International Business Machines Corporation

Ulrich Weigand

Michael K Gschwind

Ronald Ian McIntosh

Brian King Flachs

William Jon Schmidt

Carsten Otte

Ayal Zaks

Alan David Modra

Charles Ray Johns

Mark Richard Nutter

Alexandre E Eichenberger

John Kevin Patrick O'Brien

Martin Schwidefsky

Christian Borntraeger

Wolfgang Reichert

Ira Rosen

Archana Ravindar

Jochen Roehrig

Dorit Nuzman

Srinivas R Vaidya

Christian Ehrhardt

Frederik J Hartmann

Revital Erez

A method and associated computer program product are disclosed for generating an object file for subsequent linking by a linker. The method comprises inserting at least one save instruction before a function call instruction and at least one restore instruction after the function call instruction, the at least one save instruction and the least one restore instruction corresponding to one or more call-clobbered registers. The method further comprises generating a first list of registers that are referenced by the function. The function call instruction includes a first annotation referencing the restore instruction, and the restore instruction includes a second annotation referencing the save instruction. The first and second annotations configure the linker to determine whether to eliminate the save instruction and the restore instruction corresponding to at least one of the one or more call-clobbered registers.

Reduced save and restore instructions for call-clobbered registers

A compiler and linker include multiple addressing mode resolvers that generate code to resolve a plurality of function calls that use different addressing modes. A first addressing mode is defined where a first address for first data is specified as an offset from a base pointer. A second, relative addressing mode is defined where a second address for second data is specified as an offset from an address of an instruction that references the second data. The generated code assures correct operation when functions with different addressing modes are included in the computer program. The generated code preserves a base pointer when executing a function that uses relative addressing, when needed. The compiler inserts one or more relocation markers that trigger certain functions in the linker. A linker resolves the relocation markers inserted by the compiler, and generates code, when needed, that handles a mismatch between addressing modes.

Generating code for function calls that use multiple addressing modes

A method and associated computer program product are disclosed for generating an executable file from an object file, the object file being associated with an architecture having a predefined calling convention designating one or more call-clobbered registers. The method comprises identifying, from a first annotation included in the object file with a function call instruction, at least one restore instruction that follows the function call instruction, the function call instruction associated with a predefined function of the object file. The at least one restore instruction corresponds to at least one of the one or more call-clobbered registers. The method further comprises determining, based on at least a first list of registers that are referenced by the predefined function, the first list being included in the object file, whether to eliminate the at least one restore instruction.

Embodiments relate to using a local entry point with an indirect call function. More specifically, a linker is provided to generate at application modules that at least partially defines an indirect function call configuration. The linker loads a first address of a function by using a first symbolic reference, and determines that the function pointer value of the first symbolic reference is solely used to perform indirect calls in the same application module, e.g. local-use-only. The linker indicates that the first symbolic reference can be resolved using the local entry point associated with the function, and performs that indirect function call exclusively through the first symbolic reference, thereby reducing execution of operations.

Linking optimized entry points for local-use-only function pointers

A translation component, such as a compiler, recognizes comments of a program and uses those comments to provide optimization recommendations or to generate optimized code to improve processing within a computing environment. The comments are translated into structures recognizable by translation phases to generate more efficient code or pragmas to improve performance.

Using comments of a program to provide optimizations

Embodiments relate to optimizing an indirect call function. A compiler is provided to identify potential target functions and indicate the potential target functions in the program code. Additionally, the compiler determines and indicates in the program code that the function pointer value resulting from a non-call reference of a function symbol is solely used to perform indirect calls in the same module. A linker can read the indication the compiler made in the program code and optimize the indirect call function.

Executing optimized local entry points and function call sites

Embodiments relate to using a local entry point with an indirect call function. A compiler is provided to determine and indicate in the program code that the function pointer value resulting from a non-call reference of a function symbol is solely used to perform indirect calls in the same module, e.g. local-use-only. The compiler loads an address of a function through use of a symbolic reference. When the compiler determines that the value employed by the symbolic reference is used exclusively to perform an indirect function call, the compiler proceeds to resolve a local entry point address of the function, thereby reducing a quantity of operations to be executed.

Compiling optimized entry points for local-use-only function pointers

Embodiments relate to using a local entry point with an indirect call function. More specifically, an indirect call function configuration comprises a first application module having a target function of the indirect function call, a second application module with a symbolic reference to the target function of the indirect function call, and a third application module to originate an indirect function call. A compiler determines and indicates, in the program code, that the function pointer value resulting from a non-call reference of a function symbol is solely used to perform indirect calls in the same module, e.g. local-use-only. A linker or loader can read the indication the compiler made in the program code. The linker or loader use the local entry point associated with the target function if the target function is defined in the same module as the reference and is local-use-only.

Loading optimized local entry points for local-use-only function pointers

Embodiments relate to optimizing an indirect call function. More specifically, an indirect call function configuration comprises a first application module having a target function of the indirect function call, a second application module with a symbolic reference to the target function of the indirect function call, and a third application module to originate an indirect function call. A compiler is provided to identify potential target functions and indicate the potential target functions in the program code. Additionally, the compiler determines and indicates in the program code that the function pointer value resulting from a non-call reference of a function symbol is solely used to perform indirect calls in the same module. A linker can read the indication the compiler made in the program code and optimize the indirect call function.

Optimized entry points and local function call tailoring for function pointers

Embodiments relate to optimizing an indirect call function. More specifically, an indirect call function configuration comprises a first application module having a target function of the indirect function call, a second application module with a symbolic reference to the target function of the indirect function call, and a third application module to originate an indirect function call. A compiler identifies potential target functions and indicates the potential target functions in the program code. Additionally, the compiler determines and indicates in the program code that the function pointer value resulting from a non-call reference of a function symbol is solely used to perform indirect calls in the same module. A linker can read the indication the compiler made in the program code and optimize the indirect call function.

Embodiments relate to using a local entry point with an indirect call function. More specifically, an indirect call function configuration comprises a first application module having a target function of the indirect function call, a second application module with a symbolic reference to the target function of the indirect function call, and a third application module to originate an indirect function call. A compiler is provided to identify potential target functions and indicate the potential target functions in the program code. A linker can read the indication the compiler made in the program code. The linker optimizes an indirect call site if the potential target functions are defined in the same module.

Growing community of inventors

Holzgerlingen, Germany

Ulrich Weigand