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Decoding-and-spec-utils

Rip-guard-okp

Size constraints on a memory address of some instruction byte

Signature
(rip-guard-okp proc-mode rip) → *

This function specifies the maximum size of a memory address that points to some instruction byte in a certain mode of operation. We usually use this function to specify the guard on start-rip or temp-rip --- that way, we can put in suitable type declarations in our specification functions.

This function doesn't really specify whether a memory address that points to some instruction byte is valid or not --- that notion is much more complicated; see canonical-address-p, ea-to-la, and instruction-pointer-operations for details.

Definitions and Theorems

Function: rip-guard-okp

(defun rip-guard-okp (proc-mode rip)
  (declare (type (integer 0 4) proc-mode)
           (type (signed-byte 48) rip))
  (let ((__function__ 'rip-guard-okp))
    (declare (ignorable __function__))
    (if (equal proc-mode 0)
        (signed-byte-p 48 rip)
      (unsigned-byte-p 32 rip))))

Theorem: rip-guard-okp-equiv-for-non-64-bit-modes

(defthm rip-guard-okp-equiv-for-non-64-bit-modes
  (implies (and (rip-guard-okp proc-mode-1 rip)
                (not (equal proc-mode-1 0))
                (not (equal proc-mode-2 0)))
           (rip-guard-okp proc-mode-2 rip)))

Theorem: rip-guard-okp-for-64-bit-modep

(defthm rip-guard-okp-for-64-bit-modep
  (equal (rip-guard-okp 0 rip)
         (signed-byte-p 48 rip)))

Theorem: rip-guard-okp-for-compatibility-mode

(defthm rip-guard-okp-for-compatibility-mode
  (equal (rip-guard-okp 1 rip)
         (unsigned-byte-p 32 rip)))