From da943cec51946f953c4b73ecd1dae9e0778a7a0b Mon Sep 17 00:00:00 2001 From: dick Date: Wed, 22 Jun 1988 17:09:12 +0000 Subject: [PATCH] Initial entry --- util/int/TODO | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 util/int/TODO diff --git a/util/int/TODO b/util/int/TODO new file mode 100644 index 000000000..296727d4b --- /dev/null +++ b/util/int/TODO @@ -0,0 +1,69 @@ +- Reduction of repetetivity in the code +Before making any major changes to the interpreter, it would be good to +implement Model 3 (Intelligent Calls), as described in the interpreter +documentation. This will reduce the bulk of the code considerably, since then +there will be only one routine for each instruction. Now identical changes +have to be made in n places. + + +- Shadow bytes with internal values +The biggest problem with the interpreter is that undefinedness is not +transitive. A warning is given if an undefined value is used, but then the +interpreter goes on to use the (zero) value as if nothing had happened. The +reason is that internal values in the interpreter have no shadow bytes, and +consequently the undefinedness is lost as soon as a value is passed to an +operation. Likewise the type is lost, which makes it impossible to do good +type cheking on pointers. If internal values would have a shadow byte (only +one per values is needed), we could have a shadow bit signifying "derives from +null pointer", which could be checked when the pointer is dereferenced. +Presently only the value of the pointer is checked. + + +- Name generation upon forking. +At present there is an ad-hoc mechanism for generating new file names for +int.log and int.mess and a new variable name for LOG= upon forking. This +mechanism is not well localized and does not generalize immediately to other +file names like int.tally and int.core. Another consequence is that the AT= +facility is presently implemented as a patch. + + +- Integration of memory access +Presently each memory access consists of at least three calls, one to check +the shadow byte, one to store the data and one to rewrite or update the shadow +byte; each of these do the same address evaluations etc. There should +probably be routines for integrated writing and reading of bytes. + + +- Improvements of warnings +Presently warnings are indicated by a single number, in warn.h. This is often +too little information. The warning should be a printf format, and warning() +should accept a variable number of parameters. + + +- There seems to be no way of obtaining the largest possible double +on a machine in a system-independent way (except, perhaps, for including +). For the time being there is a #define MAXDOUBLE in do_fpar.c. + + +- Program to process the int.tally file + + +- Program to process int.core; also, define a more proper format for the +int.core file. + + +- Some esthetic problems + - The system call umount is called unmount on some systems, or + even called differently in different libraries on the same + system. It is not clear to me who is to blame, nor if that + would help. + + + + + +[[ +Proposed code to be generated by mkswitch.c; +type to be had from /ur/em/etc/em_table. +DoXXX[01](par) long par { type arg = (LOG(("@X9 XXX %lt", par)), arg_t(par)); } +]] -- 2.34.1