[OPENMP50]Codegen for inscan reductions in worksharing directives.

Summary:
Implemented codegen for reduction clauses with inscan modifiers in
worksharing constructs.

Emits the code for the directive with inscan reductions.
The code is the following:
```
size num_iters = <num_iters>;
<type> buffer[num_iters];
for (i: 0..<num_iters>) {
  <input phase>;
  buffer[i] = red;
}
for (int k = 0; k != ceil(log2(num_iters)); ++k)
for (size cnt = last_iter; cnt >= pow(2, k); --k)
  buffer[i] op= buffer[i-pow(2,k)];
for (0..<num_iters>) {
  red = InclusiveScan ? buffer[i] : buffer[i-1];
  <scan phase>;
}
```

Reviewers: jdoerfert

Subscribers: yaxunl, guansong, arphaman, cfe-commits, caomhin

Tags: #clang

Differential Revision: https://reviews.llvm.org/D79948

1 files changed, 29 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index e3dd462..2b0ebad 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -673,6 +673,32 @@ public:
 
   llvm::BasicBlock *getInvokeDestImpl();
 
+  /// Parent loop-based directive for scan directive.
+  const OMPExecutableDirective *OMPParentLoopDirectiveForScan = nullptr;
+  llvm::BasicBlock *OMPBeforeScanBlock = nullptr;
+  llvm::BasicBlock *OMPAfterScanBlock = nullptr;
+  llvm::BasicBlock *OMPScanExitBlock = nullptr;
+  llvm::BasicBlock *OMPScanDispatch = nullptr;
+  bool OMPFirstScanLoop = false;
+
+  /// Manages parent directive for scan directives.
+  class ParentLoopDirectiveForScanRegion {
+    CodeGenFunction &CGF;
+    const OMPExecutableDirective &ParentLoopDirectiveForScan;
+
+  public:
+    ParentLoopDirectiveForScanRegion(
+        CodeGenFunction &CGF,
+        const OMPExecutableDirective &ParentLoopDirectiveForScan)
+        : CGF(CGF),
+          ParentLoopDirectiveForScan(*CGF.OMPParentLoopDirectiveForScan) {
+      CGF.OMPParentLoopDirectiveForScan = &ParentLoopDirectiveForScan;
+    }
+    ~ParentLoopDirectiveForScanRegion() {
+      CGF.OMPParentLoopDirectiveForScan = &ParentLoopDirectiveForScan;
+    }
+  };
+
   template <class T>
   typename DominatingValue<T>::saved_type saveValueInCond(T value) {
     return DominatingValue<T>::save(*this, value);
@@ -3201,7 +3227,8 @@ public:
   /// proper codegen in internal captured statement.
   ///
   void EmitOMPReductionClauseInit(const OMPExecutableDirective &D,
-                                  OMPPrivateScope &PrivateScope);
+                                  OMPPrivateScope &PrivateScope,
+                                  bool ForInscan = false);
   /// Emit final update of reduction values to original variables at
   /// the end of the directive.
   ///
@@ -3260,6 +3287,7 @@ public:
   void EmitOMPTaskgroupDirective(const OMPTaskgroupDirective &S);
   void EmitOMPFlushDirective(const OMPFlushDirective &S);
   void EmitOMPDepobjDirective(const OMPDepobjDirective &S);
+  void EmitOMPScanDirective(const OMPScanDirective &S);
   void EmitOMPOrderedDirective(const OMPOrderedDirective &S);
   void EmitOMPAtomicDirective(const OMPAtomicDirective &S);
   void EmitOMPTargetDirective(const OMPTargetDirective &S);