Raymond Toy pushed to branch issue-97-define-ud2-inst at cmucl / cmucl

Commits:

• ae94d97a
  by Raymond Toy at 2021-04-13T22:34:46-07:00

  Update the int instruction to disassemble int3
  
  The int instruction would accept a code of 3 but would produce an int3
  instruction.  However, the disassembly of this wasn't working since
  the printer expected the opcode to be #b11001101 which didn't match
  what was generated.  Hence, add a new printer to print int3 as "int
  3".
  
  Tested this by setting a breakpoint and disassembling the function to
  see that the breakpoint is printed as "int 3" instead ".byte #xcc".
  
  (Should we really make a separate int3 instruction?)
  

1 changed file:

• src/compiler/x86/insts.lisp

Changes:

 			  (ldb (byte 3 3) code)

 			  (ldb (byte 3 0) code))))

+;; Handles both int and int3.  To get int3 you have to say (inst int

+;; 3).  But int3 should not be used in Lisp code.  This is mainly so

+;; that int3 gets disassembled correctly if a breakpoint has been set

+;; in Lisp code.  (But in general the disassembly will be messed up

+;; because the following byte will in general be the second byte of

+;; some instruction, and not the first byte of an instruction.)

 (define-instruction int (segment number)

   (:declare (type (unsigned-byte 8) number))

   (:printer byte-imm ((op #b11001101)))

+  (:printer byte ((op #b11001100))

+	    `(:name :tab 3))

   (:emitter

    (etypecase number

      ((member 3)