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IC Compiler Implementation User Guide Version D-2010.03-SP2
12. Physical Datapath With Relative Placement
Introduction to Physical Datapath With Relative Placement . . . . . . . . . . . . . . . . . . . 12-3
Benefits of Relative Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-4
Flow for Relative Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-5
Methodology for the Relative Placement Flow. . . . . . . . . . . . . . . . . . . . . . . . . . 12-6
Sample Script for a Relative Placement Flow . . . . . . . . . . . . . . . . . . . . . . . . . . 12-7
Considerations for Using Relative Placement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-8
Creating Relative Placement Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-9
Anchoring Relative Placement Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-12
Applying Compression to Relative Placement Groups . . . . . . . . . . . . . . . . . . . 12-14
Supporting Compression With Mixed Alignment . . . . . . . . . . . . . . . . . . . . 12-14
Adding Objects to a Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-15
Adding Leaf Cells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-15
Specifying Orientation for Leaf Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-16
Aligning Leaf Cells Within a Column. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-17
Orientation of Relative Placement Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-22
Relative Placement Group Orientations . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-22
Relative Placement Cell Orientations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-24
Controlling Relative Placement Cell Orientations . . . . . . . . . . . . . . . . . . . . 12-25
Adding Relative Placement Groups. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-26
Benefits of Hierarchical Relative Placement Groups . . . . . . . . . . . . . . . . . 12-27
Including Relative Placement Groups. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-27
Instantiating Relative Placement Groups . . . . . . . . . . . . . . . . . . . . . . . . . . 12-29
Using Hierarchical Relative Placement for Straddling . . . . . . . . . . . . . . . . 12-31
Using Hierarchical Relative Placement for Compression . . . . . . . . . . . . . . 12-32
Effect of Ungrouping on Hierarchical Relative Placement . . . . . . . . . . . . . 12-34
Effect of Uniquifying on Hierarchical Relative Placement. . . . . . . . . . . . . . 12-36
Adding Keepouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-37
Placement of Relative Placement Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-39
Performing Relative Placement in a Design Containing Obstructions . . . . . . . . 12-39
Handling Physical-Only Cells During Relative Placement . . . . . . . . . . . . . . . . . 12-40
Performing Relative Placement in a Design Containing Tap Cells. . . . . . . . . . . 12-41
Using Move Bounds to Constrain Relative Placement . . . . . . . . . . . . . . . . . . . 12-41
Adding Incremental Relative Placement Groups . . . . . . . . . . . . . . . . . . . . . . . . 12-42
Controlling Movement When Legalizing Relative Placement Groups . . . . . . . . 12-43
Supporting Relative Placement Groups in Virtual Flat Placement . . . . . . . . . . 12-43