Object Code Accelerator Manual

Preparing Programs for Acceleration

Object Code Accelerator Manual—528144-003

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C Function Prototypes

The C/C++ compiler uses function prototypes to determine the return value size for

calls to routines declared in separate modules or to routines declared later in the same

module. If you do not specify a function protoype, the C/C++ compiler assumes the

function returns an INT value. On the TNS architecture, the object code runs correctly

if either the function returns an INT value or no value. OCA generates code that

assumes that the function returns an INT value. In most cases, OCA can process

object files compiled without C/C++ function prototypes, but the resulting accelerated

object code is often inefficient and makes numerous transitions into executing TNS

code. If possible, use C/C++ function prototypes for all of your C/C++ routines.

Binder and Inspect Symbols Regions

OCA uses information from the Binder region and the Inspect symbols region of an

object file to help perform control-flow analysis and optimizations. It can process most

files without this information, but the resulting accelerated object code is often

inefficient and makes numerous transitions into executing TNS code. If possible,

accelerate object files that contain the Binder and Inspect symbols regions. After

accelerating a program, you can strip the symbols region from it without impacting

performance.

Variances in Accelerated Code

This section describes the variances between TNS and TNS/E systems that apply to

accelerated object code. Check your programs for variances in:

•

Trap handlers that use the ENV register

•

Passing parameters in registers

•

The arithmetic left-shift sign bit

•

Non-standard procedure call or return RP values

•

The relationship between the global and local data blocks

•

Procedure name conflicts

Trap Handlers Using the ENV Registers

The value of ENV.RP is undefined for accelerated programs. For compatibility with

TNS processors, your trap handlers must set ENV.RP to 7 if they resume execution

from a trap to a global restart point.

The condition codes N, Z, and K are undefined for traps that occur when executing