[Seq] Lower FirRomOp to HWModuleGeneratedOp #5800
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Add a new `FirRomOp` to the Seq dialect to capture the semantics of FIRRTL ROM at the HW level. The intent behind this change is the same as for `FirMemOp`. ROMs are represented as a declaration with the `seq.firrom` which returns a value representing the ROM itself. This value is of type `!seq.firrom<12 x 42>` which represents an opaque handle to the ROM; it encodes the `depth (12)` and `width (42)` of the ROM. ROM ports are represented as separate operations: - `seq.firrom.read_port` These operations take the ROM itself as their first operand. The remaining operands are the specific signals required for the corresponding type of port: clocks, enables, mode select, etc. Read ports also return the read data as their result. Enables are optional to allow for more concise IR for simple memory configurations. The reason why adding a new `FirRomOp` instead of reusing the `FirMemOp` to process Read-Only-Memory is because there are still huge differences in the behaviors of ROM, SRAM, and RegFile in different foundry memory compilers, and their DFT processing is also very different. If they are all merged into `FirMemOp`, a lot of attributes must be added to `FirMemOp`, resulting in the post-processing having to judge these attributes, which increases the burden of post-processing. Therefore, adding `FirRomOp` as a new op is conducive to behavior distinction and later maintenance, especially when we want to add DFT and physical implementation details in the real chip design process, it will be more conducive to implementation, and reduce the cost of code errors caused by maintenance. This commit merely adds the `FirRomOp` alongside some canonicalization and general tests, but the op isn't used by any part of CIRCT yet. Use in FIRRTL-to-HW lowering follows as a separate commit. Signed-off-by: Huang Rui <[email protected]>
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SpriteOvO
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Aug 9, 2023
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Add the `LowerFirRom` pass which lowers `seq.firrom` ops to a corresponding `hw.module.generated` op. The pass collects a list of ROM ops in the design, distills them down into ROM parameters, deduplicates those parameters, creates one `hw.module.generated` op for each unique ROM config, and replaces the ROM ops with instances of this generated module. This commit reflects that ROM can configure the `numReadPorts` parameter, because there are multi-port ROMs, for example: https://www.intel.com/content/dam/altera-www/global/en_US/others/support/examples/download/dual_port_rom.zip Signed-off-by: Huang Rui <[email protected]>
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Add the
LowerFirRompass which lowersseq.firromops to acorresponding
hw.module.generatedop. The pass collects a listof ROM ops in the design, distills them down into ROM parameters,
deduplicates those parameters, creates one
hw.module.generatedopfor each unique ROM config, and replaces the ROM ops with instances
of this generated module.
This commit reflects that ROM can configure the
numReadPortsparameter, because there are multi-port ROMs, for example:
https://www.intel.com/content/dam/altera-www/global/en_US/others/support/examples/download/dual_port_rom.zip
This commit blocked by: #5798