The original test case showed a problem with the independet blocks pass and
we decided to XFAIL it for now. Unfortunately the failure is not detected if
we build without asserts and the verification of the independent block pass
is not run. This change tests now for the actual reason of the failure and
should trigger even in a non asserts build. We did not yet solve the underlying
bug, but this should at least make the test suite behavior consistent.
llvm-svn: 183025
When the Polly code generation was written we did not correctly update the
LoopInfo data, but still claimed that the loop information is correct. This
does not only lead to missed optimizations, but it can also cause
miscompilations in case passes such as LoopSimplify are run after Polly.
Reported-by: Sergei Larin <slarin@codeaurora.org>
llvm-svn: 181987
BeforeBB
|
v
GuardBB
/ \
__ PreHeaderBB \
/ \ / |
latch HeaderBB |
\ / \ /
< \ /
\ /
ExitBB
This does not only remove the need for an explicit loop rotate pass, but it also
gives us the possibility to skip the construction of the guard condition in case
the loop is known to be executed at least once. We do not yet exploit this, but
by implementing this analysis in the isl code generator we should be able to
remove more guards than the generic loop rotate pass can. Another point is that
loop rotation can introduce additional PHI nodes, which may hide that a loop can
be executed in parallel. This change avoids this complication and will make it
easier to move the openmp code generation into a separate pass.
llvm-svn: 181986
In the classical (non -polly-codegen-scev) mode, we assume that we can always
recreate PHI nodes during code generation. This is not true. We can only
reconstruct them from the polyhedral information, in case the entire loop of the
PHI node is part of the SCoP and consequently the PHI node was translated in
the polyhedral description.
llvm-svn: 179674
We now support regions with multiple entries and multiple exits natively.
Regions are not needed to be simplified to single entry and single exit.
We need to XFAIL two test cases as this change increases the scop coverage
and uncoveres two failures in the independent blocks pass. The first failure
will be fixed in a subsequent commit, the second one is in the non-default
-polly-codegen-scev mode and still needs to be fixed.
Contributed-by: Star Tan <tanmx_star@yeah.net>
llvm-svn: 179673
Regions that have multiple entry edges are very common. A simple if condition
yields e.g. such a region:
if
/ \
then else
\ /
for_region
This for_region contains two entry edges 'then' -> 'for_region' and 'else' -> 'for_region'.
Previously we scheduled the RegionSimplify pass to translate such regions into
simple regions. With this patch, we now support them natively when the region is
in -loop-simplify form, which means the entry block should not be a loop header.
Contributed by: Star Tan <tanmx_star@yeah.net>
llvm-svn: 179586
Regions that have multiple exit edges are very common. A simple if condition
yields e.g. such a region:
if
/ \
then else
\ /
after
Region: if -> after
This regions contains the bbs 'if', 'then', 'else', but not 'after'. It has
two exit edges 'then' -> 'after' and 'else' -> 'after'.
Previously we scheduled the RegionSimplify pass to translate such regions into
simple regions. With this patch, we now support them natively.
Contributed-by: Star Tan <tanmx_star@yeah.net>
llvm-svn: 179159
Given the following code
for (i = 0; i < 10; i++) {
;
}
S: A[i] = 0
When code generating S using scev based code generation, we need to retrieve
the scev of 'i' at the location of 'S'. If we do not do this the scev that
we obtain will be expressed as {0,+,1}_for and will reference loop iterators
that do not surround 'S' and that we consequently do not know how to code
generate. What we really want is the scev to be instantiated to the value of 'i'
after the loop. This value is {10} and it can be code generated without
troubles.
llvm-svn: 177777
When doing SCEV based code generation, we ignore instructions calculating values
that are fully defined by a SCEV expression. The values that are calculated by
this instructions are recalculated on demand.
This commit improves the check to verify if certain instructions can be ignored
and recalculated on demand.
llvm-svn: 177313
We need to remove one dimension. Any is correct as long as it exists. We have
choosen for whatever reason the dimension #dims - 2. This is incorrect if
there is just one dimension. For CLooG this case did never happen. For isl
however, the case can happen and causes undefined behavior including crashes.
We choose now always the last dimension #dims - 1. We could have choosen
dimension '0' but the last dimension is what we remove conceptionally in the
algorithm, so it seems better to actually program it that way.
While at it remove another piece of undefined behavior.
llvm-svn: 174894
Tobias Grosser