On Tue, Jun 02, 2015 at 09:25:32PM +0200, Marek Polacek wrote:
> On Fri, May 29, 2015 at 08:49:58PM +0000, Joseph Myers wrote:
> > On Mon, 25 May 2015, Marek Polacek wrote:
> >
> > > +/* Warn if signed left shift overflows. Note that we don't warn
> > > + about left-shifting 1 into the sign bit; cf.
> > > +
> > > <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3367.html#1457>
> > > + for C++ and
> > > <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1817.htm>
> > > + for C. LOC is a location of the shift; OP0 and OP1 are the operands.
> > > + Return true if an overflow is detected, false otherwise. */
> >
> > But for C that was declared not a defect. See
> > <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1931.htm#dr_463>. So
> > for C99 and later we *should* consider this an overflow (for the purposes
> > of pedwarns-if-pedantic in contexts where an integer constant expression
> > is required; maybe -Wshift-overflow=2 for other warnings?). If then a
> > future C standard changes things here (in the list of issues to be
> > considered for a future C standard in Standing Document 3,
> > <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1917.htm>), then, as a
> > non-defect change, it should be considered a non-overflow in GCC only for
> > future C standard versions as well as C90.
> >
> > (Although treating something as not an integer constant expression does
> > have consequences beyond pedwarns-if-pedantic - a zero derived from that
> > expression is not a null pointer constant and that can affect the types of
> > conditional expressions - I don't expect any significant breakage of real
> > code from that.)
>
> Well, ok then. This new version incorporates Richard S.'s suggestion,
> and warns even for 1 << 31 in C99/C11 (also in C90 when -Wshift-overflow
> is explicitely specified). For C++, it warns about 1 << 31 by default
> only in C++11 mode, in C++14 never, otherwise only if -Wshift-overflow
> is specified.
>
> But the fallout seems to be nonnegligible. So I think the default should
> be -Wshift-overflow=1 that doesn't warn about 1 << 31, but still rejects
> e.g. enum { A = 1 << 31 };. And -Wshift-overflow=2 would warn even about
> 1 << 31. (Perhaps this is exactly what you had in mind, but I'm not sure.)
Done in the following. I think this is the best approach. The documentation
hopefully makes it clear what's the intended behavior.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2015-06-03 Marek Polacek <pola...@redhat.com>
Richard Sandiford <richard.sandif...@arm.com>
PR c++/55095
* c-common.c (c_fully_fold_internal): Warn about left shift overflows.
Use EXPR_LOC_OR_LOC.
(maybe_warn_shift_overflow): New function.
* c-common.h (maybe_warn_shift_overflow): Declare.
* c-opts.c (c_common_post_options): Set warn_shift_overflow.
* c.opt (Wshift-overflow): New option.
* c-typeck.c (digest_init): Pass OPT_Wpedantic to pedwarn_init.
(build_binary_op): Warn about left shift overflows.
* typeck.c (cp_build_binary_op): Warn about left shift overflows.
* doc/invoke.texi: Document -Wshift-overflow and -Wshift-overflow=.
* c-c++-common/Wshift-overflow-1.c: New test.
* c-c++-common/Wshift-overflow-2.c: New test.
* c-c++-common/Wshift-overflow-3.c: New test.
* c-c++-common/Wshift-overflow-4.c: New test.
* c-c++-common/Wshift-overflow-5.c: New test.
* g++.dg/cpp1y/left-shift-1.C: New test.
* gcc.dg/c90-left-shift-2.c: New test.
* gcc.dg/c90-left-shift-3.c: New test.
* gcc.dg/c99-left-shift-2.c: New test.
* gcc.dg/c99-left-shift-3.c: New test.
* gcc.dg/pr40501.c: Use -Wno-shift-overflow.
* gcc.c-torture/execute/pr40386.c: Likewise.
* gcc.dg/vect/pr33373.c: Likewise.
* gcc.dg/vect/vect-shift-2-big-array.c: Likewise.
