_opt_copy_propagate.c
@@ -55,10 +55,15 @@ static bool is_move(nir_alu_instr *instr)
 
 static bool is_vec(nir_alu_instr *instr)
 {
-   for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++)
+   for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
       if (!instr->src[i].src.is_ssa)
          return false;
 
+      /* we handle modifiers in a separate pass */
+      if (instr->src[i].abs || instr->src[i].negate)
+         return false;
+   }
+
    return instr->op == nir_op_vec2 ||
           instr->op == nir_op_vec3 ||
           instr->op == nir_op_vec4;
-- 
1.9.1