i965/vs: Add a function to fix-up uniform arguments for 3-src insts.

Three-source instructions have a vertical stride overloaded to 4, which
prevents directly using vec4 uniforms as arguments. Instead we need to
insert a MOV instruction to do the replication for the three-source
instruction.

With this in place, we can use three-source instructions in the vertex
shader. While some thought needs to go into deciding whether its better
to use a three-source instruction rather than a sequence of equivalent
instructions (when one or more sources are uniforms or immediates), this
will allow us to skip a lot of ugly lowering code and use the BFE and
BFI2 instructions directly.

Reviewed-by: Chris Forbes <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_vec4.h b/src/mesa/drivers/dri/i965/brw_vec4.h
index 697ab86918b..c28092244a4 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.h
+++ b/src/mesa/drivers/dri/i965/brw_vec4.h
@@ -430,6 +430,8 @@ public:
    void emit_scs(ir_instruction *ir, enum prog_opcode op,
 		 dst_reg dst, const src_reg &src);
 
+   src_reg fix_3src_operand(src_reg src);
+
    void emit_math1_gen6(enum opcode opcode, dst_reg dst, src_reg src);
    void emit_math1_gen4(enum opcode opcode, dst_reg dst, src_reg src);
    void emit_math(enum opcode opcode, dst_reg dst, src_reg src);