Minor tweaks to code computing modular multiplicative inverse

This removes the last parameter of choose_multiplier, which is unused, adds
another assertion and more details to the description and various comments.
Likewise to the closely related invert_mod2n, except for the last parameter.

[changelog]
	* expmed.h (choose_multiplier): Tweak description and remove last
	parameter.
	* expmed.cc (choose_multiplier): Likewise.  Add assertion for the
	third parameter and adds details to various comments.
	(invert_mod2n): Tweak description and add assertion for the first
	parameter.
	(expand_divmod): Adjust calls to choose_multiplier.
	* tree-vect-generic.cc (expand_vector_divmod): Likewise.
	* tree-vect-patterns.cc (vect_recog_divmod_pattern): Likewise.

1 files changed, 7 insertions, 7 deletions

diff --git a/gcc/tree-vect-patterns.cc b/gcc/tree-vect-patterns.cc
index 87c2acf..8e8de5e 100644
--- a/gcc/tree-vect-patterns.cc
+++ b/gcc/tree-vect-patterns.cc
@@ -4535,7 +4535,7 @@ vect_recog_divmod_pattern (vec_info *vinfo,
   enum tree_code rhs_code;
   optab optab;
   tree q, cst;
-  int dummy_int, prec;
+  int prec;
 
   if (!is_gimple_assign (last_stmt))
     return NULL;
@@ -4795,17 +4795,17 @@ vect_recog_divmod_pattern (vec_info *vinfo,
 	/* FIXME: Can transform this into oprnd0 >= oprnd1 ? 1 : 0.  */
 	return NULL;
 
-      /* Find a suitable multiplier and right shift count
-	 instead of multiplying with D.  */
-      mh = choose_multiplier (d, prec, prec, &ml, &post_shift, &dummy_int);
+      /* Find a suitable multiplier and right shift count instead of
+	 directly dividing by D.  */
+      mh = choose_multiplier (d, prec, prec, &ml, &post_shift);
 
-      /* If the suggested multiplier is more than SIZE bits, we can do better
+      /* If the suggested multiplier is more than PREC bits, we can do better
 	 for even divisors, using an initial right shift.  */
       if (mh != 0 && (d & 1) == 0)
 	{
 	  pre_shift = ctz_or_zero (d);
 	  mh = choose_multiplier (d >> pre_shift, prec, prec - pre_shift,
-				  &ml, &post_shift, &dummy_int);
+				  &ml, &post_shift);
 	  gcc_assert (!mh);
 	}
       else
@@ -4924,7 +4924,7 @@ vect_recog_divmod_pattern (vec_info *vinfo,
 	/* This case is not handled correctly below.  */
 	return NULL;
 
-      choose_multiplier (abs_d, prec, prec - 1, &ml, &post_shift, &dummy_int);
+      choose_multiplier (abs_d, prec, prec - 1, &ml, &post_shift);
       if (ml >= HOST_WIDE_INT_1U << (prec - 1))
 	{
 	  add = true;