* gcc.dg/vect/vect-shift-2.c: Likewise.
diff --git gcc/c-family/c-common.c gcc/c-family/c-common.c
index 36c984c..dc31fad 100644
--- gcc/c-family/c-common.c
+++ gcc/c-family/c-common.c
@@ -1371,7 +1371,7 @@ c_fully_fold_internal (tree expr, bool in_init, bool
*maybe_const_operands,
if (TREE_OVERFLOW_P (ret)
&& !TREE_OVERFLOW_P (op0)
&& !TREE_OVERFLOW_P (op1))
- overflow_warning (EXPR_LOCATION (expr), ret);
+ overflow_warning (EXPR_LOC_OR_LOC (expr, input_location), ret);
if (code == LSHIFT_EXPR
&& TREE_CODE (orig_op0) != INTEGER_CST
&& TREE_CODE (TREE_TYPE (orig_op0)) == INTEGER_TYPE
@@ -1401,6 +1401,18 @@ c_fully_fold_internal (tree expr, bool in_init, bool
*maybe_const_operands,
? G_("left shift count >= width of type")
: G_("right shift count >= width of type")));
}
+ if (code == LSHIFT_EXPR
+ /* If either OP0 has been folded to INTEGER_CST... */
+ && ((TREE_CODE (orig_op0) != INTEGER_CST
+ && TREE_CODE (TREE_TYPE (orig_op0)) == INTEGER_TYPE
+ && TREE_CODE (op0) == INTEGER_CST)
+ /* ...or if OP1 has been folded to INTEGER_CST... */
+ || (TREE_CODE (orig_op1) != INTEGER_CST
+ && TREE_CODE (TREE_TYPE (orig_op1)) == INTEGER_TYPE
+ && TREE_CODE (op1) == INTEGER_CST))
+ && c_inhibit_evaluation_warnings == 0)
+ /* ...then maybe we can detect an overflow. */
+ maybe_warn_shift_overflow (loc, op0, op1);
if ((code == TRUNC_DIV_EXPR
|| code == CEIL_DIV_EXPR
|| code == FLOOR_DIV_EXPR
@@ -12226,6 +12238,53 @@ maybe_warn_bool_compare (location_t loc, enum
tree_code code, tree op0,
}
}
+/* Warn if signed left shift overflows. We don't warn
+ about left-shifting 1 into the sign bit in C++14; cf.
+ <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3367.html#1457>
+ LOC is a location of the shift; OP0 and OP1 are the operands.
+ Return true if an overflow is detected, false otherwise. */
+
+bool
+maybe_warn_shift_overflow (location_t loc, tree op0, tree op1)
+{
+ if (TREE_CODE (op0) != INTEGER_CST
+ || TREE_CODE (op1) != INTEGER_CST)
+ return false;
+
+ tree type0 = TREE_TYPE (op0);
+ unsigned int prec0 = TYPE_PRECISION (type0);
+
+ /* Left-hand operand must be signed. */
+ if (TYPE_UNSIGNED (type0))
+ return false;
+
+ /* Handle the left-shifting 1 into the sign bit case. */
+ if (integer_onep (op0)
+ && compare_tree_int (op1, prec0 - 1) == 0)
+ {
+ /* Never warn for C++14 onwards. */
+ if (cxx_dialect >= cxx14)
+ return false;
+ /* Otherwise only if -Wshift-overflow=2. But return
+ true to signal an overflow for the sake of integer
+ constant expressions. */
+ if (warn_shift_overflow < 2)
+ return true;
+ }
+
+ unsigned int min_prec = (wi::min_precision (op0, SIGNED)
+ + TREE_INT_CST_LOW (op1));
+ bool overflowed = min_prec > prec0;
+ if (overflowed && c_inhibit_evaluation_warnings == 0)
+ warning_at (loc, OPT_Wshift_overflow_,
+ "result of %qE requires %u bits to represent, "
+ "but %qT only has %u bits",
+ build2_loc (loc, LSHIFT_EXPR, type0, op0, op1),
+ min_prec, type0, prec0);
+
+ return overflowed;
+}
+
/* The C and C++ parsers both use vectors to hold function arguments.
