From 473a3e7fed16ec27db398047d29082ce6cf9d318 Mon Sep 17 00:00:00 2001
From: Alexey Bataev <a.bataev@hotmail.com>
Date: Tue, 15 Nov 2016 09:11:50 +0000
Subject: [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
---
 clang/lib/CodeGen/CodeGenFunction.h | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

(limited to 'clang/lib/CodeGen/CodeGenFunction.h')

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
-- 
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