On July 22, 2018 9:15:50 PM GMT+02:00, Jakub Jelinek <ja...@redhat.com> wrote:
>Hi!
>
>A couple of -fcompare-debug=-Wsomething PRs have been filed recently,
>this
>fixes one of them. Changing code generation based on TREE_NO_WARNING
>flag
>which usually gets set only in the warning code, or on warn_* option is
>undesirable. This patch prevents that kind of folding regardless of
>the
>warning options, the GIMPLE optimizers can handle it fine (but it makes
>a
>difference with -O0).
>
>Bootstrapped/regtested on x86_64-linux (only, i686-linux bootstrap is
>broken), ok for trunk?
OK.
Richard.
>2018-07-22 Jakub Jelinek <ja...@redhat.com>
>
> PR c++/86569
> * cp-gimplify.c (cp_fold): Don't fold comparisons into other kind
> of expressions other than INTEGER_CST regardless of TREE_NO_WARNING
> or warn_nonnull_compare.
>
> * g++.dg/warn/Wnonnull-compare-9.C: New test.
>
>--- gcc/cp/cp-gimplify.c.jj 2018-07-16 09:43:03.237023048 +0200
>+++ gcc/cp/cp-gimplify.c 2018-07-19 11:44:24.881759294 +0200
>@@ -2381,21 +2381,26 @@ cp_fold (tree x)
> else
> x = fold (x);
>
>- if (TREE_NO_WARNING (org_x)
>- && warn_nonnull_compare
>- && COMPARISON_CLASS_P (org_x))
>+ /* This is only needed for -Wnonnull-compare and only if
>+ TREE_NO_WARNING (org_x), but to avoid that option affecting code
>+ generation, we do it always. */
>+ if (COMPARISON_CLASS_P (org_x))
> {
> if (x == error_mark_node || TREE_CODE (x) == INTEGER_CST)
> ;
> else if (COMPARISON_CLASS_P (x))
>- TREE_NO_WARNING (x) = 1;
>+ {
>+ if (TREE_NO_WARNING (org_x) && warn_nonnull_compare)
>+ TREE_NO_WARNING (x) = 1;
>+ }
> /* Otherwise give up on optimizing these, let GIMPLE folders
> optimize those later on. */
> else if (op0 != TREE_OPERAND (org_x, 0)
> || op1 != TREE_OPERAND (org_x, 1))
> {
> x = build2_loc (loc, code, TREE_TYPE (org_x), op0, op1);
>- TREE_NO_WARNING (x) = 1;
>+ if (TREE_NO_WARNING (org_x) && warn_nonnull_compare)
>+ TREE_NO_WARNING (x) = 1;
> }
> else
> x = org_x;
>--- gcc/testsuite/g++.dg/warn/Wnonnull-compare-9.C.jj 2018-07-19
>11:57:41.909727597 +0200
>+++ gcc/testsuite/g++.dg/warn/Wnonnull-compare-9.C 2018-07-19
>11:57:14.627696497 +0200
>@@ -0,0 +1,11 @@
>+// PR c++/86569
>+// { dg-do compile }
>+// { dg-options "-fcompare-debug=-Wnonnull-compare" }
>+
>+bool b;
>+
>+int
>+main ()
>+{
>+ return ((!b) != 0);
>+}
>
> Jakub
