src/compiler/policies.lisp

   1 ;;;; aimed optimization qualities
   2
   3 ;;;; This software is part of the SBCL system. See the README file for
   4 ;;;; more information.
   5 ;;;;
   6 ;;;; This software is derived from the CMU CL system, which was
   7 ;;;; written at Carnegie Mellon University and released into the
   8 ;;;; public domain. The software is in the public domain and is
   9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  10 ;;;; files for more information.
  11
  12 (in-package "SB!C")
  13
  14 (define-optimization-quality type-check
  15     ;; FIXME: grepping the tree for "policy.*safety" yields some
  16     ;; places which might want to use this instead -- or
  17     ;; some other derived policy.
  18     (cond ((= safety 0) 0)
  19           ((and (< safety 2) (< safety speed)) 2)
  20           (t 3))
  21   ("no" "maybe" "weak" "full")
  22   "Control the way to perform runtime type checking:
  23 0: declared types are simply trusted; no runtime checks are performed;
  24 2: fast checks are performed: declared types are weakened to
  25    FIXNUM/SINGLE-FLOAT/FLOAT/NUMBER/structure/specialized array etc.;
  26 3: declared types are fully checked (several exceptions exist;
  27    see \"SBCL User Manual\", Compiler->Handling of Types->
  28    Implementation Limitations for details).")
  29
  30 (define-optimization-quality check-tag-existence
  31     (cond ((= safety 0) 0)
  32           (t 3))
  33   ("no" "maybe" "yes" "yes")
  34   "Control whether GO and RETURN-FROM check liveness of the destination tag.
  35 Enabling this option can increase heap consing of closures.")
  36
  37 (define-optimization-quality let-conversion
  38     (if (<= debug speed) 3 0)
  39   ("off" "maybe" "on" "on")
  40   "Control inline-substitution of used-once local functions.")
  41
  42 (define-optimization-quality verify-arg-count
  43     (if (zerop safety) 0 3)
  44   ("no" "maybe" "yes" "yes"))
  45
  46 (define-optimization-quality merge-tail-calls
  47     (if (or (> space debug)
  48             (> speed debug))
  49         3
  50         0)
  51   ("no" "maybe" "yes" "yes")
  52   "Control whether tail-calls should reuse caller stack frame.
  53 Enabling this option make functions use less stack space, and make
  54 tail-recursive functions execute in constant stack, but debugging
  55 become harder, because backtraces show only part of function call
  56 sequence.
  57
  58 This options has no effect when INSERT-DEBUG-CATCH is set.")
  59
  60 (define-optimization-quality insert-debug-catch
  61     (if (> debug (max speed space))
  62         3
  63         0)
  64   ("no" "maybe" "yes" "yes")
  65   "Enable possibility of returning from stack frames with the debugger.
  66
  67 Enabling this option effectively disables MERGE-TAIL-CALLS.")
  68
  69 (define-optimization-quality recognize-self-calls
  70     (if (> (max speed space) debug)
  71         3
  72         0)
  73   ("no" "maybe" "yes" "yes")
  74   "When enabled, reference to a function FOO inside the body of (DEFUN
  75 FOO ...) is considered to be the reference to the function being
  76 defined. Calls to FOO are compiled as local. This allows better
  77 optimization and type checking, but TRACE will not show recursive
  78 calls. If the function object is bound to another name BAR, and FOO is
  79 bound to another function, calls to FOO inside BAR will remain to be
  80 recursive.
  81
  82 When disabled, internal references to a function FOO will be
  83 considered ti be a call of a function, bound to the symbol at
  84 run-time, which is less efficient. TRACE will show recursive calls. In
  85 case of renaming described above, calls to FOO will not be recursive
  86 and will refer to the new function, bound to FOO.")
  87
  88 (define-optimization-quality stack-allocate-dynamic-extent
  89     (if (and (> (max speed space) (max debug safety))
  90              (< safety 3))
  91         3
  92         0)
  93   ("no" "maybe" "yes" "yes")
  94   "Control whether allocate objects, declared DYNAMIC-EXTENT, on
  95 stack.")
  96
  97 (define-optimization-quality stack-allocate-vector
  98     (cond ((= stack-allocate-dynamic-extent 0) 0)
  99           ((= safety 0) 3)
 100           (t 2))
 101   ("no" "maybe" "one page" "yes")
 102   "Control what vectors, declared DYNAMIC-EXTENT, are allocated on stack:
 103 0: no vectors are allocated on stack;
 104 2: only short vectors (compiler knows them to fit on one page);
 105 3: every.
 106
 107 This option has an effect only when STACK-ALLOCATE-DYNAMIC-EXTENT is
 108 set.")
 109
 110 (define-optimization-quality float-accuracy
 111     3
 112   ("degraded" "full" "full" "full"))
 113
 114 (define-optimization-quality insert-step-conditions
 115     (if (> debug (max speed space compilation-speed))
 116         debug
 117         0)
 118   ("no" "no" "partial" "full")
 119   "Control instrumentation of code, enabling single-stepping through
 120 it in the debugger.
 121
 122 This option has no effect without COMPUTE-DEBUG-FUN.")
 123
 124 (define-optimization-quality compute-debug-fun
 125     debug
 126   ("no" "minimal" "yes" "yes"))
 127
 128 (define-optimization-quality preserve-single-use-debug-variables
 129     (if (and (>= debug 2)
 130              (< speed 3))
 131         3
 132         0)
 133   ("no" "no" "no" "yes")
 134   "When disabled, LET variable, which is never set and is referenced
 135 exactly once, is eliminated and the reference is substituted with the
 136 initial value. This allows better type inference and some algebraic
 137 optimizations.
 138
 139 When enabled, the variable is preserved and can be seen in the
 140 debugger.")
 141
 142 (define-optimization-quality insert-array-bounds-checks
 143     (if (= safety 0) 0 3)
 144   ("no" "yes" "yes" "yes"))
 145
 146 (define-optimization-quality store-xref-data
 147     (if (= space 3)
 148         0
 149         3)
 150   ("no" "yes" "yes" "yes"))
 151
 152 (define-optimization-quality store-coverage-data
 153     0
 154   ("no" "no" "yes" "yes"))