Hi,
This patch implements support for the following directives :
- `!DIR$ NOUNROLL_AND_JAM` to disable unrolling and jamming on a DO
LOOP.
- `!DIR$ NOUNROLL` to disable unrolling on a DO LOOP.
- `!DIR$ NOVECTOR` to disable vectorization on a DO LOOP.
This patch implements support for the UNROLL_AND_JAM directive to enable
or disable unrolling and jamming on a `DO LOOP`.
It must be placed immediately before a `DO LOOP` and applies only to the
loop that follows. N is an integer that specifying the unrolling factor.
This is done by adding an attribute to the branch into the loop in LLVM
to indicate that the loop should unrolled and jammed.
This patch implements support for the UNROLL directive to control how
many times a loop should be unrolled.
It must be placed immediately before a `DO LOOP` and applies only to the
loop that follows. N is an integer that specifying the unrolling factor.
This is done by adding an attribute to the branch into the loop in LLVM
to indicate that the loop should unrolled.
The code pushed to support the directive `VECTOR ALWAYS` has been
modified to take account of the fact that several directives can be used
before a `DO LOOP`.
The current pattern was failing OpenACC semantics in acc parse tree
canonicalization:
```
!acc loop
!dir vector aligned
do i=1,n
...
```
Fix it by moving the directive before the OpenACC construct node.
Note that I think it could make sense to propagate the $dir info to the
acc.loop, at least with classic flang, the $dir seems to make a
difference. This is not done here since few directives are supported
anyway.
This patch implements support for the VECTOR ALWAYS directive, which
forces
vectorization to occurr when possible regardless of a decision by the
cost
model. This is done by adding an attribute to the branch into the loop
in LLVM
to indicate that the loop should always be vectorized.
This patch only implements this directive on plan structured do loops
without labels. Support for unstructured loops and array
expressions is planned for future patches.
