3D OPIN-CHANZ connectivity #3323

soheilshahrouz · 2025-10-28T15:53:20Z

Removes the pin_offset attribute from the architecture file, which was previously used to model 3D OPIN connectivity.
Instead, the <fc_override> tag is now used to specify absolute fc values for connecting OPINs to CHANZ wire segments.

Additionally, several functions have been moved from rr_graph2.cpp to two new files: rr_graph_chan_chan_edges.cpp and rr_graph_opin_chan_edges.cpp.

…raph_sg

AmirhosseinPoolad

What a PR, Soheil. Had some thoughts, mostly on styling. I did not review rr_graph_chan_chan_edges.cpp/h and rr_graph_opin_chan_edges.cpp/h as you said it was only moving the code to a new file.

Also only reviewed add_edges_opin_chanz_per_side and add_edges_opin_chanz_per_block in rr_graph_sg for the same reason.

AmirhosseinPoolad · 2025-11-12T20:10:52Z

libs/librrgraph/src/base/get_parallel_segs.h

                                             e_parallel_axis parallel_axis,
                                             bool keep_original_index = false);
+
+int get_parallel_seg_index(int abs,


Needs doxygen

AmirhosseinPoolad · 2025-11-12T20:18:10Z

libs/librrgraph/src/base/rr_spatial_lookup.h

                                                       e_rr_type rr_type) const;

+
+    std::vector<RRNodeId> find_pin_nodes_at_side(int layer,


AmirhosseinPoolad · 2025-11-12T20:25:28Z

vpr/src/route/rr_graph_generation/build_scatter_gathers.cpp

                                  scatter_wire_candidates.size());

-                    continue;
+                    // continue;


Remove commented out code

AmirhosseinPoolad · 2025-11-12T20:27:32Z

vpr/src/route/rr_graph_generation/clock_network_builders.cpp

+    seg_idx = get_parallel_seg_index(drive_seg_idx, indices_map, e_parallel_axis::X_AXIS);
+    drive_seg_idx = (seg_idx >= 0) ? seg_idx : drive_seg_idx;

-    get_parallel_seg_index(left_seg_idx, e_parallel_axis::X_AXIS, indices_map);
+    seg_idx = get_parallel_seg_index(left_seg_idx, indices_map, e_parallel_axis::X_AXIS);
+    left_seg_idx = (seg_idx >= 0) ? seg_idx : left_seg_idx;

-    get_parallel_seg_index(right_seg_idx, e_parallel_axis::X_AXIS, indices_map);
+    seg_idx = get_parallel_seg_index(right_seg_idx, indices_map, e_parallel_axis::X_AXIS);
+    right_seg_idx = (seg_idx >= 0) ? seg_idx : right_seg_idx;


Rename drive_seg_idx, left_seg_idx and right_seg_idx to have underlines after them. Not clear in a glance that they're private fields and not consistent with the rest of the code base.

AmirhosseinPoolad · 2025-11-12T20:29:10Z

vpr/src/route/rr_graph_generation/rr_graph.cpp

 *   @param perturb_switch_pattern Specifies whether connections should be distributed unevenly across the channel or not.
 *   @param directionality Segment directionality: should be either *UNI-DIRECTIONAL* or *BI-DIRECTIONAL* 
 *   @param seg_inf Segments type information, such as length, frequency, and etc.
 *   @param sets_per_seg_type Number of available sets within the channel_width of each segment type.
 * 
- * @return an 5D matrix which keeps the track indicies connected to each pin ([0..num_pins-1][0..width-1][0..height-1][0..layer-1][0..sides-1]).
+ * @return an 4D matrix which keeps the track indices connected to each pin ([0..num_pins-1][0..width-1][0..height-1][0..layer-1][0..sides-1]).


