This CL splits the lowering of affine to LLVM into 2 parts:
1. affine -> std
2. std -> LLVM
The conversions mostly consists of splitting concerns between the affine and non-affine worlds from existing conversions.
Short-circuiting of affine `if` conditions was never tested or exercised and is removed in the process, it can be reintroduced later if needed.
LoopParametricTiling.cpp is updated to reflect the newly added ForOp::build.
PiperOrigin-RevId: 257794436
Change the AsmPrinter to number values breadth-first so that values in adjacent regions can have the same name. This allows for ModuleOp to contain operations that produce results. This also standardizes the special name of region entry arguments to "arg[0-9+]" now that Functions are also operations.
PiperOrigin-RevId: 257225069
This implements the lowering of `floordiv`, `ceildiv` and `mod` operators from
affine expressions to the arithmetic primitive operations. Integer division
rules in affine expressions explicitly require rounding towards either negative
or positive infinity unlike machine implementations that round towards zero.
In the general case, implementing `floordiv` and `ceildiv` using machine signed
division requires computing both the quotient and the remainder. When the
divisor is positive, this can be simplified by adjusting the dividend and the
quotient by one and switching signs.
In the current use cases, we are unlikely to encounter affine expressions with
negative divisors (affine divisions appear in loop transformations such as
tiling that guarantee that divisors are positive by construction). Therefore,
it is reasonable to use branch-free single-division implementation. In case of
affine maps, divisors can only be literals so we can check the sign and
implement the case for negative divisors when the need arises.
The affine lowering pass can still fail when applied to semi-affine maps
(division or modulo by a symbol).
PiperOrigin-RevId: 228668181
This change is mechanical and merges the LowerAffineApplyPass and
LowerIfAndForPass into a single LowerAffinePass. It makes a step towards
defining an "affine dialect" that would contain all polyhedral-related
constructs. The motivation for merging these two passes is based on retiring
MLFunctions and, eventually, transforming If and For statements into regular
operations. After that happens, LowerAffinePass becomes yet another
legalization.
PiperOrigin-RevId: 227566113
Nicolas Vasilache