On Wed, 6 Aug 2014, Richard Biener wrote:
>
> The following fixes the remaining ICEs I see when testing all
> languages (but ada and go).
>
> The tree-cfg.c hunk highlights one change in the behavior
> of fold_stmt, namely that it now follows SSA edges by default.
> Maybe that's undesired? On a related note, fold_stmt_inplace
> preserves the actual statement object gsi_stmt points to,
> but in reality callers use it to avoid creating new SSA names
> thus would it be ok if fold_stmt_inplace made sure to
> preserve the number of statements (and only change what
> gsi points to) only?
>
> Bootstrapped / tested on x86_64-unknown-linux-gnu, applied.
The following clarifies the comment.
Richard.
2014-08-06 Richard Biener <rguent...@suse.de>
* tree-cfg.c (replace_uses_by): Clarify added comment.
Index: gcc/tree-cfg.c
===================================================================
--- gcc/tree-cfg.c (revision 213655)
+++ gcc/tree-cfg.c (working copy)
@@ -1748,11 +1748,12 @@ replace_uses_by (tree name, tree val)
/* If we have sth like
neighbor_29 = <name> + -1;
_33 = <name> + neighbor_29;
- and end up visiting _33 first then folding will
- simplify the stmt to _33 = <name>; and the new
- immediate use will be inserted before the stmt
- iterator marker and thus we fail to visit it
- again, ICEing within the has_zero_uses assert.
+ and substitute 1 for <name> then when visiting
+ _33 first then folding will simplify the stmt
+ to _33 = <name>; and the new immediate use will
+ be inserted before the stmt iterator marker and
+ thus we fail to visit it again, ICEing within the
+ has_zero_uses assert.
Avoid that by never following SSA edges. */
if (fold_stmt (&gsi, no_follow_ssa_edges))
stmt = gsi_stmt (gsi);
