From 0730d9a6b856f6887bfffc4ce45d4164563a476e Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacleod@redhat.com>
Date: Tue, 17 Jan 2023 11:39:47 -0500
Subject: [PATCH 3/3] Add op2_range to pointer_plus.
Implement op2_range for pointer_plus to determine the offset (operand 2) is
zero or non-zero based on equality/inequality between the LHS and op1.
Also allow GORI computations to continue if the LHS is VARYING and there
is also a relation.
PR tree-optimization/108385
gcc/
* gimple-range-gori.cc (gori_compute::compute_operand_range):
Allow VARYING computations to continue if there is a relation.
* range-op.cc (pointer_plus_operator::op2_range): New.
gcc/testsuite/
* gcc.dg/pr108385.c: New.
---
gcc/gimple-range-gori.cc | 13 +++++++----
gcc/range-op.cc | 23 +++++++++++++++++++
gcc/testsuite/gcc.dg/pr108385.c | 39 +++++++++++++++++++++++++++++++++
3 files changed, 71 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr108385.c
@@ -607,10 +607,6 @@ gori_compute::compute_operand_range (vrange &r, gimple *stmt,
{
value_relation vrel;
value_relation *vrel_ptr = rel;
- // If the lhs doesn't tell us anything, neither will unwinding further.
- if (lhs.varying_p ())
- return false;
-
// Empty ranges are viral as they are on an unexecutable path.
if (lhs.undefined_p ())
{
@@ -657,10 +653,19 @@ gori_compute::compute_operand_range (vrange &r, gimple *stmt,
if (!op1_in_chain && !op2_in_chain)
return false;
+ // If the lhs doesn't tell us anything and there are no relations, there
+ // is nothing to be learned.
+ if (lhs.varying_p () && !vrel_ptr)
+ return false;
+
bool res;
// Process logicals as they have special handling.
if (is_gimple_logical_p (stmt))
{
+ // If the lhs doesn't tell us anything, neither will combining operands.
+ if (lhs.varying_p ())
+ return false;
+
unsigned idx;
if ((idx = tracer.header ("compute_operand ")))
{
@@ -4212,6 +4212,10 @@ public:
const wide_int &lh_ub,
const wide_int &rh_lb,
const wide_int &rh_ub) const;
+ virtual bool op2_range (irange &r, tree type,
+ const irange &lhs,
+ const irange &op1,
+ relation_trio = TRIO_VARYING) const;
} op_pointer_plus;
void
@@ -4258,6 +4262,25 @@ pointer_plus_operator::wi_fold (irange &r, tree type,
r.set_varying (type);
}
+bool
+pointer_plus_operator::op2_range (irange &r, tree type,
+ const irange &lhs ATTRIBUTE_UNUSED,
+ const irange &op1 ATTRIBUTE_UNUSED,
+ relation_trio trio) const
+{
+ relation_kind rel = trio.lhs_op1 ();
+ r.set_varying (type);
+
+ // If the LHS and OP1 are equal, the op2 must be zero.
+ if (rel == VREL_EQ)
+ r.set_zero (type);
+ // If the LHS and OP1 are not equal, the offset must be non-zero.
+ else if (rel == VREL_NE)
+ r.set_nonzero (type);
+ else
+ return false;
+ return true;
+}
class pointer_min_max_operator : public range_operator
{
new file mode 100644
@@ -0,0 +1,39 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-evrp" } */
+
+void bar(char *);
+
+/* Ensure that PTR1 = PTR2 + OFF properly picks up the zero and non-zero
+ properties if PTR1 and PTR2 are known equal or non-equal. */
+
+void foo1 (char *p, char *pp, int off)
+{
+ char *q = p + off;
+ if (q != p)
+ {
+ if (off == 0)
+ bar (q);
+ }
+ else
+ {
+ if (off != 0)
+ bar (p);
+ }
+}
+
+void foo2 (char *p, char *pp, int off)
+{
+ char *q = p + off;
+ if (q == p)
+ {
+ if (off != 0)
+ bar (p);
+ }
+ else
+ {
+ if (off == 0)
+ bar (q);
+ }
+}
+
+/* { dg-final { scan-tree-dump-not "bar" "evrp" } } */
--
2.39.0