From 7562df8122d83aa86ddbc2e096a96ef16e85045f Mon Sep 17 00:00:00 2001 From: Nick Clifton Date: Fri, 31 Aug 2007 14:28:38 +0000 Subject: [PATCH] tree-ssa-coalesce.c (compare_pairs): Use the elements as secondary keys in order to obtain a stable sort. * tree-ssa-coalesce.c (compare_pairs): Use the elements as secondary keys in order to obtain a stable sort. From-SVN: r127993 --- gcc/ChangeLog | 5 +++++ gcc/tree-ssa-coalesce.c | 18 ++++++++++++++++-- 2 files changed, 21 insertions(+), 2 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 50832cf78bf..e7d598a7a7f 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2007-08-31 Nick Clifton + + * tree-ssa-coalesce.c (compare_pairs): Use the elements as + secondary keys in order to obtain a stable sort. + 2007-08-31 Nick Clifton PR target/33132 diff --git a/gcc/tree-ssa-coalesce.c b/gcc/tree-ssa-coalesce.c index 1b63635881b..ef1ebcab4a9 100644 --- a/gcc/tree-ssa-coalesce.c +++ b/gcc/tree-ssa-coalesce.c @@ -314,8 +314,22 @@ add_coalesce (coalesce_list_p cl, int p1, int p2, static int compare_pairs (const void *p1, const void *p2) { - return (*(const_coalesce_pair_p const*)p1)->cost - - (*(const_coalesce_pair_p const*)p2)->cost; + const_coalesce_pair_p const * pp1 = p1; + const_coalesce_pair_p const * pp2 = p2; + int result; + + result = (* pp2)->cost - (* pp1)->cost; + /* Since qsort does not guarantee stability we use the elements + as a secondary key. This provides us with independence from + the host's implementation of the sorting algorithm. */ + if (result == 0) + { + result = (* pp2)->first_element - (* pp1)->first_element; + if (result == 0) + result = (* pp2)->second_element - (* pp1)->second_element; + } + + return result; }