[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.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@286944 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/CGStmtOpenMP.cpp b/lib/CodeGen/CGStmtOpenMP.cpp
index 937295e6600fcb645fb30e28bf35db6c24c916d6..a791663c2cfe5f13d7bf38d21ddba8d97943544e 100644 (file)
--- a/lib/CodeGen/CGStmtOpenMP.cpp
+++ b/lib/CodeGen/CGStmtOpenMP.cpp
@@ -1781,9 +1781,17 @@ void CodeGenFunction::EmitOMPOuterLoop(bool DynamicOrOrdered, bool IsMonotonic,
   EmitBlock(LoopExit.getBlock());
 
   // Tell the runtime we are done.
-  if (!DynamicOrOrdered)
-    RT.emitForStaticFinish(*this, S.getLocEnd());
+  SourceLocation ELoc = S.getLocEnd();
+  auto &&CodeGen = [DynamicOrOrdered, ELoc](CodeGenFunction &CGF) {
+    if (!DynamicOrOrdered)
+      CGF.CGM.getOpenMPRuntime().emitForStaticFinish(CGF, ELoc);
+  };
+  CodeGen(*this);
 
+  OpenMPDirectiveKind DKind = S.getDirectiveKind();
+  if (DKind == OMPD_for || DKind == OMPD_parallel_for ||
+      DKind == OMPD_distribute_parallel_for)
+    OMPCancelStack.back().CodeGen = CodeGen;
 }
 
 void CodeGenFunction::EmitOMPForOuterLoop(
@@ -1895,6 +1903,7 @@ void CodeGenFunction::EmitOMPDistributeOuterLoop(
 void CodeGenFunction::EmitOMPDistributeParallelForDirective(
     const OMPDistributeParallelForDirective &S) {
   OMPLexicalScope Scope(*this, S, /*AsInlined=*/true);
+  OMPCancelStackRAII CancelRegion(*this);
   CGM.getOpenMPRuntime().emitInlinedDirective(
       *this, OMPD_distribute_parallel_for,
       [&S](CodeGenFunction &CGF, PrePostActionTy &) {
@@ -2123,7 +2132,15 @@ bool CodeGenFunction::EmitOMPWorksharingLoop(const OMPLoopDirective &S) {
                          [](CodeGenFunction &) {});
         EmitBlock(LoopExit.getBlock());
         // Tell the runtime we are done.
-        RT.emitForStaticFinish(*this, S.getLocStart());
+        SourceLocation ELoc = S.getLocEnd();
+        auto &&CodeGen = [ELoc](CodeGenFunction &CGF) {
+          CGF.CGM.getOpenMPRuntime().emitForStaticFinish(CGF, ELoc);
+        };
+        CodeGen(*this);
+        OpenMPDirectiveKind DKind = S.getDirectiveKind();
+        if (DKind == OMPD_for || DKind == OMPD_parallel_for ||
+            DKind == OMPD_distribute_parallel_for)
+          OMPCancelStack.back().CodeGen = CodeGen;
       } else {
         const bool IsMonotonic =
             Ordered || ScheduleKind.Schedule == OMPC_SCHEDULE_static ||
@@ -2177,6 +2194,7 @@ void CodeGenFunction::EmitOMPForDirective(const OMPForDirective &S) {
   };
   {
     OMPLexicalScope Scope(*this, S, /*AsInlined=*/true);
+    OMPCancelStackRAII CancelRegion(*this);
     CGM.getOpenMPRuntime().emitInlinedDirective(*this, OMPD_for, CodeGen,
                                                 S.hasCancel());
   }
@@ -2313,7 +2331,12 @@ void CodeGenFunction::EmitSections(const OMPExecutableDirective &S) {
     CGF.EmitOMPInnerLoop(S, /*RequiresCleanup=*/false, &Cond, &Inc, BodyGen,
                          [](CodeGenFunction &) {});
     // Tell the runtime we are done.
-    CGF.CGM.getOpenMPRuntime().emitForStaticFinish(CGF, S.getLocStart());
+    SourceLocation ELoc = S.getLocEnd();
+    auto &&CodeGen = [ELoc](CodeGenFunction &CGF) {
+      CGF.CGM.getOpenMPRuntime().emitForStaticFinish(CGF, ELoc);
+    };
+    CodeGen(CGF);
+    CGF.OMPCancelStack.back().CodeGen = CodeGen;
     CGF.EmitOMPReductionClauseFinal(S);
     // Emit post-update of the reduction variables if IsLastIter != 0.
     emitPostUpdateForReductionClause(
@@ -2351,6 +2374,7 @@ void CodeGenFunction::EmitSections(const OMPExecutableDirective &S) {
 void CodeGenFunction::EmitOMPSectionsDirective(const OMPSectionsDirective &S) {
   {
     OMPLexicalScope Scope(*this, S, /*AsInlined=*/true);
+    OMPCancelStackRAII CancelRegion(*this);
     EmitSections(S);
   }
   // Emit an implicit barrier at the end.
@@ -2438,6 +2462,7 @@ void CodeGenFunction::EmitOMPParallelForDirective(
   // Emit directive as a combined directive that consists of two implicit
   // directives: 'parallel' with 'for' directive.
   auto &&CodeGen = [&S](CodeGenFunction &CGF, PrePostActionTy &) {
+    OMPCancelStackRAII CancelRegion(CGF);
     CGF.EmitOMPWorksharingLoop(S);
   };
   emitCommonOMPParallelDirective(*this, S, OMPD_for, CodeGen);
@@ -2458,6 +2483,7 @@ void CodeGenFunction::EmitOMPParallelSectionsDirective(
   // Emit directive as a combined directive that consists of two implicit
   // directives: 'parallel' with 'sections' directive.
   auto &&CodeGen = [&S](CodeGenFunction &CGF, PrePostActionTy &) {
+    OMPCancelStackRAII CancelRegion(CGF);
     CGF.EmitSections(S);
   };
   emitCommonOMPParallelDirective(*this, S, OMPD_sections, CodeGen);
@@ -3438,8 +3464,11 @@ CodeGenFunction::getOMPCancelDestination(OpenMPDirectiveKind Kind) {
   if (Kind == OMPD_parallel || Kind == OMPD_task)
     return ReturnBlock;
   assert(Kind == OMPD_for || Kind == OMPD_section || Kind == OMPD_sections ||
-         Kind == OMPD_parallel_sections || Kind == OMPD_parallel_for);
-  return BreakContinueStack.back().BreakBlock;
+         Kind == OMPD_parallel_sections || Kind == OMPD_parallel_for ||
+         Kind == OMPD_distribute_parallel_for);
+  if (!OMPCancelStack.back().ExitBlock.isValid())
+    OMPCancelStack.back().ExitBlock = getJumpDestInCurrentScope("cancel.exit");
+  return OMPCancelStack.back().ExitBlock;
 }
 
