From: Aldy Hernandez <aldyh@redhat.com>
To: GCC patches <gcc-patches@gcc.gnu.org>
Subject: [PATCH] Handle EQ_EXPR relation for operator_lshift.
Date: Fri, 1 Oct 2021 14:43:08 +0200 [thread overview]
Message-ID: <20211001124306.1458223-3-aldyh@redhat.com> (raw)
In-Reply-To: <20211001124306.1458223-1-aldyh@redhat.com>
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
next prev parent reply other threads:[~2021-10-01 12:43 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-01 12:43 [COMMITTED] Remove shadowed oracle field Aldy Hernandez
2021-10-01 12:43 ` [PATCH] Pass relations down to range_operator::op[12]_range Aldy Hernandez
2021-10-01 13:38 ` Andrew MacLeod
2021-10-01 12:43 ` Aldy Hernandez [this message]
2021-10-01 14:52 ` [PATCH] Handle EQ_EXPR relation for operator_lshift Aldy Hernandez
2021-10-02 19:50 ` Aldy Hernandez
2021-10-02 20:53 ` Jeff Law
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