i965: Don't copy propagate bitcasts with source modifiers.

Previously, copy propagation would cause bitcast_f2u(abs(float)) to
be performed in a single step, but the application of source modifiers
(abs, neg) happens after type conversion, leading to incorrect results.

That is, for bitcast_f2u(abs(float)) we would in fact generate code to
do abs(bitcast_f2u(float)).

For example, whereas bitcast_f2u(abs(float)) might result in a register
argument such as
   (abs)g2.2<0,1,0>UD

v2: Set interfered = true and break in register_coalesce instead of
    returning false.

Reviewed-by: Paul Berry <stereoytpe441@gmail.com>

1 files changed, 6 insertions, 4 deletions

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 c28d0de..fdbe96c 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
@@ -206,14 +206,16 @@ vec4_visitor::try_copy_propagation(vec4_instruction *inst, int arg,
    if (inst->src[arg].negate)
       value.negate = !value.negate;
 
-   bool has_source_modifiers = (value.negate || value.abs ||
-                                value.swizzle != BRW_SWIZZLE_XYZW ||
-                                value.file == UNIFORM);
+   bool has_source_modifiers = value.negate || value.abs;
 
    /* gen6 math and gen7+ SENDs from GRFs ignore source modifiers on
     * instructions.
     */
-   if (has_source_modifiers && !can_do_source_mods(inst))
+   if ((has_source_modifiers || value.file == UNIFORM ||
+        value.swizzle != BRW_SWIZZLE_XYZW) && !can_do_source_mods(inst))
+      return false;
+
+   if (has_source_modifiers && value.type != inst->src[arg].type)
       return false;
 
    bool is_3src_inst = (inst->opcode == BRW_OPCODE_LRP ||