On Thu, Jan 19, 2023 at 10:19 AM Jan-Benedict Glaw <jbg...@lug-owl.de> wrote:
>
> On Thu, 2022-12-22 17:42:16 +0000, Andrew Carlotti via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> > New patch below, bootstrapped and regression tested on
> > aarch64-unknown-linux-gnu and x86_64-pc-linux-gnu - ok to merge?
>
> > diff --git a/gcc/tree-ssa-loop-niter.cc b/gcc/tree-ssa-loop-niter.cc
> > index
> > fece876099c1687569d6351e7d2416ea6acae5b5..ce2441f2a6dbdf2d8fe42755d5d1abd8a631bb5c
> > 100644
> > --- a/gcc/tree-ssa-loop-niter.cc
> > +++ b/gcc/tree-ssa-loop-niter.cc
> > @@ -42,6 +42,7 @@ along with GCC; see the file COPYING3. If not see
> > #include "tree-chrec.h"
> > #include "tree-scalar-evolution.h"
> > #include "tree-dfa.h"
> > +#include "internal-fn.h"
> > #include "gimple-range.h"
> >
> >
> > @@ -2198,6 +2199,224 @@ number_of_iterations_popcount (loop_p loop, edge
> > exit,
> > return true;
> > }
> >
> > +/* Return an expression that counts the leading/trailing zeroes of src.
> > +
> > + If define_at_zero is true, then the built expression will be defined to
> > + return the precision of src when src == 0 (using either a conditional
> > + expression or a suitable internal function).
> > + Otherwise, we can elide the conditional expression and let src = 0
> > invoke
> > + undefined behaviour. */
> > +
> > +static tree
> > +build_cltz_expr (tree src, bool leading, bool define_at_zero)
> > +{
> [...]
> > +
> > + tree call;
> > + if (use_ifn)
> > + {
> > + call = build_call_expr_internal_loc (UNKNOWN_LOCATION, ifn,
> > + integer_type_node, 1, src);
> > + int val;
> > + scalar_int_mode mode = SCALAR_INT_TYPE_MODE (utype);
> ^^^^^^^^^^^^^^^^^^^^
>
> This will give us a new unused variable warning.
I wonder if hardening the defaults.h macros like
#define CLZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE) (((MODE), (VALUE)), 0)
fixes that and makes sense (also to avoid losing side-effects for the arguments)
Richard.
> > + int optab_defined_at_zero
> > + = leading ? CLZ_DEFINED_VALUE_AT_ZERO (mode, val)
> > + : CTZ_DEFINED_VALUE_AT_ZERO (mode, val);
> > + if (define_at_zero && !(optab_defined_at_zero == 2 && val == prec))
> > + {
> > + tree is_zero = fold_build2 (NE_EXPR, boolean_type_node, src,
> > + build_zero_cst (TREE_TYPE (src)));
> > + call = fold_build3(COND_EXPR, integer_type_node, is_zero, call,
> > + build_int_cst (integer_type_node, prec));
> > + }
> > + }
>
> MfG, JBG
>
> --
