[Mesa-dev] [PATCH v2 020/103] i965/vec4: don't copy propagate vector opcodes that operate in align1 mode

[Iago Toral Quiroga]

Basically, ALIGN1 mode will ignore swizzles on the input vectors so we don't
want the copy propagation pass to mess with them.
---
 .../drivers/dri/i965/brw_vec4_copy_propagation.cpp | 24 ++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
index 545f4c7..d0045a7 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
@@ -283,6 +283,22 @@ try_constant_propagate(const struct gen_device_info *devinfo,
 }
 
 static bool
+is_align1_opcode(unsigned opcode)
+{
+   switch (opcode) {
+   case VEC4_OPCODE_DOUBLE_TO_FLOAT:
+   case VEC4_OPCODE_FLOAT_TO_DOUBLE:
+   case VEC4_OPCODE_PICK_LOW_32BIT:
+   case VEC4_OPCODE_PICK_HIGH_32BIT:
+   case VEC4_OPCODE_SET_LOW_32BIT:
+   case VEC4_OPCODE_SET_HIGH_32BIT:
+      return true;
+   default:
+      return false;
+   }
+}
+
+static bool
 try_copy_propagate(const struct gen_device_info *devinfo,
                    vec4_instruction *inst, int arg,
                    const copy_entry *entry, int attributes_per_reg)
@@ -326,6 +342,14 @@ try_copy_propagate(const struct gen_device_info *devinfo,
 
    unsigned composed_swizzle = brw_compose_swizzle(inst->src[arg].swizzle,
                                                    value.swizzle);
+
+   /* Instructions that operate on vectors in ALIGN1 mode will ignore swizzles
+    * so copy-propagation won't be safe if the composed swizzle is anything
+    * other than the identity.
+    */
+   if (is_align1_opcode(inst->opcode) && composed_swizzle != BRW_SWIZZLE_XYZW)
+      return false;
+
    if (inst->is_3src(devinfo) &&
        (value.file == UNIFORM ||
         (value.file == ATTR && attributes_per_reg != 1)) &&
-- 
2.7.4