Currently, a node and its users are added back to the worklist in reverse topological order after it is combined. This diff changes that order to be topological. This is part of a larger migration to get the DAGCombiner to process nodes in topological order.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D127115
Currently, a node and its users are added back to the worklist in reverse topological order after it is combined. This diff changes that order to be topological. This is part of a larger migration to get the DAGCombiner to process nodes in topological order.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D127115
This is another fold generalized from D111530.
We can find a common source for a rotate operation hidden inside an 'or':
https://alive2.llvm.org/ce/z/9pV8hn
Deciding when this is profitable vs. a funnel-shift is tricky, but this
does not show any regressions: if a target has a rotate but it does not
have a funnel-shift, then try to form the rotate here. That is why we
don't have x86 test diffs for the scalar tests that are duplicated from
AArch64 ( 74a65e3834d9487 ) - shld/shrd are available. That also makes it
difficult to show vector diffs - the only case where I found a diff was
on x86 AVX512 or XOP with i64 elements.
There's an additional check for a legal type to avoid a problem seen
with x86-32 where we form a 64-bit rotate but then it gets split
inefficiently. We might avoid that by adding more rotate folds, but
I didn't check to see what is missing on that path.
This gets most of the motivating patterns for AArch64 / ARM that are in
D111530.
We still need a couple of enhancements to setcc pattern matching with
rotate/funnel-shift to get the rest.
Differential Revision: https://reviews.llvm.org/D120933
LOGIC (LOGIC (SH X0, Y), Z), (SH X1, Y) --> LOGIC (SH (LOGIC X0, X1), Y), Z
https://alive2.llvm.org/ce/z/QmR9rR
This is a reassociation + factoring fold. The common shift operation is moved
after a bitwise logic op on 2 input operands.
We get simpler cases of these patterns in IR, but I suspect we would miss all
of these exact tests in IR too. We also handle the simpler form of this plus
several other folds in DAGCombiner::hoistLogicOpWithSameOpcodeHands().
This is a partial implementation of a transform suggested in D111530
(only handles 'or' bitwise logic as a first step - need to stamp out more
tests for other opcodes).
Several of the same tests added for D111530 are altered here (but not
fully optimized). I'm not sure yet if this would help/hinder that patch,
but this should be an improvement for all tests added with ecf606cb4329ae
since it removes a shift operation in those examples.
Differential Revision: https://reviews.llvm.org/D120516
