pan/bi: Add fexp2 implementation

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4615>
diff --git a/src/panfrost/bifrost/compiler.h b/src/panfrost/bifrost/compiler.h
index 2d3f1a1..ec9a4ad 100644
--- a/src/panfrost/bifrost/compiler.h
+++ b/src/panfrost/bifrost/compiler.h
@@ -558,6 +558,10 @@
         return list_first_entry(&(block->link), pan_block, link);
 }
 
+/* Special functions */
+
+void bi_emit_fexp2(bi_context *ctx, nir_alu_instr *instr);
+
 /* BIR manipulation */
 
 bool bi_has_outmod(bi_instruction *ins);