================
@@ -3543,13 +3543,67 @@ static ConstantInt *getKnownValueOnEdge(Value *V,
BasicBlock *From,
return nullptr;
}
+static bool isUncontrolledConvergentCall(CallBase *CB) {
+ return CB->isConvergent() && !isa<ConvergenceControlInst>(CB) &&
+ !CB->getConvergenceControlToken();
+}
+
+static bool reachesUncontrolledConvergentCallBeforeBlock(BasicBlock *From,
+ BasicBlock *StopBB) {
+ // Walk predecessors of StopBB to find blocks that can reach it. Only
+ // convergent calls on a cycle with StopBB matter - a convergent call on a
+ // path to function exit cannot have its dynamic instance changed by
+ // threading.
+ SmallPtrSet<BasicBlock *, 8> CanReachStop;
+ SmallVector<BasicBlock *, 8> Worklist;
+ for (BasicBlock *Pred : predecessors(StopBB))
+ Worklist.push_back(Pred);
+
+ while (!Worklist.empty()) {
+ BasicBlock *BB = Worklist.pop_back_val();
+ if (BB == StopBB)
+ continue;
+ if (!CanReachStop.insert(BB).second)
+ continue;
+ if (CanReachStop.size() > MaxJumpThreadingLiveBlocks)
+ return true;
+ append_range(Worklist, predecessors(BB));
+ }
+
+ if (!CanReachStop.contains(From))
+ return false;
+
+ SmallPtrSet<BasicBlock *, 8> Visited;
+ Worklist.push_back(From);
+
+ while (!Worklist.empty()) {
+ BasicBlock *BB = Worklist.pop_back_val();
+ if (BB == StopBB || !CanReachStop.contains(BB))
+ continue;
+
+ if (!Visited.insert(BB).second)
+ continue;
+ if (Visited.size() > MaxJumpThreadingLiveBlocks)
----------------
shiltian wrote:
> I'm not sure I like overloading MaxJumpThreadingLiveBlocks here.
Yeah, fair. Do you want me to add a new option here, though I'm not sure how
much it will help? Alternatively, I can just hard-code a number there.
> Also, the amount of work we do here is also proportional to the size of the
> basic blocks.
Right, but I don't see how to further improve this. Basically we want to check
if there is any convergent calls inside a BB.
https://github.com/llvm/llvm-project/pull/204958
_______________________________________________
llvm-branch-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
