Fix bugs that showed up building Spec on ppc darwin.

From-SVN: r58800

1 files changed, 16 insertions, 13 deletions

diff --git a/gcc/doloop.c b/gcc/doloop.c
index 1f7d47a..67b742c 100644
--- a/gcc/doloop.c
+++ b/gcc/doloop.c
@@ -599,16 +599,19 @@ doloop_modify_runtime (loop, iterations_max,
 
      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
+       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
 
-     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.
+       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 @@ doloop_modify_runtime (loop, iterations_max,
       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)  */