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Next, up to 63 word arguments may be placed on the stack. The caller then adds the number of arguments to the MARK opcode and pushes that result on the stack. The value of SP is copied to R5. Finally, a JSR PC,address is executed to call the subroutine. After executing its code, the subroutine terminates with an RTS R5. This loads the value in ...
An indirect branch (also known as a computed jump, indirect jump and register-indirect jump) is a type of program control instruction present in some machine language instruction sets. Rather than specifying the address of the next instruction to execute , as in a direct branch , the argument specifies where the address is located.
jsr † a8 1010 1000 2: branchbyte1, branchbyte2 → address jump to subroutine at branchoffset (signed short constructed from unsigned bytes branchbyte1 << 8 | branchbyte2) and place the return address on the stack jsr_w † c9 1100 1001 4: branchbyte1, branchbyte2, branchbyte3, branchbyte4 → address
The function pointer is then simply the address of the trampoline. This avoids having to use "fat" function pointers for nested functions which carry both the code address and the static link. [8] [9] [10] This, however, conflicts with the desire to make the stack non-executable for security reasons.
Examples of, and arguments for, Jump Tables via Function Pointer Arrays in C/C++; Example code generated by 'Switch/Case' branch table in C, versus IF/ELSE. Example code generated for array indexing if structure size is divisible by powers of 2 or otherwise. "Arrays of Pointers to Functions" by Nigel Jones
When executing JSR (jump to subroutine) and RTS (return from subroutine) instructions, the return address pushed to the stack by JSR is that of the last byte of the JSR operand (that is, the most significant byte of the subroutine address), rather than the address of the following instruction.
So-called "subroutine-threaded code" (also "call-threaded code") consists of a series of machine-language "call" instructions (or addresses of functions to "call", as opposed to direct threading's use of "jump"). Early compilers for ALGOL, Fortran, Cobol and some Forth systems often produced subroutine-threaded code. The code in many of these ...
The generated code thus needs to make sure that the call frame for A is properly set up before jumping to the tail-called subroutine. For instance, on platforms where the call stack does not just contain the return address , but also the parameters for the subroutine, the compiler may need to emit instructions to adjust the call stack.