From 0f7ccc063a42407f91fa52a54cc480950a45e75c Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacleod@redhat.com>
Date: Thu, 17 Jun 2021 13:39:02 -0400
Subject: [PATCH 6/7] Add relation between LHS and op1 for casts and copies.
* range-op.cc (operator_cast::lhs_op1_relation): New.
(operator_identity::lhs_op1_relation): Mew.
---
gcc/range-op.cc | 41 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 41 insertions(+)
@@ -2115,6 +2115,10 @@ public:
const irange &lhs,
const irange &op2,
relation_kind rel = VREL_NONE) const;
+ virtual enum tree_code lhs_op1_relation (const irange &lhs,
+ const irange &op1,
+ const irange &op2) const;
+
private:
bool truncating_cast_p (const irange &inner, const irange &outer) const;
bool inside_domain_p (const wide_int &min, const wide_int &max,
@@ -2123,6 +2127,27 @@ private:
const irange &outer) const;
} op_convert;
+// Determine if there is a relationship between LHS and OP1.
+
+enum tree_code
+operator_cast::lhs_op1_relation (const irange &lhs,
+ const irange &op1,
+ const irange &op2 ATTRIBUTE_UNUSED) const
+{
+ if (op1.undefined_p ())
+ return VREL_NONE;
+ // We can't make larger types equivalent to smaller types because we can
+ // miss sign extensions in a chain of casts.
+ // u32 = 0xfffff
+ // s32 = (s32) u32
+ // s64 = (s64) s32
+ // we cant simply "convert" s64 = (s64)u32 or we get positive 0xffff
+ // value instead of sign extended negative value.
+ if (TYPE_PRECISION (lhs.type ()) == TYPE_PRECISION (op1.type ()))
+ return EQ_EXPR;
+ return VREL_NONE;
+}
+
// Return TRUE if casting from INNER to OUTER is a truncating cast.
inline bool
@@ -3325,8 +3350,24 @@ public:
const irange &lhs,
const irange &op2,
relation_kind rel = VREL_NONE) const;
+ virtual enum tree_code lhs_op1_relation (const irange &lhs,
+ const irange &op1,
+ const irange &op2) const;
} op_identity;
+// Determine if there is a relationship between LHS and OP1.
+
+enum tree_code
+operator_identity::lhs_op1_relation (const irange &lhs,
+ const irange &op1 ATTRIBUTE_UNUSED,
+ const irange &op2 ATTRIBUTE_UNUSED) const
+{
+ if (lhs.undefined_p ())
+ return VREL_NONE;
+ // Simply a copy, so they are equivalent.
+ return EQ_EXPR;
+}
+
bool
operator_identity::fold_range (irange &r, tree type ATTRIBUTE_UNUSED,
const irange &lh,
--
2.17.2