* builtins.c (expand_builtin_mathfn): Make sure not to expand the

	argument more than once.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@30963 138bc75d-0d04-0410-961f-82ee72b054a4

2 files changed, 13 insertions, 1 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5e8cfedadd0..0462e45f374 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+1999-12-15  Mark Mitchell  <mark@codesourcery.com>
+
+	* builtins.c (expand_builtin_mathfn): Make sure not to expand the
+	argument more than once.
+
 1999-12-15  Jason Merrill  <jason@casey.cygnus.com>
 
 	* stmt.c (expand_decl): Expand upper bound of a dynamic array.
diff --git a/gcc/builtins.c b/gcc/builtins.c
index ffc84fd9ccd..f03a53f864c 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -1182,9 +1182,16 @@ expand_builtin_mathfn (exp, target, subtarget)
       && TREE_CODE (TREE_VALUE (arglist)) != PARM_DECL)
     {
       exp = copy_node (exp);
-      arglist = copy_node (arglist);
       TREE_OPERAND (exp, 1) = arglist;
+      /* Wrap the computation of the argument in a SAVE_EXPR.  That
+	 way, if we need to expand the argument again (as in the
+	 flag_errno_math case below where we cannot directly set
+	 errno), we will not perform side-effects more than once.
+	 Note that here we're mutating the original EXP as well as the
+	 copy; that's the right thing to do in case the original EXP
+	 is expanded later.  */
       TREE_VALUE (arglist) = save_expr (TREE_VALUE (arglist));
+      arglist = copy_node (arglist);
     }
   op0 = expand_expr (TREE_VALUE (arglist), subtarget, VOIDmode, 0);