From ba3ad5e002ee9c9523e4b61eb47b1b510d8841ef Mon Sep 17 00:00:00 2001 From: Philippe De Muyter Date: Thu, 19 Mar 1998 20:27:18 +0100 Subject: [PATCH] fold-const.c (fold): Replace sign-extension of a zero extended value by a single zero extension. * fold-const.c (fold): Replace sign-extension of a zero extended value by a single zero extension. From-SVN: r18713 --- gcc/ChangeLog | 5 +++++ gcc/fold-const.c | 7 +++++++ 2 files changed, 12 insertions(+) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 391fd9ccbe6..e25b040113e 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +Thu Mar 19 20:30:31 1998 Philippe De Muyter + + * fold-const.c (fold): Replace sign-extension of a zero extended + value by a single zero extension. + Thu Mar 19 00:58:07 1998 Jason Merrill * except.c (init_eh): Do nothing. diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 3a24e4c2df5..4fcd7448303 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -4101,6 +4101,13 @@ fold (expr) && ! final_ptr) return convert (final_type, TREE_OPERAND (TREE_OPERAND (t, 0), 0)); + /* If we have a sign-extension of a zero-extended value, we can + replace that by a single zero-extension. */ + if (inside_int && inter_int && final_int + && inside_prec < inter_prec && inter_prec < final_prec + && inside_unsignedp && !inter_unsignedp) + return convert (final_type, TREE_OPERAND (TREE_OPERAND (t, 0), 0)); + /* Two conversions in a row are not needed unless: - some conversion is floating-point (overstrict for now), or - the intermediate type is narrower than both initial and -- 2.30.2