It's still 5 dimensions in the comment. '([0..num_pins-1][0..width-1][0..height-1][0..layer-1][0..sides-1])'

AmirhosseinPoolad · 2025-11-12T22:36:31Z

vpr/src/route/rr_graph_generation/rr_graph_sg.h

+                                   t_rr_edge_info_set& rr_edges_to_create,
+                                   const vtr::NdMatrix<std::vector<t_bottleneck_link>, 2>& interdie_3d_links);
+
+void add_edges_opin_chanz_per_block(const RRGraphView& rr_graph,


AmirhosseinPoolad · 2025-11-12T22:37:47Z

vpr/src/route/rr_graph_generation/rr_types.h

 * [0..device_ctx.physical_tile_types.size()-1][0..num_pins-1][0..width][0..height][0..layer-1][0..3][0..Fc-1] */
-typedef std::vector<vtr::NdMatrix<std::vector<int>, 5>> t_pin_to_track_lookup;
+typedef std::vector<vtr::NdMatrix<std::vector<int>, 4>> t_pin_to_track_lookup;


Update the comment above (remove layer)

AmirhosseinPoolad · 2025-11-12T22:39:19Z

vpr/src/route/rr_graph_generation/rr_types.h

 * 
 * Note that when we model different channels based on position not axis, we can't use this anymore and need to have a lookup for each grid location. */
-typedef std::vector<vtr::NdMatrix<std::vector<int>, 5>> t_track_to_pin_lookup;
+typedef std::vector<vtr::NdMatrix<std::vector<int>, 4>> t_track_to_pin_lookup;


Update comment above.

AmirhosseinPoolad · 2025-11-12T22:40:56Z

vtr_flow/arch/multi_die/simple_arch/3d_k4_N4_90nm.xml

+        <!-- Gather 30 connections from the end of L4 wires at all four sides of a switchblock location -->
+        <wireconn num_conns="0" from_type="L1" from_switchpoint="1" side="rltb"/>
+      </gather>
+      <scatter>
+        <!-- Scatter 30 connections to the start of L4 wires at all four sides of a switchblock location -->
+        <wireconn num_conns="30" to_type="L1" to_switchpoint="0" side="rtlb"/>
+      </scatter>
+      <sg_link_list>
+        <!-- Link going up one layer, using the 'seg4_inter_die_driver' multiplexer to gather connections from the bottom layer and using the LZ node/wire to move up one layer -->
+        <sg_link name="L_UP" z_offset="1" x_offset="0" y_offset="0" mux="segz_driver" seg_type="LZ"/>
+        <!-- Link going down one layer, using the 'seg4_inter_die_driver' multiplexer to gather connections from the top layer and using the LZ node/wire to down up one layer -->
+        <sg_link name="L_DOWN" z_offset="-1" mux="segz_driver" seg_type="LZ"/>
+      </sg_link_list>
+      <!-- Instantiate 6 'L_UP' and 6 'L_DOWN' sg_links per switchblock location everywhere on the device -->


Update the comments here to represent the architecture.

AmirhosseinPoolad · 2025-11-12T22:42:19Z

vtr_flow/arch/multi_die/stratixiv_3d/3d_full_OPIN_inter_die_stratixiv_arch.timing.xml

+  <!-- Specify a scatter-gather pattern for 3D connections. -->
+  <scatter_gather_list>
+    <sg_pattern name="name" type="unidir">
+      <gather>
+        <!-- Gather 30 connections from the end of L4 wires at all four sides of a switchblock location -->
+        <wireconn num_conns="0" from_type="L4" from_switchpoint="3" side="rltb"/>
+      </gather>
+      <scatter>
+        <!-- Scatter 30 connections to the start of L4 wires at all four sides of a switchblock location -->
+        <wireconn num_conns="30" to_type="L4" to_switchpoint="0" side="rtl"/>
+      </scatter>
+      <sg_link_list>
+        <!-- Link going up one layer, using the 'seg4_inter_die_driver' multiplexer to gather connections from the bottom layer and using the LZ node/wire to move up one layer -->
+        <sg_link name="L_UP" z_offset="1" x_offset="0" y_offset="0" mux="seg4_inter_die_driver" seg_type="LZ"/>
+        <!-- Link going down one layer, using the 'seg4_inter_die_driver' multiplexer to gather connections from the top layer and using the LZ node/wire to down up one layer -->
+        <sg_link name="L_DOWN" z_offset="-1" mux="seg4_inter_die_driver" seg_type="LZ"/>
+      </sg_link_list>
+      <!-- Instantiate 6 'L_UP' and 6 'L_DOWN' sg_links per switchblock location everywhere on the device -->
+      <sg_location type="EVERYWHERE" num="60" sg_link_name="L_UP"/>
+      <sg_location type="EVERYWHERE" num="60" sg_link_name="L_DOWN"/>
+    </sg_pattern>
+  </scatter_gather_list>


