From e98e35ee5b21dcba6a3548655565391e45f826cb Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Mon, 14 Oct 2019 13:01:16 -0400
Subject: [PATCH] Added `-no-call-history` flag

Allow for faster executables at the expense of call history.
---
 CHANGELOG.md            |  4 ++++
 cyclone.scm             | 13 ++++++++++++-
 scheme/cyclone/cgen.sld |  8 ++++++--
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e2ab97e8..28a7c220 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,10 @@
 TODO: mention cyclone-winds even though not part of this official release
 https://github.com/cyclone-scheme/cyclone-winds
 
+Features
+
+ - Added the `-no-call-history` flag to potentially allow for faster executables at the expense of call history.
+
 Bug Fixes
 
 - Fix `read-u8`, `peek-u8`, and `write-u8` to work with integers (bytes) instead of characters.
diff --git a/cyclone.scm b/cyclone.scm
index dfb62866..6144424d 100644
--- a/cyclone.scm
+++ b/cyclone.scm
@@ -25,6 +25,7 @@
 
 (define *optimization-level* 2) ;; Default level
 (define *optimize:memoize-pure-functions* #t) ;; Memoize pure funcs by default
+(define *cgen:track-call-history* #t)
 
 ; Placeholder for future enhancement to show elapsed time by phase:
 (define *start* (current-second))
@@ -463,6 +464,8 @@
           ((eq? flag 'memoize-pure-functions) 
            (and program? ;; Only for programs, because SRFI 69 becomes a new dep
                 *optimize:memoize-pure-functions*))
+          ((eq? flag 'track-call-history)
+           *cgen:track-call-history*)
           (else #f)))
 
       (when (> *optimization-level* 0)
@@ -553,7 +556,8 @@
                     module-globals
                     c-headers
                     lib-deps
-                    src-file) 
+                    src-file
+                    flag-set?) 
       (return '())))) ;; No codes to return
 
 ;; Read top-level imports from a program and return a cons of:
@@ -769,6 +773,8 @@
       (set! *optimize:memoize-pure-functions* #t))
   (if (member "-no-memoization-optimizations" args)
       (set! *optimize:memoize-pure-functions* #f))
+  (if (member "-no-call-history" args)
+      (set! *cgen:track-call-history* #f))
   ;; TODO: place more optimization reading here as necessary
   ;; End optimizations
   (if (member "-t" args)
@@ -811,6 +817,11 @@ Optimization options:
                                 where possible (enabled by default).
  -no-memoization-optimizations  Disable the above memoization optimization.
 
+Debug options
+
+ -no-call-history     Do not track call history in the compiled code. This 
+                      allows for a faster runtime at the cost of having 
+                      no call history in the event of an exception.
 ")
      (newline))
     ((member "-v" args)
diff --git a/scheme/cyclone/cgen.sld b/scheme/cyclone/cgen.sld
index e93fc08e..9f8f42d8 100644
--- a/scheme/cyclone/cgen.sld
+++ b/scheme/cyclone/cgen.sld
@@ -40,6 +40,7 @@
     st:->var)
   (begin
 
+(define *cgen:track-call-history* #t)
 (define *optimize-well-known-lambdas* #f)
 
 (define (emit line)
@@ -263,7 +264,8 @@
 
 (define (st:->code trace)
   (if (or (not (pair? trace))
-          (null? (cdr trace)))
+          (null? (cdr trace))
+          (not *cgen:track-call-history*))
     ""
     (string-append 
       "Cyc_st_add(data, \""
@@ -1848,8 +1850,10 @@
                       globals
                       c-headers
                       required-libs
-                      src-file)
+                      src-file
+                      flag-set?)
   (set! *global-syms* (append globals (lib:idb:ids import-db)))
+  (set! *cgen:track-call-history*  (flag-set? 'track-call-history))
   (set! num-lambdas (+ (adb:max-lambda-id) 1))
   (set! cgen:mangle-global
     (lambda (ident)