For efficiency, we keep a cache of unused vectors. This is the
cache. */
diff --git gcc/c-family/c-common.h gcc/c-family/c-common.h
index 61900db..c067f42 100644
--- gcc/c-family/c-common.h
+++ gcc/c-family/c-common.h
@@ -1061,6 +1061,7 @@ extern void record_locally_defined_typedef (tree);
extern void maybe_record_typedef_use (tree);
extern void maybe_warn_unused_local_typedefs (void);
extern void maybe_warn_bool_compare (location_t, enum tree_code, tree, tree);
+extern bool maybe_warn_shift_overflow (location_t, tree, tree);
extern vec<tree, va_gc> *make_tree_vector (void);
extern void release_tree_vector (vec<tree, va_gc> *);
extern vec<tree, va_gc> *make_tree_vector_single (tree);
diff --git gcc/c-family/c-opts.c gcc/c-family/c-opts.c
index 8996fe3..2e9f785 100644
--- gcc/c-family/c-opts.c
+++ gcc/c-family/c-opts.c
@@ -866,6 +866,10 @@ c_common_post_options (const char **pfilename)
if (warn_implicit_int == -1)
warn_implicit_int = flag_isoc99;
+ /* -Wshift-overflow is enabled by default in C99 and C++11 modes. */
+ if (warn_shift_overflow == -1)
+ warn_shift_overflow = cxx_dialect >= cxx11 || flag_isoc99;
+
/* -Wshift-negative-value is enabled by -Wextra in C99 and C++11 modes. */
if (warn_shift_negative_value == -1)
warn_shift_negative_value = (extra_warnings
diff --git gcc/c-family/c.opt gcc/c-family/c.opt
index 285952e..dc760d7 100644
--- gcc/c-family/c.opt
+++ gcc/c-family/c.opt
@@ -780,6 +780,14 @@ Wshadow-ivar
ObjC ObjC++ Var(warn_shadow_ivar) EnabledBy(Wshadow) Init(1) Warning
Warn if a local declaration hides an instance variable
+Wshift-overflow
+C ObjC C++ ObjC++ Warning Alias(Wshift-overflow=, 1, 0)
+Warn if left shift of a signed value overflows
+
+Wshift-overflow=
+C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_shift_overflow)
Init(-1) Warning
+Warn if left shift of a signed value overflows
+
Wshift-count-negative
C ObjC C++ ObjC++ Var(warn_shift_count_negative) Init(1) Warning
Warn if shift count is negative
diff --git gcc/c/c-typeck.c gcc/c/c-typeck.c
index f55d4c6..0d2a7fe 100644
--- gcc/c/c-typeck.c
+++ gcc/c/c-typeck.c
@@ -6909,7 +6909,7 @@ digest_init (location_t init_loc, tree type, tree init,
tree origtype,
inside_init = error_mark_node;
}
else if (require_constant && !maybe_const)
- pedwarn_init (init_loc, 0,
+ pedwarn_init (init_loc, OPT_Wpedantic,
"initializer element is not a constant expression");
return inside_init;
@@ -10630,15 +10630,15 @@ build_binary_op (location_t location, enum tree_code
code,
converted = 1;
}
else if (code0 == VECTOR_TYPE && code1 == VECTOR_TYPE
- && TREE_CODE (TREE_TYPE (type0)) == INTEGER_TYPE
- && TREE_CODE (TREE_TYPE (type1)) == INTEGER_TYPE
- && TYPE_VECTOR_SUBPARTS (type0) == TYPE_VECTOR_SUBPARTS (type1))
+ && TREE_CODE (TREE_TYPE (type0)) == INTEGER_TYPE