 void CodeGenFunction::EmitOMPUseDevicePtrClause(

diff --git a/lib/CodeGen/CodeGenFunction.h b/lib/CodeGen/CodeGenFunction.h
index e5ca9bc980e02130b0f0b3ec6f9dba93b3d7d92c..6e974520b35c9f9ccf7e1be427576fac589a4961 100644 (file)
--- a/lib/CodeGen/CodeGenFunction.h
+++ b/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

diff --git a/test/OpenMP/cancel_codegen.cpp b/test/OpenMP/cancel_codegen.cpp
index fb0a4dd54a227c3f39c5b9ec96d9c5a159178271..768d2c0bd7a6ff498728eee8f4c7b4183d6430b9 100644 (file)
--- a/test/OpenMP/cancel_codegen.cpp
+++ b/test/OpenMP/cancel_codegen.cpp
@@ -90,9 +90,11 @@ for (int i = 0; i < argc; ++i) {
   }
 }
 // CHECK: call void (%ident_t*, i32, void (i32*, i32*, ...)*, ...) @__kmpc_fork_call(
-#pragma omp parallel for
+int r = 0;
+#pragma omp parallel for reduction(+:r)
 for (int i = 0; i < argc; ++i) {
 #pragma omp cancel for
+  r += i;
 }
 // CHECK: call void (%ident_t*, i32, void (i32*, i32*, ...)*, ...) @__kmpc_fork_call(
   return argc;
@@ -163,6 +165,9 @@ for (int i = 0; i < argc; ++i) {
 // CHECK: [[CONTINUE]]
 // CHECK: br label
 // CHECK: call void @__kmpc_for_static_fini(
+// CHECK: call i32 @__kmpc_reduce_nowait(
+// CHECK: call void @__kmpc_end_reduce_nowait(
+// CHECK: call void @__kmpc_for_static_fini(
 // CHECK: ret void
 
 #endif