Method and system for type demotion of expressions and variables by bitwise constant propagation

A computer-readable medium having stored thereon a plurality of instructions, said plurality of instructions when executed by a computer, cause said computer to perform:

• analyzing code using bitwise constant propagation by a language implementation system to determine a backward value for each alias in the code that reflects any reference to the alias occurring outside of and following the code under analysis;
• determining whether an operation therein on a larger data type may be replaced with an operation on a smaller data type having a reduced precision, wherein the determining is based on the backward values of each alias in the analyzed code;
• and
• replacing the operation on the larger data type with the operation on the smaller data type if so determined.

A system, comprising:

• a processor;
• memory connected to the processor to store instructions for type demotion of expressions and variables by bitwise constant propagation, the instructions to be executed by the processor;
• storage connected to the processor to store a software code having a plurality of separately compilable routines;
• wherein the processor to execute the instructions on the code to:
• analyze code using bitwise constant propagation by a language implementation system to determine a backward value for each alias in the code that reflects any reference to the alias occurring outside of and following the code under analysis;
• determine whether an operation on a larger data type may be replaced with an operation therein on a smaller data type having a reduced precision, wherein the determining is based on the backward values of each alias in the analyzed code;
• and
• replace the operation on the larger data type with the operation on the smaller data type if so determined.

A system, comprising:

• means for analyzing code using bitwise constant propagation by a language implementation system to determine a backward value for each alias in the code that reflects any reference to the alias occurring outside of and following the code under analysis;
• means for determining whether an operation therein on a larger data type may be replaced with an operation on a smaller data type having a reduced precision, wherein the determining is based on the backward values of each alias in the analyzed code;
• and
• means for replacing the operation on the larger data type with the operation on the smaller data type if so determined.