2022 ICCAD Problem B

Problem B: 3D Placement with D2D Vertical Connections

Author Chi-En Ho Chieh-En Wang

2022 ICCAD Problem B website: http://iccad-contest.org/Problems.html

Synchronize this note and source code in github: https://github.com/coherent17/2022-ICCAD-Problem-B

[TOC]

Introduction:

Spilt a large die into two or more small dies and increase the yield, and better cost! In this Problem, we are going to partition a large die into 2 dies with the same sizes. Try to find the placement of the standard cell and the hybrid bonding so that minimize the Half-Perimeter Wirelength(HPWL)

Goal:

Minimum the HPWL of the 3D placement

Constraints:

• The total number of hybrid bonding terminals is limited.
• All the hybrid bonding terminals need to be placed on the top-most layer of the die with required terminal size and terminal spacing requirement.
• Each inter-die connections need to have 1 and only 1 hybrid bonding terminal.
• The technology process of the 2 dies will be given.
• The cell size, cell height, cell pin location of the same logical library cell would be different in each technology.
• The center point of the hybrid bonding terminals needs to be included in the HPWL calculation for each die.
• All the cells need to be placed on row and cannot have overlap with each other.
• Max placement utilization constraint must be satisfied.
• The minimum resolution of all the coordinate values is integer.

Procedure

1. Partition the big dies into 2 dies (maybe use shemetis?)
2. Place and legalize both the top die and bottom die.
3. Place the Hydrogen Bond so that minimize the HPWL

Input Format

1. Netlist

Syntax

NumInstances <instanceCount> 
Inst <instName> <libCellName> 
NumNets <netCount> 
Net <netName> <numPins> 
Pin <instName>/<libPinName> 

Example

NumInstances 2 
Inst C1 MC1 
Inst C2 MC3 
NumNets 1 
Net N1 2 
Pin C1/P2 
Pin C2/P1 

2. Die size for both bottom die and top die (would be the same)

Syntax

DieSize <lowerLeftX> <lowerLeftY> <upperRightX> <upperRightY> 

Example

DieSize 0 0 500 450 

3. Max placement utilization ratio for each die

Syntax

TopDieMaxUtil <util> 
BottomDieMaxUtil <util> 

Example

TopDieMaxUtil 75 
BottomDieMaxUtil 80 

4. Placement rows of each die

• The given rows would start from (0, 0) and cover the entire die.

Syntax

TopDieRows <startX> <startY> <rowLength> <rowHeight> <repeatCount> 
BottomDieRows <startX> <startY> <rowLength> <rowHeight> <repeatCount> 

Example

TopDieRows 0 0 500 10 45 
BottomDieRows 0 0 500 15 30 

5. Std cell library for each die.

• If the 2 dies are with different technologies, the given std cell library for each die would have equivalent logic

Syntax

NumTechnologies <technologyCount> 
Tech <techName> <libCellCount> 
LibCell <libCellName> <libCellSizeX> <libCellSizeY> <pinCount> 
Pin <pinName> <pinLocationX> <pinLocationY> 

Example

NumTechnologies 2 
Tech TA 2 
LibCell MC1 5 10 1 
Pin P1 2 7 
LibCell MC2 7 10 2 
Pin P1 5 3 
Pin P2 3 6 
Tech TB 2 
LibCell MC1 5 15 1 
Pin P1 2 11 
LibCell MC2 7 15 2 
Pin P1 2 12 
Pin P2 3 3 

6. Hybrid bonding terminal size & the required spacing

• Hybrid bonding terminal size & the required spacing between 2 terminals and between terminal and die boundary

Syntax

TerminalSize <sizeX> <sizeY> 
TerminalSpacing <spacing> 

Example

TerminalSize 20 20 
TerminalSpacing 15 

Output Format

1. Top die placement result

Syntax

TopDiePlacement <InstCount> 
Inst <instName> <locationX> <locationY> 

Example

TopDiePlacement 2 
Inst C1 0 10
Inst C4 15 20 

2. Bottom die placement result

Syntax

BottomDiePlacement <InstCount> 
Inst <instName> <locationX> <locationY> 

Example

BottomDiePlacement 3 
Inst C2 20 15 
Inst C3 23 30 
Inst C5 50 15 

3. Hybrid bonding terminal placement result with net information

Syntax

    NumTerminals <TerminalCount> 
    Terminal <netName> <locationX> <locationY> 

Example

    NumTerminals 2 
    Terminal N1 100 200 
    Terminal N3 180 180 

• Use the same coordinate system for each die, of which bottom-left points are both $(0,0)$.
• The outputted coordinate is lower-left coordinate of the cell.
• All the cells can NOT be flipped nor mirrored.

Evaluation

To Do List

• Learn Cuda or Pthread or Openmp to parallel programming
• Parse the input testcase with format
• Write a global timer. (Runtime limit: 1hr)
• 2-way partition (shemetis?)
• Placement the Standard Cell by simulate annealing
  • Stage 1
    • Standard Cell are moved between different rows and in the same row.
    • Standard Cell overlaps are allowed.
    • When the temperature is reached below a certain value,stage 2 begins.
  • Stage 2
    • Remove overlaps.
    • Annealing process continues, but only interchanges adjacent standard cells within the same row.
• Placement the Hybrid Bonding by calculating the bounding box.
• Calculate $HPWL_{top\ die} + HPWL_{bottom\ die}$
• Replacement if needed
• Output the result with format