Update comments.

soheilshahrouz added 5 commits October 10, 2025 15:13

clean some comments

c3ea108

clean get_track_to_pins a bit

cd680d7

remove direct pin to other layer's track connectivity

8294d2d

remove arch_inter_die_switch

6857133

Merge remote-tracking branch 'origin/master' into temp_opin_chanz

271ed58

github-actions bot added VPR VPR FPGA Placement & Routing Tool libarchfpga Library for handling FPGA Architecture descriptions lang-cpp C/C++ code labels Oct 28, 2025

soheilshahrouz added 9 commits October 28, 2025 15:53

remove pin layer offset and ipin_cblock_switch_index_between_dice

bd51bd9

remove layer_offset from rr_graph.cpp

2c37b80

Merge remote-tracking branch 'origin/master' into temp_opin_chanz

5e5b118

doxygen comment for process_fc()

c5d509c

Merge branch 'temp_arch_xml_naming_convention' into temp_opin_chanz

a9b490a

doxygen comment for label_wire_muxes()

1f13be8

Fc for OPIN-CHANZ can be 1

4104e23

update the 3d_full_opin arch file

027ab8b

add OPIN--CHANZ edges

9210a3d

github-actions bot added the libvtrutil label Nov 1, 2025

soheilshahrouz added 12 commits November 1, 2025 15:03

move get_parallel_seg_index() to get_parallel_sets.cpp

f747061

move add_edges_opin_chanz to rr_graph_3d

230fead

remove pins_connected() function and rename rr_graph_3d files to rr_g…

0097c56

…raph_sg

move add_and_connect_non_3d_sg_links() to rr_graph_sg

d2af592

noexcept for strongid methods

21dfd5d

use the correct layer for CHANZ nodes when initalizing src_opin_delays

6803792

allow OPIN to be connected to CHANZ in check_adjacent()

1ede4c4

make format

ea14ba1

add find_pin_nodes_at_side() to RRSpatialLookup

78afdc2

add add_edges_opin_chanz_per_side()

0dcb2fa

update inter_layer_connections_limited_to_opin() to check OPIN-CHANZ

72e130c

some cleanups in rr_graph files

3610503

soheilshahrouz added 11 commits November 5, 2025 14:04

add rr_graph_opin_chan_edges files

a577480

doxygen comment for add_opin_chan_edges()

109896e

make format

d7b67ea

doxygen comments for some function in rr_graph_opin_chan_edges

9a12593

add rr_graph_chan_chan_edges

fd6d5c5

add rr_chanz_segment_width to DeviceContext

63cbe06

calculate acc_tile_num_inter_die_conn_ using pre-computed chanz width

5d477c1

Merge remote-tracking branch 'origin/master' into temp_opin_chanz

27cbc2a

update expected_delay_cost before VTR_ASSERT

eadc8fe

add sg and z segment to 3d_k4_n4_90nm

2657db0

remove duplication get_parallel_seg_index() function

55db1c8

soheilshahrouz changed the title ~~[WIP] 3D OPIN-CHANZ connectivity~~ 3D OPIN-CHANZ connectivity Nov 10, 2025

soheilshahrouz requested review from AmirhosseinPoolad, amin1377 and vaughnbetz November 10, 2025 23:00

soheilshahrouz added 2 commits November 10, 2025 18:09

update golden results for vtr_strong/strong_ap/basic_3d_ap/

644fe8a

don't update segment index if not found

e76138f

AmirhosseinPoolad reviewed Nov 12, 2025

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3D OPIN-CHANZ connectivity #3323

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		e_rr_type rr_type) const;


		std::vector<RRNodeId> find_pin_nodes_at_side(int layer,

3D OPIN-CHANZ connectivity #3323

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soheilshahrouz commented Oct 28, 2025 •

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