LoopDistribute/LAA: Respect convergent
This case is slightly tricky, because loop distribution should be
allowed in some cases, and not others. As long as runtime dependency
checks don't need to be introduced, this should be OK. This is further
complicated by the fact that LoopDistribute partially ignores if LAA
says that vectorization is safe, and then does its own runtime pointer
legality checks.
Note this pass still does not handle noduplicate correctly, as this
should always be forbidden with it. I'm not going to bother trying to
fix it, as it would require more effort and I think noduplicate should
be removed.
https://reviews.llvm.org/D62607
llvm-svn: 363160
diff --git a/llvm/lib/Transforms/Scalar/LoopDistribute.cpp b/llvm/lib/Transforms/Scalar/LoopDistribute.cpp
index 4f5344b..f45e5fd 100644
--- a/llvm/lib/Transforms/Scalar/LoopDistribute.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopDistribute.cpp
@@ -766,8 +766,14 @@
"cannot isolate unsafe dependencies");
}
- // Don't distribute the loop if we need too many SCEV run-time checks.
+ // Don't distribute the loop if we need too many SCEV run-time checks, or
+ // any if it's illegal.
const SCEVUnionPredicate &Pred = LAI->getPSE().getUnionPredicate();
+ if (LAI->hasConvergentOp() && !Pred.isAlwaysTrue()) {
+ return fail("RuntimeCheckWithConvergent",
+ "may not insert runtime check with convergent operation");
+ }
+
if (Pred.getComplexity() > (IsForced.getValueOr(false)
? PragmaDistributeSCEVCheckThreshold
: DistributeSCEVCheckThreshold))
@@ -795,7 +801,14 @@
auto Checks = includeOnlyCrossPartitionChecks(AllChecks, PtrToPartition,
RtPtrChecking);
+ if (LAI->hasConvergentOp() && !Checks.empty()) {
+ return fail("RuntimeCheckWithConvergent",
+ "may not insert runtime check with convergent operation");
+ }
+
if (!Pred.isAlwaysTrue() || !Checks.empty()) {
+ assert(!LAI->hasConvergentOp() && "inserting illegal loop versioning");
+
MDNode *OrigLoopID = L->getLoopID();
LLVM_DEBUG(dbgs() << "\nPointers:\n");