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A compiler generates compiled object code from source code of a computer program in a manner that produces efficient object code for a computer with dissimilar register spaces. The technique comprising the steps of (1) generating code that references symbolic registers in which the register class is

A compiler generates compiled object code from source code of a computer program in a manner that produces efficient object code for a computer with dissimilar register spaces. The technique comprising the steps of (1) generating code that references symbolic registers in which the register class is not distinguished, (2) making entries in a table denoting the context in which each symbolic register occurs and constructing an equivalence tree of symbolic registers for move instructions assigned to a same equivalence class, (3) for each equivalence class, forming the logical OR function of register usage information for all symbolic registers in the class, and for each symbolic register that appears in more than one register space context, generating new symbolic register numbers so that there is one number for each register space, and storing the numbers in said table, and (4) if a definition point of a symbolic register is encountered and that symbolic register is used in more than one register space context, inserting code in said program to either do the same operation as is done at the definition point in each register space or move a value in the symbolic register from one space to another. The improvement achieved is in object code space and time of execution.

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In a compiler which generates compiled object code from source code of a computer program, a computer performed method of generating efficient object code for a computer with dissimilar register spaces comprising the steps of: generating by a computer code that references symbolic registers in which

In a compiler which generates compiled object code from source code of a computer program, a computer performed method of generating efficient object code for a computer with dissimilar register spaces comprising the steps of: generating by a computer code that references symbolic registers in which a register class is not distinguished; making entries in a table by the computer denoting a context in which each symbolic register occurs and constructing an equivalence tree of symbolic registers for move instructions assigned to a same equivalence class; for each equivalence class, forming by the computer a logical OR function of register usage information for all symbolic registers in the equivalence class, and for each symbolic register that appears in more than one register space context, generating by the computer new symbolic register numbers so that there is one number for each register space, and storing the new symbolic register numbers in said table; and if a definition point of a symbolic register is encountered and that symbolic register is used in more than one register space context, inserting by the computer code in said program to either do a same operation as is done at the definition point in each register space or move a value in the symbolic register from one space to another.