1.0.10.28: export semaphore interface

[sbcl.git] / OPTIMIZATIONS

diff --git a/OPTIMIZATIONS b/OPTIMIZATIONS
index d234ce3..0308f85 100644 (file)
--- a/OPTIMIZATIONS
+++ b/OPTIMIZATIONS
@@ -162,15 +162,6 @@ through TYPEP UNBOXED-ARRAY, within the compiler itself.
 rather than either constant-folding or manipulating NIL-VALUE or
 NULL-TN directly.
 --------------------------------------------------------------------------------
 rather than either constant-folding or manipulating NIL-VALUE or
 NULL-TN directly.
 --------------------------------------------------------------------------------

-#19
-  (let ((dx (if (foo)
-                (list x)
-                (list y z))))
-    (declare (dynamic-extent dx))
-    ...)
-
-DX is not allocated on stack.
---------------------------------------------------------------------------------

 #20
 (defun-with-dx foo (x)
   (flet ((make (x)
 #20
 (defun-with-dx foo (x)
   (flet ((make (x)

@@ -185,14 +176,6 @@ DX is not allocated on stack.
 Result of MAKE is not stack allocated, which means that
 stack-allocation of structures is impossible.
 --------------------------------------------------------------------------------
 Result of MAKE is not stack allocated, which means that
 stack-allocation of structures is impossible.
 --------------------------------------------------------------------------------

-#21
-(defun-with-dx foo ()
-  (let ((dx (list (list 1 2) (list 3 4))))
-    (declare (dynamic-extent dx))
-    ...))
-
-External list in DX is allocated on stack, but internal are not.
---------------------------------------------------------------------------------

 #22
 IR2 does not perform unused code flushing.
 --------------------------------------------------------------------------------
 #22
 IR2 does not perform unused code flushing.
 --------------------------------------------------------------------------------

@@ -224,6 +207,12 @@ Initialization of stack-allocated arrays is inefficient: we always
 fill the vector with zeroes, even when it is not needed (as for
 platforms with conservative GC or for arrays of unboxed objectes) and
 is performed later explicitely.
 fill the vector with zeroes, even when it is not needed (as for
 platforms with conservative GC or for arrays of unboxed objectes) and
 is performed later explicitely.

+
+(This is harder than it might look at first glance, as MAKE-ARRAY is smart
+enough to eliminate something like ':initial-element 0'.  Such an optimization
+is valid if the vector is being allocated in the heap, but not if it is being
+allocated on the stack.  You could remove this optimization, but that makes
+the heap-allocated case somewhat slower...)

 --------------------------------------------------------------------------------
 #28
 a. Accessing raw slots in structure instances is more inefficient than
 --------------------------------------------------------------------------------
 #28
 a. Accessing raw slots in structure instances is more inefficient than

@@ -405,8 +394,25 @@ all three comparisons or b) eliminated the necessity of the MOV(s)
 altogether.  The former option is probably easier than the latter.
 
 --------------------------------------------------------------------------------
 altogether.  The former option is probably easier than the latter.
 
 --------------------------------------------------------------------------------

-#37
+#38
+
+(setf (subseq s1 start1 end1) (subseq s2 start2 end1))
+
+could be transformed into
+
+(let ((#:s2 s2)
+      (#:start2 start2)
+      (#:end2 end2))
+ (replace s1 #:s2 :start1 start1 :end1 end1 :start2 #:start2 :end2 #:end2))
+
+when the return value is unused, avoiding the need to cons up the new sequence.
+
+--------------------------------------------------------------------------------
+#39
+
+(let ((*foo* 42)) ...)

 
 

-Dynamic extent allocation doesn't currently work for one-element lists,
-since there's a source transform from (LIST X) to (CONS X NIL).
+currently compiles to code that ensures the TLS index at runtime, which
+is both a decently large chunk of code and unnecessary, as we could ensure
+the TLS index at load-time as well.