[OPENMP] Codegen for 'atomic update' construct.

Adds atomic update codegen for the following forms of expressions:

x binop= expr;
x++;
++x;
x--;
--x;
x = x binop expr;
x = expr binop x;
If x and expr are integer and binop is associative or x is a LHS in a RHS of the assignment expression, and atomics are allowed for type of x on the target platform atomicrmw instruction is emitted.
Otherwise compare-and-swap sequence is emitted:

bb:
...
atomic load <x>
cont:
<expected> = phi [ <x>, label %bb ], [ <new_failed>, %cont ]
<desired> = <expected> binop <expr>
<res> = cmpxchg atomic &<x>, desired, expected
<new_failed> = <res>.field1;
br <res>field2, label %exit, label %cont
exit:
...

Differential Revision: http://reviews.llvm.org/D8536

llvm-svn: 233513

1 files changed, 5 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 151eb7e..2473ab6 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -2123,12 +2123,16 @@ public:
   void EmitAtomicStore(RValue rvalue, LValue lvalue, llvm::AtomicOrdering AO,
                        bool IsVolatile, bool isInit);
 
-  std::pair<RValue, RValue> EmitAtomicCompareExchange(
+  std::pair<RValue, llvm::Value *> EmitAtomicCompareExchange(
       LValue Obj, RValue Expected, RValue Desired, SourceLocation Loc,
       llvm::AtomicOrdering Success = llvm::SequentiallyConsistent,
       llvm::AtomicOrdering Failure = llvm::SequentiallyConsistent,
       bool IsWeak = false, AggValueSlot Slot = AggValueSlot::ignored());
 
+  void EmitAtomicUpdate(LValue LVal, llvm::AtomicOrdering AO,
+                        const std::function<RValue(RValue)> &UpdateOp,
+                        bool IsVolatile);
+
   /// EmitToMemory - Change a scalar value from its value
   /// representation to its in-memory representation.
   llvm::Value *EmitToMemory(llvm::Value *Value, QualType Ty);