[OPENMP] Fix for PR28581: OpenMP linear clause - wrong results.
If worksharing construct has at least one linear item, an implicit
synchronization point must be emitted to avoid possible conflict with
the loading/storing values to the original variables. Added implicit
barrier if the linear item is found before actual start of the
worksharing construct.
llvm-svn: 311013
diff --git a/clang/lib/CodeGen/CGStmtOpenMP.cpp b/clang/lib/CodeGen/CGStmtOpenMP.cpp
index c76835f..1b14882 100644
--- a/clang/lib/CodeGen/CGStmtOpenMP.cpp
+++ b/clang/lib/CodeGen/CGStmtOpenMP.cpp
@@ -1231,12 +1231,14 @@
EmitBlock(LoopExit.getBlock());
}
-void CodeGenFunction::EmitOMPLinearClauseInit(const OMPLoopDirective &D) {
+bool CodeGenFunction::EmitOMPLinearClauseInit(const OMPLoopDirective &D) {
if (!HaveInsertPoint())
- return;
+ return false;
// Emit inits for the linear variables.
+ bool HasLinears = false;
for (const auto *C : D.getClausesOfKind<OMPLinearClause>()) {
for (auto *Init : C->inits()) {
+ HasLinears = true;
auto *VD = cast<VarDecl>(cast<DeclRefExpr>(Init)->getDecl());
if (auto *Ref = dyn_cast<DeclRefExpr>(VD->getInit()->IgnoreImpCasts())) {
AutoVarEmission Emission = EmitAutoVarAlloca(*VD);
@@ -1261,6 +1263,7 @@
EmitIgnoredExpr(CS);
}
}
+ return HasLinears;
}
void CodeGenFunction::EmitOMPLinearClauseFinal(
@@ -1550,7 +1553,7 @@
CGF.EmitOMPSimdInit(S);
emitAlignedClause(CGF, S);
- CGF.EmitOMPLinearClauseInit(S);
+ (void)CGF.EmitOMPLinearClauseInit(S);
{
OMPPrivateScope LoopScope(CGF);
CGF.EmitOMPPrivateLoopCounters(S, LoopScope);
@@ -2170,7 +2173,7 @@
llvm::DenseSet<const Expr *> EmittedFinals;
emitAlignedClause(*this, S);
- EmitOMPLinearClauseInit(S);
+ bool HasLinears = EmitOMPLinearClauseInit(S);
// Emit helper vars inits.
std::pair<LValue, LValue> Bounds = CodeGenLoopBounds(*this, S);
@@ -2184,7 +2187,7 @@
// Emit 'then' code.
{
OMPPrivateScope LoopScope(*this);
- if (EmitOMPFirstprivateClause(S, LoopScope)) {
+ if (EmitOMPFirstprivateClause(S, LoopScope) || HasLinears) {
// Emit implicit barrier to synchronize threads and avoid data races on
// initialization of firstprivate variables and post-update of
// lastprivate variables.
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 4b8e7c0..c87e4d1 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -2761,7 +2761,9 @@
/// and initializes them with the values according to OpenMP standard.
///
/// \param D Directive (possibly) with the 'linear' clause.
- void EmitOMPLinearClauseInit(const OMPLoopDirective &D);
+ /// \return true if at least one linear variable is found that should be
+ /// initialized with the value of the original variable, false otherwise.
+ bool EmitOMPLinearClauseInit(const OMPLoopDirective &D);
typedef const llvm::function_ref<void(CodeGenFunction & /*CGF*/,
llvm::Value * /*OutlinedFn*/,