Loop peeling is currently performed as part of UnrollLoop().
Outside test scenarios, it is always performed with an unroll
count of 1. This means that unrolling doesn't actually do anything
apart from performing post-unroll simplification.
When testing, it's currently possible to specify both an explicit
peel count and an explicit unroll count. This doesn't perform any
sensible operation and may result in miscompiles, see
https://bugs.llvm.org/show_bug.cgi?id=45939.
This patch moves peeling from UnrollLoop() into tryToUnrollLoop(),
so that peeling does not also perform a susequent unroll. We only
run the post-unroll simplifications. Specifying both an explicit
peel count and unroll count is forbidden.
In the future, we may want to support both (non-PGO) peeling a
loop and unrolling it, but this needs to be done by first performing
the peel and then recalculating unrolling heuristics on a now
possibly analyzable loop.
Differential Revision: https://reviews.llvm.org/D103362
As it's causing some bot failures (and per request from kbarton).
This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.
llvm-svn: 358546
I forgot to specify -unroll-loop-peel, making this test not
really effective. While here, adjust some details (naming and
run line). Thanks to Sanjoy and Michael Z. for pointing out in
their post-commit reviews.
llvm-svn: 312015
When peeling kicks in, it updates the loop preheader.
Later, a successful full unroll of the loop needs to update a PHI
which i-th argument comes from the loop preheader, so it'd better look
at the correct block. Fixes PR33437.
Differential Revision: https://reviews.llvm.org/D37153
llvm-svn: 311922
Nikita Popov