diff options
author | long.chen <lipracer@gmail.com> | 2024-10-12 23:25:57 +0800 |
---|---|---|
committer | GitHub <noreply@github.com> | 2024-10-12 11:25:57 -0400 |
commit | 51a2f50ee76a52d4a542822bfda9c4c17904b72f (patch) | |
tree | 6f7876416c1a5018ac8d0560dfc0caa6226b16c0 /clang/test/CodeGenCXX/PR6474.cpp | |
parent | c9a1cffd3d2129ccdda766ef4379dbca1cf6724b (diff) | |
download | llvm-main.zip llvm-main.tar.gz llvm-main.tar.bz2 |
[mlir][affine] fix the issue of ceildiv-mul-ceildiv form expression not satisfying commutative (#111254)HEADmain
my prove:
we can simple `(n * s) ceildiv a ceildiv s` to `n ceildiv a`
because `(n * s) ceildiv a ceildiv b` <=> `(n * s) ceildiv s ceildiv a`
<=> `n ceildiv a`
let's prove the `s floordiv a floor b` <=> `s floordiv b floor a`
let `s = ka +m (m < a)` so `s floordiv a` <=> `s / a - m / a`
similarly, it can be proven that:
`s floordiv a floordiv b` <=> `s / (a * b) - m / (a * b) - n / (b) constrain (n < b)`
<=> `s / (a * b) - (m + a*n) / (a*b)`
because `a* b - (m + a*n)` <=> `a*b - a*n - m` > `a - m` > `0`
so `s floordiv a floordiv b` <=> `[s / (a*b)]` <=> `s floordiv b floordiv a`
but if `s floordiv b` mutiply a factor above didn't always hold true.
Fixes https://github.com/llvm/llvm-project/issues/107508
Diffstat (limited to 'clang/test/CodeGenCXX/PR6474.cpp')
0 files changed, 0 insertions, 0 deletions