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* [gcc r12-2258] Do not register a cast as an equivalence.
@ 2021-07-12 18:37 Andrew Macleod
0 siblings, 0 replies; only message in thread
From: Andrew Macleod @ 2021-07-12 18:37 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:a1539b797a06e03b08e1f1de28ad0d19a3956616
commit r12-2258-ga1539b797a06e03b08e1f1de28ad0d19a3956616
Author: Andrew MacLeod <amacleod@redhat.com>
Date: Mon Jul 12 11:38:17 2021 -0400
Do not register a cast as an equivalence.
Registering an equivalence between objects of the same size in a cast can
cause other relations to be incorrect.
gcc/
PR tree-optimization/101335
* range-op.cc (operator_cast::lhs_op1_relation): Delete.
gcc/testsuite/
* gcc.dg/tree-ssa/pr101335.c: New.
Diff:
---
gcc/range-op.cc | 25 -------------------------
gcc/testsuite/gcc.dg/tree-ssa/pr101335.c | 17 +++++++++++++++++
2 files changed, 17 insertions(+), 25 deletions(-)
diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index f8e4c6d4e49..08000465fd9 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -2159,10 +2159,6 @@ 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,
@@ -2171,27 +2167,6 @@ 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
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr101335.c b/gcc/testsuite/gcc.dg/tree-ssa/pr101335.c
new file mode 100644
index 00000000000..921362c2954
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr101335.c
@@ -0,0 +1,17 @@
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+unsigned a = 0xFFFFFFFF;
+int b;
+int main()
+{
+ int c = ~a;
+ unsigned d = c - 10;
+ if (d > c)
+ c = 20;
+ b = -(c | 0);
+ if (b > -8)
+ __builtin_abort ();
+ return 0;
+}
+
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