pointer_diff depends on range_operator::fold_range to do the generic
fold, which invokes wi_fold on subranges. It also in turn invokes
op1_op2_relation_effect for relation effects.
This worked fine when pointers were implemented with irange, but when
the transition to prange was made, a new version of fold_range is
invoked by dispatch which uses prange operators. The default fold_range
for prange does nothing, expecting the few pointer operators which need
it to implement their own fold_range. As a result all calls to
fold_range for pointer_diff were returning false, which translates to
VARYING.
This PR demonstrates a dependency on knowing the relation between the
operands is VREL_NE, in which case pointer_diff should return a non-zero
result instead of varying. This patch implements the pointer_diff
version of fold_range.
I am also auditing the other prange operators to see if similar dispatch
related issues were missed.
Bootstrapped on x86_64-pc-linux-gnu with no regressions. Pushed.
Andrew
From 774ad67fba458dd1beaa0f2d3e389aac46ca18b5 Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacl...@redhat.com>
Date: Mon, 21 Oct 2024 16:32:00 -0400
Subject: [PATCH] Implement operator_pointer_diff::fold_range
prange has no default fold_range processing like irange does, so each
pointer specific operator needs to implement its own fold routine.
PR tree-optimization/117222
gcc/
* range-op-ptr.cc (operator_pointer_diff::fold_range): New.
(operator_pointer_diff::op1_op2_relation_effect): Remove irange
variant.
(operator_pointer_diff::update_bitmask): Likewise.
gcc/testsuite
* g++.dg/pr117222.C: New.
---
gcc/range-op-ptr.cc | 37 ++++++++++++++++++---------------
gcc/testsuite/g++.dg/pr117222.C | 16 ++++++++++++++
2 files changed, 36 insertions(+), 17 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/pr117222.C
diff --git a/gcc/range-op-ptr.cc b/gcc/range-op-ptr.cc
index 24e206c00cd..07a551618f9 100644
--- a/gcc/range-op-ptr.cc
+++ b/gcc/range-op-ptr.cc
@@ -567,25 +567,38 @@ pointer_or_operator::wi_fold (irange &r, tree type,
class operator_pointer_diff : public range_operator
{
+ using range_operator::fold_range;
using range_operator::update_bitmask;
using range_operator::op1_op2_relation_effect;
- virtual bool op1_op2_relation_effect (irange &lhs_range,
- tree type,
- const irange &op1_range,
- const irange &op2_range,
- relation_kind rel) const;
+ virtual bool fold_range (irange &r, tree type,
+ const prange &op1,
+ const prange &op2,
+ relation_trio trio) const final override;
virtual bool op1_op2_relation_effect (irange &lhs_range,
tree type,
const prange &op1_range,
const prange &op2_range,
relation_kind rel) const final override;
- void update_bitmask (irange &r, const irange &lh, const irange &rh) const
- { update_known_bitmask (r, POINTER_DIFF_EXPR, lh, rh); }
void update_bitmask (irange &r,
const prange &lh, const prange &rh) const final override
{ update_known_bitmask (r, POINTER_DIFF_EXPR, lh, rh); }
} op_pointer_diff;
+bool
+operator_pointer_diff::fold_range (irange &r, tree type,
+ const prange &op1,
+ const prange &op2,
+ relation_trio trio) const
+{
+ gcc_checking_assert (r.supports_type_p (type));
+
+ r.set_varying (type);
+ relation_kind rel = trio.op1_op2 ();
+ op1_op2_relation_effect (r, type, op1, op2, rel);
+ update_bitmask (r, op1, op2);
+ return true;
+}
+
bool
operator_pointer_diff::op1_op2_relation_effect (irange &lhs_range, tree type,
const prange &op1_range,
@@ -602,16 +615,6 @@ operator_pointer_diff::op1_op2_relation_effect (irange &lhs_range, tree type,
return minus_op1_op2_relation_effect (lhs_range, type, op1, op2, rel);
}
-bool
-operator_pointer_diff::op1_op2_relation_effect (irange &lhs_range, tree type,
- const irange &op1_range,
- const irange &op2_range,
- relation_kind rel) const
-{
- return minus_op1_op2_relation_effect (lhs_range, type, op1_range, op2_range,
- rel);
-}
-
bool
operator_identity::fold_range (prange &r, tree type ATTRIBUTE_UNUSED,
const prange &lh ATTRIBUTE_UNUSED,
diff --git a/gcc/testsuite/g++.dg/pr117222.C b/gcc/testsuite/g++.dg/pr117222.C
new file mode 100644
index 00000000000..60cf6e30ed5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr117222.C
@@ -0,0 +1,16 @@
+// { dg-do compile }
+// { dg-require-effective-target c++11 }
+// { dg-options "-O3 -fdump-tree-evrp" }
+
+#include <vector>
+int main()
+{
+ std::vector<int> c {1,2,3,0};
+ while(c.size() > 0 && c.back() == 0)
+ {
+ auto sz = c.size() -1;
+ c.resize(sz);
+ }
+ return 0;
+}
+/* { dg-final { scan-tree-dump "Global Exported.*\[-INF, -1\]\[1, +INF\]" "evrp" } } */
--
2.45.0