+ && TREE_CODE (TREE_TYPE (type1)) == INTEGER_TYPE
+ && TYPE_VECTOR_SUBPARTS (type0) == TYPE_VECTOR_SUBPARTS (type1))
{
result_type = type0;
converted = 1;
}
else if ((code0 == INTEGER_TYPE || code0 == FIXED_POINT_TYPE)
- && code1 == INTEGER_TYPE)
+ && code1 == INTEGER_TYPE)
{
doing_shift = true;
if (TREE_CODE (op1) == INTEGER_CST)
@@ -10680,15 +10680,15 @@ build_binary_op (location_t location, enum tree_code
code,
converted = 1;
}
else if (code0 == VECTOR_TYPE && code1 == VECTOR_TYPE
- && TREE_CODE (TREE_TYPE (type0)) == INTEGER_TYPE
- && TREE_CODE (TREE_TYPE (type1)) == INTEGER_TYPE
- && TYPE_VECTOR_SUBPARTS (type0) == TYPE_VECTOR_SUBPARTS (type1))
+ && TREE_CODE (TREE_TYPE (type0)) == INTEGER_TYPE
+ && TREE_CODE (TREE_TYPE (type1)) == INTEGER_TYPE
+ && TYPE_VECTOR_SUBPARTS (type0) == TYPE_VECTOR_SUBPARTS (type1))
{
result_type = type0;
converted = 1;
}
else if ((code0 == INTEGER_TYPE || code0 == FIXED_POINT_TYPE)
- && code1 == INTEGER_TYPE)
+ && code1 == INTEGER_TYPE)
{
doing_shift = true;
if (TREE_CODE (op0) == INTEGER_CST
@@ -10711,7 +10711,6 @@ build_binary_op (location_t location, enum tree_code
code,
warning_at (location, OPT_Wshift_count_negative,
"left shift count is negative");
}
-
else if (compare_tree_int (op1, TYPE_PRECISION (type0)) >= 0)
{
int_const = false;
@@ -10719,6 +10718,10 @@ build_binary_op (location_t location, enum tree_code
code,
warning_at (location, OPT_Wshift_count_overflow,
"left shift count >= width of type");
}
+ else if (TREE_CODE (op0) == INTEGER_CST
+ && maybe_warn_shift_overflow (location, op0, op1)
+ && flag_isoc99)
+ int_const = false;
}
/* Use the type of the value to be shifted. */
diff --git gcc/cp/typeck.c gcc/cp/typeck.c
index fef4f4f..5e2ab11 100644
--- gcc/cp/typeck.c
+++ gcc/cp/typeck.c
@@ -4360,6 +4360,9 @@ cp_build_binary_op (location_t location,
warning (OPT_Wshift_count_overflow,
"left shift count >= width of type");
}
+ else if (TREE_CODE (const_op0) == INTEGER_CST
+ && (complain & tf_warning))
+ maybe_warn_shift_overflow (location, const_op0, const_op1);
}
/* Avoid converting op1 to result_type later. */
converted = 1;
diff --git gcc/doc/invoke.texi gcc/doc/invoke.texi
index e25bd62..2d83cfd 100644
--- gcc/doc/invoke.texi
+++ gcc/doc/invoke.texi
@@ -273,6 +273,7 @@ Objective-C and Objective-C++ Dialects}.
-Wpointer-arith -Wno-pointer-to-int-cast @gol
-Wredundant-decls -Wno-return-local-addr @gol
-Wreturn-type -Wsequence-point -Wshadow -Wno-shadow-ivar @gol
+-Wshift-overflow -Wshift-overflow=@var{n} @gol
-Wshift-count-negative -Wshift-count-overflow -Wshift-negative-value @gol
-Wsign-compare -Wsign-conversion -Wfloat-conversion @gol
-Wsizeof-pointer-memaccess -Wsizeof-array-argument @gol
@@ -3981,6 +3982,26 @@ Warn if shift count >= width of type. This warning is
enabled by default.
