Fixed-point PoC

[KFAFSP]

We want to create a fixed-point only PoC implementation that incorporates the new design and specification elements.

• [x] Make a branch for the PoC
• [x] Remove floating-point and constant folding components to be able to change the interface quickly
• [x] Remove limit on E for fixed-point (32bits?)
• [ ] Implement Elaborator for issues #2 , #5 , #6
  • Can we already show the similarity between fixed and floating by following the frexp/ldexp scheme?
  • Is there a way to turn constant results into type parameters while elaborating (make fixed from const exp)?
  • Is there 1 best method of rounding? If not, how do we allow the user to select it?
  • How many bits can we use and how can the user chose a different path (promotion pass)?
  • How to seperate the responsibilities (add alias operations vs elaborator method)?
• [ ] Create experiments for the demo

[KFAFSP]

This would also have to incorporate the change to the limits on E for fixed-point!

[HahaLan97]

What I've done:

• [x] Creat a new branch heart23 and remove floating point semantics and folders for ops.

• [x] Change FixedPointType from <integerBits, fractionalBits> to <bitWidth, exponent> and modify the FixedPointSemantics interface and FixedPointInterpreter to adjust this.

• [x] Create Pass ConvertBase2ToArith, which now converts

• base2.bit_cast to arith.bitcast

• base2.value_cast to arith.trunci/extsi/extui

• base2.fixed.add to base2.value_cast and arith.addi

• [x] example of --convert-base2-to-arith:

  
  !type1 = !base2.fixed_point<signed 6, -3>
  !type2 = !base2.fixed_point<unsigned 4, -2>
  !type3 = !base2.fixed_point<signed 7, -3>

func.func @test(%arg0: !type1, %arg1: !type2) -> !type3 { %0 = base2.fixed.add %arg0, %arg1 : !type1, !type2 return %0 : !type3 }

func.func @test(%arg0: i6, %arg1: i4) -> i7 { %0 = arith.extsi %arg0 : i6 to i7 %1 = arith.extui %arg1 : i4 to i7 %2 = arith.addi %0, %1 : i7 return %2 : i7 }

What still needs to think of:

- [ ] fixed.op's return type
- [ ] #6 -> How to deal with rounding modes.
- [ ] elaborator methods
- [ ] other ops to add