Oracle Corporation
Conditional branch frame barrier

Abstract:

Establishing a conditional branch frame barrier is described. A conditional branch in a function epilogue is used to provide frame-specific control. The conditional branch evaluates a return condition to determine whether to return from a callee function to a calling function, or to execute a slow path instead. The return condition is evaluated based on a thread local value. The thread local value is set such that returns to potentially unsafe frames in a call stack are prohibited. The prohibition to return to a potentially unsafe frame may be referred to as a "frame barrier." Additionally, the thread local value may be used to establish safepointing and/or thread local handshakes, both after execution of a function body and after execution of a loop body.