[OPENMP] Fixed codegen for 'omp cancel' construct.

If 'omp cancel' construct is used in a worksharing construct it may cause
hanging of the software in case if reduction clause is used. Patch fixes
this problem by avoiding extra reduction processing for branches that
were canceled.

llvm-svn: 286944

1 files changed, 29 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index e5ca9bc980e..6e974520b35 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -982,6 +982,35 @@ private:
   };
   SmallVector<BreakContinue, 8> BreakContinueStack;
 
+  /// Data for exit block for proper support of OpenMP cancellation constructs.
+  struct OMPCancel {
+    JumpDest ExitBlock;
+    llvm::function_ref<void(CodeGenFunction &CGF)> CodeGen;
+    OMPCancel() : CodeGen([](CodeGenFunction &CGF) {}) {}
+  };
+  SmallVector<OMPCancel, 8> OMPCancelStack;
+
+  /// Controls insertion of cancellation exit blocks in worksharing constructs.
+  class OMPCancelStackRAII {
+    CodeGenFunction &CGF;
+
+  public:
+    OMPCancelStackRAII(CodeGenFunction &CGF) : CGF(CGF) {
+      CGF.OMPCancelStack.push_back({});
+    }
+    ~OMPCancelStackRAII() {
+      if (CGF.HaveInsertPoint() &&
+          CGF.OMPCancelStack.back().ExitBlock.isValid()) {
+        auto CJD = CGF.getJumpDestInCurrentScope("cancel.cont");
+        CGF.EmitBranchThroughCleanup(CJD);
+        CGF.EmitBlock(CGF.OMPCancelStack.back().ExitBlock.getBlock());
+        CGF.OMPCancelStack.back().CodeGen(CGF);
+        CGF.EmitBranchThroughCleanup(CJD);
+        CGF.EmitBlock(CJD.getBlock());
+      }
+    }
+  };
+
   CodeGenPGO PGO;
 
   /// Calculate branch weights appropriate for PGO data