Well, after talking with Andrew it seems that X << Y being non-zero
also implies X is non-zero. So we don't even need relationals here.
So, I leave gori relationals in his capable hands, while I test this
much simpler patch which fixes the PR with no additional
infrastructure ;-).
Will push pending tests.
Aldy
On Fri, Oct 1, 2021 at 2:43 PM Aldy Hernandez <al...@redhat.com> wrote:
>
> Knowing that X << X is non-zero means X is also non-zero. This patch
> teaches this this to range-ops.
>
> As usual, the big twiddling experts could come up with all sorts of
> fancy enhancements in this area, and we welcome all patches :).
>
> I will push this pending tests.
>
> gcc/ChangeLog:
>
> PR tree-optimization/102546
> * range-op.cc (operator_lshift::op1_range): Handle EQ_EXPR
> relation.
> ---
> gcc/range-op.cc | 19 ++++++++++++++++---
> gcc/testsuite/gcc.dg/tree-ssa/pr102546.c | 23 +++++++++++++++++++++++
> 2 files changed, 39 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr102546.c
>
> diff --git a/gcc/range-op.cc b/gcc/range-op.cc
> index 5e37133026d..53f3be4266e 100644
> --- a/gcc/range-op.cc
> +++ b/gcc/range-op.cc
> @@ -2075,9 +2075,14 @@ operator_lshift::op1_range (irange &r,
> tree type,
> const irange &lhs,
> const irange &op2,
> - relation_kind rel ATTRIBUTE_UNUSED) const
> + relation_kind rel) const
> {
> tree shift_amount;
> + int_range<2> adjust (type);
> +
> + if (rel == EQ_EXPR && !lhs.contains_p (build_zero_cst (type)))
> + adjust.set_nonzero (type);
> +
> if (op2.singleton_p (&shift_amount))
> {
> wide_int shift = wi::to_wide (shift_amount);
> @@ -2086,10 +2091,11 @@ operator_lshift::op1_range (irange &r,
> if (wi::ge_p (shift, wi::uhwi (TYPE_PRECISION (type),
> TYPE_PRECISION (op2.type ())),
> UNSIGNED))
> - return false;
> + goto done;
> if (shift == 0)
> {
> r = lhs;
> + r.intersect (adjust);
> return true;
> }
>
> @@ -2126,9 +2132,16 @@ operator_lshift::op1_range (irange &r,
>
> if (utype != type)
> range_cast (r, type);
> + r.intersect (adjust);
> return true;
> }
> - return false;
> +
> + done:
> + if (adjust.varying_p ())
> + return false;
> +
> + r = adjust;
> + return true;
> }
>
> bool
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr102546.c
> b/gcc/testsuite/gcc.dg/tree-ssa/pr102546.c
> new file mode 100644
> index 00000000000..4bd98747732
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr102546.c
> @@ -0,0 +1,23 @@
> +// { dg-do compile }
> +// { dg-options "-O3 -fdump-tree-optimized" }
> +
> +static int a;
> +static char b, c, d;
> +void bar(void);
> +void foo(void);
> +
> +int main() {
> + int f = 0;
> + for (; f <= 5; f++) {
> + bar();
> + b = b && f;
> + d = f << f;
> + if (!(a >= d || f))
> + foo();
> + c = 1;
> + for (; c; c = 0)
> + ;
> + }
> +}
> +
> +// { dg-final { scan-tree-dump-not "foo" "optimized" } }
> --
> 2.31.1
>
From fa11285b9ff1d75c877369c1df7760c3f76a4fe5 Mon Sep 17 00:00:00 2001
From: Aldy Hernandez <al...@redhat.com>
Date: Fri, 1 Oct 2021 13:05:36 +0200
Subject: [PATCH] [PR102546] X << Y being non-zero implies X is also non-zero.
This patch teaches this to range-ops.
Tested on x86-64 Linux.
gcc/ChangeLog:
PR tree-optimization/102546
* range-op.cc (operator_lshift::op1_range): Teach range-ops that
X << Y is non-zero implies X is also non-zero.
---
gcc/range-op.cc | 18 ++++++++++++++----
gcc/testsuite/gcc.dg/tree-ssa/pr102546.c | 23 +++++++++++++++++++++++
2 files changed, 37 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr102546.c
diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 5e37133026d..2baca4a197f 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -2078,6 +2078,12 @@ operator_lshift::op1_range (irange &r,
relation_kind rel ATTRIBUTE_UNUSED) const
{
tree shift_amount;
+
+ if (!lhs.contains_p (build_zero_cst (type)))
+ r.set_nonzero (type);
+ else
+ r.set_varying (type);
+
if (op2.singleton_p (&shift_amount))
{
wide_int shift = wi::to_wide (shift_amount);
@@ -2089,21 +2095,24 @@ operator_lshift::op1_range (irange &r,
return false;
if (shift == 0)
{
- r = lhs;
+ r.intersect (lhs);
return true;
}
// Work completely in unsigned mode to start.
tree utype = type;
+ int_range_max tmp_range;
if (TYPE_SIGN (type) == SIGNED)
{
int_range_max tmp = lhs;
utype = unsigned_type_for (type);
range_cast (tmp, utype);
- op_rshift.fold_range (r, utype, tmp, op2);
+ op_rshift.fold_range (tmp_range, utype, tmp, op2);
}
else
- op_rshift.fold_range (r, utype, lhs, op2);
+ op_rshift.fold_range (tmp_range, utype, lhs, op2);
+
+ r.intersect (tmp_range);
// Start with ranges which can produce the LHS by right shifting the
// result by the shift amount.
@@ -2128,7 +2137,8 @@ operator_lshift::op1_range (irange &r,
range_cast (r, type);
return true;
}
- return false;
+
+ return !r.varying_p ();
}
bool
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr102546.c b/gcc/testsuite/gcc.dg/tree-ssa/pr102546.c
new file mode 100644
index 00000000000..4bd98747732
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr102546.c
@@ -0,0 +1,23 @@
+// { dg-do compile }
+// { dg-options "-O3 -fdump-tree-optimized" }
+
+static int a;
+static char b, c, d;
+void bar(void);
+void foo(void);
+
+int main() {
+ int f = 0;
+ for (; f <= 5; f++) {
+ bar();
+ b = b && f;
+ d = f << f;
+ if (!(a >= d || f))
+ foo();
+ c = 1;
+ for (; c; c = 0)
+ ;
+ }
+}
+
+// { dg-final { scan-tree-dump-not "foo" "optimized" } }
--
2.31.1
