[OPENMP] Codegen for 'if' clause in 'parallel' directive.

Adds codegen for 'if' clause. Currently only for 'if' clause used with the 'parallel' directive.
If condition evaluates to true, the code executes parallel version of the code by calling __kmpc_fork_call(loc, 1, microtask, captured_struct/*context*/), where loc - debug location, 1 - number of additional parameters after "microtask" argument, microtask - is outlined finction for the code associated with the 'parallel' directive, captured_struct - list of variables captured in this outlined function.
If condition evaluates to false, the code executes serial version of the code by executing the following code:

global_thread_id.addr = alloca i32
store i32 global_thread_id, global_thread_id.addr
zero.addr = alloca i32
store i32 0, zero.addr
kmpc_serialized_parallel(loc, global_thread_id);
microtask(global_thread_id.addr, zero.addr, captured_struct/*context*/);
kmpc_end_serialized_parallel(loc, global_thread_id);

Where loc - debug location, global_thread_id - global thread id, returned by __kmpc_global_thread_num() call or passed as a first parameter in microtask() call, global_thread_id.addr - address of the variable, where stored global_thread_id value, zero.addr - implicit bound thread id (should be set to 0 for serial call), microtask() and captured_struct are the same as in parallel call.

Also this patch checks if the condition is constant and if it is constant it evaluates its value and then generates either parallel version of the code (if the condition evaluates to true), or the serial version of the code (if the condition evaluates to false).
Differential Revision: http://reviews.llvm.org/D4716

llvm-svn: 219597

1 files changed, 24 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.h b/clang/lib/CodeGen/CGOpenMPRuntime.h
index ce822ea7d1b..04378821d7a 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntime.h
+++ b/clang/lib/CodeGen/CGOpenMPRuntime.h
@@ -74,7 +74,13 @@ public:
     // kmp_critical_name *crit);
     OMPRTL__kmpc_end_critical,
     // Call to void __kmpc_barrier(ident_t *loc, kmp_int32 global_tid);
-    OMPRTL__kmpc_barrier
+    OMPRTL__kmpc_barrier,
+    // Call to void __kmpc_serialized_parallel(ident_t *loc, kmp_int32
+    // global_tid);
+    OMPRTL__kmpc_serialized_parallel,
+    // Call to void __kmpc_end_serialized_parallel(ident_t *loc, kmp_int32
+    // global_tid);
+    OMPRTL__kmpc_end_serialized_parallel
   };
 
 private:
@@ -156,10 +162,10 @@ private:
   EmitOpenMPUpdateLocation(CodeGenFunction &CGF, SourceLocation Loc,
                            OpenMPLocationFlags Flags = OMP_IDENT_KMPC);
 
-  /// \brief Returns pointer to ident_t type;
+  /// \brief Returns pointer to ident_t type.
   llvm::Type *getIdentTyPointerTy();
 
-  /// \brief Returns pointer to kmpc_micro type;
+  /// \brief Returns pointer to kmpc_micro type.
   llvm::Type *getKmpc_MicroPointerTy();
 
   /// \brief Returns specified OpenMP runtime function.
@@ -167,6 +173,11 @@ private:
   /// \return Specified function.
   llvm::Constant *CreateRuntimeFunction(OpenMPRTLFunction Function);
 
+  /// \brief Emits address of the word in a memory where current thread id is
+  /// stored.
+  virtual llvm::Value *EmitThreadIDAddress(CodeGenFunction &CGF,
+                                           SourceLocation Loc);
+
   /// \brief Gets thread id value for the current thread.
   ///
   llvm::Value *GetOpenMPThreadID(CodeGenFunction &CGF, SourceLocation Loc);
@@ -201,6 +212,16 @@ public:
                                    llvm::Value *OutlinedFn,
                                    llvm::Value *CapturedStruct);
 
+  /// \brief Emits code for serial call of the \a OutlinedFn with variables
+  /// captured in a record which address is stored in \a CapturedStruct.
+  /// \param OutlinedFn Outlined function to be run in serial mode.
+  /// \param CapturedStruct A pointer to the record with the references to
+  /// variables used in \a OutlinedFn function.
+  ///
+  virtual void EmitOMPSerialCall(CodeGenFunction &CGF, SourceLocation Loc,
+                                 llvm::Value *OutlinedFn,
+                                 llvm::Value *CapturedStruct);
+
   /// \brief Returns corresponding lock object for the specified critical region
   /// name. If the lock object does not exist it is created, otherwise the
   /// reference to the existing copy is returned.