johannes 02/12/02 17:48:25
Modified: live/gcc3/gcc doloop.c
Log:
Roll in FSF-approved fix (needed for SPEC to work)
Revision Changes Path
1.10 +17 -14 src/live/gcc3/gcc/doloop.c
Index: doloop.c
===================================================================
RCS file: /cvs/Darwin/src/live/gcc3/gcc/doloop.c,v
retrieving revision 1.9
retrieving revision 1.10
diff -u -r1.9 -r1.10
--- doloop.c 2002/10/24 23:42:54 1.9
+++ doloop.c 2002/12/03 01:48:24 1.10
@@ -599,16 +599,19 @@
If the loop has been unrolled, the full calculation is
- t1 = abs_inc * unroll_number; increment per loop
- n = abs (final - initial) / t1; full loops
- n += (abs (final - initial) % t1) != 0; partial loop
-
- However, in certain cases the unrolled loop will be preconditioned
- by emitting copies of the loop body with conditional branches,
- so that the unrolled loop is always a full loop and thus needs
- no exit tests. In this case we don't want to add the partial
- loop count. As above, when t1 is a power of two we don't need to
- worry about overflow.
+ t1 = abs_inc * unroll_number; increment per loop
+ n = (abs (final - initial) + abs_inc - 1) / t1; full loops
+ n += (abs (final - initial) + abs_inc - 1) % t1) >= abs_inc;
+ partial loop
+ which works out to be equivalent to
+
+ n = (abs (final - initial) + t1 - 1) / t1;
+
+ In the case where the loop was preconditioned, a few iterations
+ may have been executed earlier; but 'initial' was adjusted as they
+ were executed, so we don't need anything special for that case here.
+ As above, when t1 is a power of two we don't need to worry about
+ overflow.
The division and modulo operations can be avoided by requiring
that the increment is a power of 2 (precondition_loop_p enforces
@@ -683,10 +686,10 @@
if (shift_count < 0)
abort ();
- if (!loop_info->preconditioned)
- diff = expand_simple_binop (GET_MODE (diff), PLUS,
- diff, GEN_INT (abs_loop_inc - 1),
- diff, 1, OPTAB_LIB_WIDEN);
+ /* (abs (final - initial) + abs_inc * unroll_number - 1) */
+ diff = expand_simple_binop (GET_MODE (diff), PLUS,
+ diff, GEN_INT (abs_loop_inc - 1),
+ diff, 1, OPTAB_LIB_WIDEN);
/* (abs (final - initial) + abs_inc * unroll_number - 1)
/ (abs_inc * unroll_number) */
