From f1acad4e43908e90ca2b5155a878639cbea4c4e1 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Sun, 12 Jan 2020 15:09:22 -0500
Subject: [PATCH] PR c++/93238 - short right-shift with enum.
My earlier patch to reintroduce short_shift failed to adjust for the C++
front end use of const_op1 rather than op1.
* typeck.c (cp_build_binary_op): Use folded op1 for short_shift.
---
gcc/cp/ChangeLog | 5 +++++
gcc/cp/typeck.c | 8 +++++---
gcc/testsuite/g++.dg/expr/rshift1.C | 8 ++++++++
3 files changed, 18 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/expr/rshift1.C
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 1dad238028ac..9b226b84e73a 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2020-01-13 Jason Merrill <jason@redhat.com>
+
+ PR c++/93238 - short right-shift with enum.
+ * typeck.c (cp_build_binary_op): Use folded op1 for short_shift.
+
2020-01-10 Jason Merrill <jason@redhat.com>
* typeck.c (cp_build_binary_op): Restore short_shift code.
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 7b653cebca0a..8955442349f9 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -4848,7 +4848,7 @@ cp_build_binary_op (const op_location_t &location,
}
else
{
- if (!integer_zerop (op1))
+ if (!integer_zerop (const_op1))
short_shift = 1;
if (compare_tree_int (const_op1, TYPE_PRECISION (type0)) >= 0
@@ -5599,6 +5599,7 @@ cp_build_binary_op (const op_location_t &location,
{
int unsigned_arg;
tree arg0 = get_narrower (op0, &unsigned_arg);
+ tree const_op1 = cp_fold_rvalue (op1);
final_type = result_type;
@@ -5606,10 +5607,11 @@ cp_build_binary_op (const op_location_t &location,
unsigned_arg = TYPE_UNSIGNED (TREE_TYPE (op0));
if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type)
- && tree_int_cst_sgn (op1) > 0
+ && tree_int_cst_sgn (const_op1) > 0
/* We can shorten only if the shift count is less than the
number of bits in the smaller type size. */
- && compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0
+ && compare_tree_int (const_op1,
+ TYPE_PRECISION (TREE_TYPE (arg0))) < 0
/* We cannot drop an unsigned shift after sign-extension. */
&& (!TYPE_UNSIGNED (final_type) || unsigned_arg))
{
diff --git a/gcc/testsuite/g++.dg/expr/rshift1.C b/gcc/testsuite/g++.dg/expr/rshift1.C
new file mode 100644
index 000000000000..2f81c02aa672
--- /dev/null
+++ b/gcc/testsuite/g++.dg/expr/rshift1.C
@@ -0,0 +1,8 @@
+// PR c++/93238
+
+short s;
+enum { zero };
+int fn(int i)
+{
+ return s >> zero;
+}
--
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