glsl: provide the option of using BFE for unpack builting lowering

This greatly improves generated code, especially for the snorm variants,
since it is able to get rid of the lshift/rshift for sext, as well as
replacing each shift + mask with a single op.

Signed-off-by: Ilia Mirkin <[email protected]>
Reviewed-by: Matt Turner <[email protected]>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/glsl/ir_builder.cpp b/src/glsl/ir_builder.cpp
index cd03859cac0..c9cf1240dfe 100644
--- a/src/glsl/ir_builder.cpp
+++ b/src/glsl/ir_builder.cpp
@@ -567,6 +567,12 @@ csel(operand a, operand b, operand c)
 }
 
 ir_expression *
+bitfield_extract(operand a, operand b, operand c)
+{
+   return expr(ir_triop_bitfield_extract, a, b, c);
+}
+
+ir_expression *
 bitfield_insert(operand a, operand b, operand c, operand d)
 {
    void *mem_ctx = ralloc_parent(a.val);