doc: Add deprecation warning about breadth_first router to docs
diff --git a/doc/src/vpr/command_line_usage.rst b/doc/src/vpr/command_line_usage.rst
index f2ad858..ef5bb26 100644
--- a/doc/src/vpr/command_line_usage.rst
+++ b/doc/src/vpr/command_line_usage.rst
@@ -829,7 +829,14 @@
Selects which router algorithm to use.
- The ``breadth_first`` router focuses solely on routing a design successfully, while the ``timing_driven`` router focuses both on achieving a successful route and achieving good circuit speed.
+ .. warning::
+
+ The ``breadth_first`` router **should NOT be used to compare the run-time/quality** of alternate routing algorithms.
+
+ It is inferrior to the ``timing_driven`` router from a circuit speed (2x - 10x slower) and run-time perspective (takes 10-100x longer on the large benchmarks).
+ The ``breadth_first`` router is deprecated and may be removed in a future release.
+
+ The ``breadth_first`` router :cite:`betz_arch_cad` focuses solely on routing a design successfully, while the ``timing_driven`` router :cite:`betz_arch_cad,murray_air` focuses both on achieving a successful route and achieving good circuit speed.
The breadth-first router is capable of routing a design using slightly fewer tracks than the timing-driving router (typically 5% if the timing-driven router uses its default parameters.
This can be reduced to about 2% if the router parameters are set so the timing-driven router pays more attention to routability and less to area).
diff --git a/doc/src/z_references.bib b/doc/src/z_references.bib
index 7c599d1..130439f 100644
--- a/doc/src/z_references.bib
+++ b/doc/src/z_references.bib
@@ -390,3 +390,10 @@
month={Dec},
}
+@INPROCEEDINGS{murray_air,
+ author={K. E. Murray and S. Zhong and V. Betz},
+ booktitle={To appear in Asia Pacific Design Automation Conference (ASP-DAC)},
+ title={AIR: A Fast but Lazy Timing-Driven FPGA Router},
+ year={2020},
+ doi={}
+}