Warn if left shifting a negative value. This warning is enabled by
@option{-Wextra} in C99 and C++11 modes (and newer).
+@item -Wshift-overflow
+@itemx -Wshift-overflow=@var{n}
+@opindex Wshift-overflow
+@opindex Wno-shift-overflow
+Warn about left shift overflows. This warning is enabled by
+default in C99 and C++11 modes (and newer).
+
+@table @gcctabopt
+@item -Wshift-overflow=1
+This is the warning level of @option{-Wshift-overflow} and is enabled
+by default in C99 and C++11 modes (and newer). This warning level does
+not warn about left-shifting 1 into the sign bit. (However, in C, such
+an overflow is still rejected in contexts where an integer constant expression
+is required.)
+
+@item -Wshift-overflow=2
+This warning level also warns about left-shifting 1 into the sign bit,
+unless C++14 mode is active.
+@end table
+
@item -Wswitch
@opindex Wswitch
@opindex Wno-switch
diff --git gcc/testsuite/c-c++-common/Wshift-overflow-1.c
gcc/testsuite/c-c++-common/Wshift-overflow-1.c
index e69de29..9969629 100644
--- gcc/testsuite/c-c++-common/Wshift-overflow-1.c
+++ gcc/testsuite/c-c++-common/Wshift-overflow-1.c
@@ -0,0 +1,58 @@
+/* PR c++/55095 */
+/* { dg-do compile { target int32 } } */
+/* { dg-options "-O" } */
+/* { dg-additional-options "-std=c++11" { target c++ } } */
+
+#define INTM1 (sizeof (int) * __CHAR_BIT__ - 1)
+#define INTM2 (sizeof (int) * __CHAR_BIT__ - 2)
+#define LLONGM1 (sizeof (long long) * __CHAR_BIT__ - 1)
+#define LLONGM2 (sizeof (long long) * __CHAR_BIT__ - 2)
+
+int i1 = 1 << INTM1;
+int i2 = 9 << INTM1; /* { dg-warning "requires 36 bits to represent" } */
+int i3 = 10 << INTM2; /* { dg-warning "requires 35 bits to represent" } */
+int i4 = __INT_MAX__ << 2; /* { dg-warning "requires 34 bits to represent" } */
+int i5 = __INT_MAX__ << INTM1; /* { dg-warning "requires 63 bits to represent"
} */
+int i6 = -1 << INTM1;
+int i7 = -9 << INTM1; /* { dg-warning "requires 36 bits to represent" } */
+int i8 = -10 << INTM2; /* { dg-warning "requires 35 bits to represent" } */
+int i9 = -__INT_MAX__ << 2; /* { dg-warning "requires 34 bits to represent" }
*/
+int i10 = -__INT_MAX__ << INTM1; /* { dg-warning "requires 63 bits to
represent" } */
+
+int r1 = 1 >> INTM1;
+int r2 = 9 >> INTM1;
+int r3 = 10 >> INTM2;
+int r4 = __INT_MAX__ >> 2;
+int r5 = __INT_MAX__ >> INTM1;
+int r6 = -1 >> INTM1;
+int r7 = -9 >> INTM1;
+int r8 = -10 >> INTM2;
+int r9 = -__INT_MAX__ >> 2;
+int r10 = -__INT_MAX__ >> INTM1;
+
+unsigned u1 = 1 << INTM1;
+unsigned u2 = 9 << INTM1; /* { dg-warning "requires 36 bits to represent" } */
+unsigned u3 = 2U << INTM1;
+unsigned u4 = 9U << INTM1;
+unsigned u5 = 10U << INTM2;
+
+long long int l1 = 1LL << LLONGM1;
+long long int l2 = 9LL << LLONGM1; /* { dg-warning "requires 68 bits to
represent" } */
