[Openmp-commits] [flang] [llvm] [mlir] [openmp] [MLIR][OpenMP] Add omp.fuse operation (PR #168898)

[Michael Kruse via Openmp-commits]

================
@@ -6527,6 +6527,117 @@ static void addAccessGroupMetadata(BasicBlock *Block, MDNode *AccessGroup,
   }
 }
 
+CanonicalLoopInfo *
+OpenMPIRBuilder::fuseLoops(DebugLoc DL, ArrayRef<CanonicalLoopInfo *> Loops) {
+
+  CanonicalLoopInfo *firstLoop = Loops.front();
+  CanonicalLoopInfo *lastLoop = Loops.back();
+  Function *F = firstLoop->getPreheader()->getParent();
+
+  // Loop control blocks that will become orphaned later
+  SmallVector<BasicBlock *> oldControlBBs;
+  for (CanonicalLoopInfo *Loop : Loops)
+    Loop->collectControlBlocks(oldControlBBs);
+
+  // Collect original trip counts
+  SmallVector<Value *> origTripCounts;
+  for (CanonicalLoopInfo *L : Loops) {
+    assert(L->isValid() && "All input loops must be valid canonical loops");
+    origTripCounts.push_back(L->getTripCount());
+  }
+
+  Builder.SetCurrentDebugLocation(DL);
+
+  // Compute max trip count.
+  // The fused loop will be from 0 to max(origTripCounts)
+  BasicBlock *TCBlock = BasicBlock::Create(F->getContext(), "omp.fuse.comp.tc",
+                                           F, firstLoop->getHeader());
+  Builder.SetInsertPoint(TCBlock);
+  Value *fusedTripCount = nullptr;
+  for (CanonicalLoopInfo *L : Loops) {
+    assert(L->isValid() && "All loops to fuse must be valid canonical loops");
+    Value *origTripCount = L->getTripCount();
+    if (!fusedTripCount) {
+      fusedTripCount = origTripCount;
+      continue;
+    }
+    Value *condTP = Builder.CreateICmpSGT(fusedTripCount, origTripCount);
+    fusedTripCount = Builder.CreateSelect(condTP, fusedTripCount, origTripCount,
+                                          Twine(".omp.fuse.tc"));
----------------
Meinersbur wrote:

```suggestion
                                          ".omp.fuse.tc");
```
[nit] use implicit converson

https://github.com/llvm/llvm-project/pull/168898