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[CombToAIG] Add support for div/mod operations #8130

Merged
merged 1 commit into from
Feb 3, 2025
Merged

[CombToAIG] Add support for div/mod operations #8130

merged 1 commit into from
Feb 3, 2025

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uenoku
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@uenoku uenoku commented Jan 25, 2025 •
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This patch adds support for lowering comb div/mod operations to AIG:

  • Support unsigned div/mod for power-of-2 constant divisors
  • Support for non-power-of-2 divisors by emulating the operation with a mux tree when the number of unknown bits is small (default threshold is 10 bits). This is not ideal and eventually we should lower to a proper div/mod. Practically this lowering pattern covers many cases since users rarely use div/mod because these operations are very expensive (users write their own div/mod in their frontend language).
  • LEC tests are added.

@uenoku uenoku force-pushed the dev/hidetou/aig-divmod branch 2 times, most recently from 88c68a8 to 3b11ca9 Compare January 25, 2025 10:31
@uenoku uenoku force-pushed the dev/hidetou/aig-divmod branch from 3b11ca9 to 46077e1 Compare January 25, 2025 19:15
@uenoku
[CombToAIG] Add support for div/mod operations
cda5bbd 
This patch adds support for lowering comb div/mod operations to AIG:
* Support for power-of-2 constant divisors by converting to shifts
* Support for non-power-of-2 divisors by emulating the operation with a mux tree
  when the number of unknown bits is small (default threshold: 10 bits)
* Support for both signed and unsigned div/mod operations
* Added integration tests to verify correctness
@uenoku uenoku force-pushed the dev/hidetou/aig-divmod branch from 46077e1 to cda5bbd Compare January 25, 2025 19:16
fabianschuiki
fabianschuiki approved these changes Feb 3, 2025
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LGTM! I agree that people will mostly build their own dividers, since there are so many different architectures. In the long run there might be a "simple" long division that AIG could lower to.

@uenoku uenoku merged commit ee62dbc into llvm:main Feb 3, 2025
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@uenoku @fabianschuiki