Browse Prior Art Database

Method for Selecting a Local Entry Point

IP.com Disclosure Number: IPCOM000241176D
Publication Date: 2015-Apr-01
Document File: 2 page(s) / 75K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to explicitly select a local entry point in a module such that a call to a function in the same module may perform a call to the local entry point.

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Method for Selecting a Local Entry Point

In order to compile applications, architecture application interfaces usually specify a data dictionary (i.e. Global Offset Table (GOT)) which must be available in every

function. These GOTs are shared at the module level; each file shares a GOT. However, each function in a module can be called from within this module and from outside this module; therefore, each function needs to initialize the GOT anew.

When a GOT is initailized, all global data references are dependent on that GOT (typically R12 on z), delaying execution of a function. Because a function may be called from within the same module or outside the module, a function must always initialize the GOT.

Figure 1: z/ABI

The novel contribution is a method to explicitly select a local entry point in a module such that a call to a function in the same module may perform a call to the local entry point: BRASL r14, myfunc@localentry. The method comprises:


• A local entry point corresponding to an accelerated entry

• Means to designate the local entry point location for a symbol • Means to select the local entry point of a symbol - Means to select in assembly source code - Means to select in object code
• Means to resolve reference in conjunction with linking a file

The @localentry specifier indicates selecting a local entry point that bypasses a GOT initialization, thereby making all GOT-relative instructions immediately available to execute.

The method also pr...