[llvm] [OpenMP] [IR Builder] Changes to Support Scan Operation (PR #136035)

[Michael Kruse via llvm-commits]

================
@@ -508,6 +508,30 @@ class OpenMPIRBuilder {
       return allocaInst;
     }
   };
+
+  struct ScanInformation {
+    /// Dominates the body of the loop before scan directive
+    llvm::BasicBlock *OMPBeforeScanBlock = nullptr;
+    /// Dominates the body of the loop before scan directive
+    llvm::BasicBlock *OMPAfterScanBlock = nullptr;
+    /// Controls the flow to before or after scan blocks
+    llvm::BasicBlock *OMPScanDispatch = nullptr;
+    /// Exit block of loop body
+    llvm::BasicBlock *OMPScanLoopExit = nullptr;
+    /// Block before loop body where scan initializations are done
+    llvm::BasicBlock *OMPScanInit = nullptr;
+    /// Block after loop body where scan finalizations are done
+    llvm::BasicBlock *OMPScanFinish = nullptr;
+    /// If true, it indicates Input phase is lowered; else it indicates
+    /// ScanPhase is lowered
+    bool OMPFirstScanLoop = false;
+    // Maps the private reduction variable to the pointer of the temporary
+    // buffer
+    llvm::SmallDenseMap<llvm::Value *, llvm::Value *> ScanBuffPtrs;
+    llvm::Value *IV;
+    llvm::Value *Span;
+  } ScanInfo;
----------------
Meinersbur wrote:

```suggestion
  };
```

Usually it is not a good idea remember such data between methods calls. Better pass a handle object between methods calls, such as `AtomicInfo` and `CanonicalLoopInfo`.

The type would consistently be called `ScanInfo`.

https://github.com/llvm/llvm-project/pull/136035