4 Commits

Author SHA1 Message Date
Tom Eccles
53cc33b00b [flang] Store KindMapping by value in FirOpBuilder
Previously only a constant reference was stored in the FirOpBuilder.
However, a lot of code was merged using

FirOpBuilder builder{rewriter, getKindMapping(mod)};

This is incorrect because the KindMapping returned will go out of scope
as soon as FirOpBuilder's constructor had run. This led to an infinite
loop running some tests using HLFIR (because the stack space containing
the kind mapping was re-used and corrupted).

One solution would have just been to fix the incorrect call sites,
however, as a large number of these had already made it past review, I
decided to instead change FirOpBuilder to store its own copy of the
KindMapping. This is not costly because nearly every time we construct a
KindMapping is exclusively to construct a FirOpBuilder. To make this
common pattern simpler, I added a new constructor to FirOpBuilder which
calls getKindMapping().

Differential Revision: https://reviews.llvm.org/D151881
2023-06-05 09:57:57 +00:00
Mats Petersson
b812932b35 [FLANG] Change loop versioning to use shift instead of divide
Despite me being convinced that the use of divide didn't produce any
divide instructions, it does in fact add more instructions than using
a plain shift operation.

This patch simply changes the divide to a shift right, with an
assert to check that the "divisor" is a power of two.

Reviewed By: kiranchandramohan, tblah

Differential Revision: https://reviews.llvm.org/D151880
2023-06-01 19:29:57 +01:00
Mats Petersson
b75f9ce3fe [FLANG] Support all arrays for LoopVersioning
This patch makes more than 2D arrays work, with a fix for the way that
loop index is calculated. Removing the restriction of number of
dimensions.

This also changes the way that the actual index is calculated, such that
the stride is used rather than the extent of the previous dimension. Some
tests failed without fixing this - this was likely a latent bug in the
2D version too, but found in a test using 3D arrays, so wouldn't
have been found with 2D only. This introduces a division on the index
calculation - however it should be a nice and constant value allowing
a shift to be used to actually divide - or otherwise removed by using
other methods to calculate the result. In analysing code generated with
optimisation at -O3, there are no divides produced.

Some minor refactoring to avoid repeatedly asking for the "rank" of the
array being worked on.

This improves some of the SPEC-2017 ROMS code, in the same way as the
limited 2D array improvements - less overhead spent calculating array
indices in the inner-most loop and better use of vector-instructions.

Reviewed By: kiranchandramohan

Differential Revision: https://reviews.llvm.org/D151140
2023-05-30 18:54:40 +01:00
Mats Petersson
a716ace13d Add loop-versioning pass to improve unit-stride
Introduce conditional code to identify stride of "one element", and simplify the array accesses for that case.

This allows better loop performance in various benchmarks.

Reviewed By: tblah, kiranchandramohan

Differential Revision: https://reviews.llvm.org/D141306
2023-04-18 09:53:07 +01:00