+long long int l3 = 10LL << LLONGM2; /* { dg-warning "requires 67 bits to
represent" } */
+long long int l4 = __LONG_LONG_MAX__ << 2; /* { dg-warning "requires 66 bits
to represent" } */
+long long int l5 = __LONG_LONG_MAX__ << LLONGM1; /* { dg-warning "requires 127
bits to represent" } */
+long long int l6 = -1LL << LLONGM1;
+long long int l7 = -9LL << LLONGM1; /* { dg-warning "requires 68 bits to
represent" } */
+long long int l8 = -10LL << LLONGM2; /* { dg-warning "requires 67 bits to
represent" } */
+long long int l9 = -__LONG_LONG_MAX__ << 2; /* { dg-warning "requires 66 bits
to represent" } */
+long long int l10 = -__LONG_LONG_MAX__ << LLONGM1; /* { dg-warning "requires
127 bits to represent" } */
+
+void
+fn (void)
+{
+ const int a = 10;
+ const __SIZE_TYPE__ b = INTM1;
+ int k1 = a << b; /* { dg-warning "requires 36 bits to represent" } */
+ int k2 = 10 << b; /* { dg-warning "requires 36 bits to represent" } */
+ int k3 = a << INTM1; /* { dg-warning "requires 36 bits to represent" } */
+}
diff --git gcc/testsuite/c-c++-common/Wshift-overflow-2.c
gcc/testsuite/c-c++-common/Wshift-overflow-2.c
index e69de29..d5115d0 100644
--- gcc/testsuite/c-c++-common/Wshift-overflow-2.c
+++ gcc/testsuite/c-c++-common/Wshift-overflow-2.c
@@ -0,0 +1,58 @@
+/* PR c++/55095 */
+/* { dg-do compile { target int32 } } */
+/* { dg-options "-O -Wno-shift-overflow" } */
+/* { dg-additional-options "-std=c++11" { target c++ } } */
+
+#define INTM1 (sizeof (int) * __CHAR_BIT__ - 1)
+#define INTM2 (sizeof (int) * __CHAR_BIT__ - 2)
+#define LLONGM1 (sizeof (long long) * __CHAR_BIT__ - 1)
+#define LLONGM2 (sizeof (long long) * __CHAR_BIT__ - 2)
+
+int i1 = 1 << INTM1;
+int i2 = 9 << INTM1;
+int i3 = 10 << INTM2;
+int i4 = __INT_MAX__ << 2;
+int i5 = __INT_MAX__ << INTM1;
+int i6 = -1 << INTM1;
+int i7 = -9 << INTM1;
+int i8 = -10 << INTM2;
+int i9 = -__INT_MAX__ << 2;
+int i10 = -__INT_MAX__ << INTM1;
+
+int r1 = 1 >> INTM1;
+int r2 = 9 >> INTM1;
+int r3 = 10 >> INTM2;
+int r4 = __INT_MAX__ >> 2;
+int r5 = __INT_MAX__ >> INTM1;
+int r6 = -1 >> INTM1;
+int r7 = -9 >> INTM1;
+int r8 = -10 >> INTM2;
+int r9 = -__INT_MAX__ >> 2;
+int r10 = -__INT_MAX__ >> INTM1;
+
+unsigned u1 = 1 << INTM1;
+unsigned u2 = 9 << INTM1;
+unsigned u3 = 2U << INTM1;
+unsigned u4 = 9U << INTM1;
+unsigned u5 = 10U << INTM2;
+
+long long int l1 = 1LL << LLONGM1;
+long long int l2 = 9LL << LLONGM1;
+long long int l3 = 10LL << LLONGM2;
+long long int l4 = __LONG_LONG_MAX__ << 2;
+long long int l5 = __LONG_LONG_MAX__ << LLONGM1;
+long long int l6 = -1LL << LLONGM1;
+long long int l7 = -9LL << LLONGM1;
+long long int l8 = -10LL << LLONGM2;
+long long int l9 = -__LONG_LONG_MAX__ << 2;
+long long int l10 = -__LONG_LONG_MAX__ << LLONGM1;
+
+void
+fn (void)
+{
+ const int a = 10;
+ const __SIZE_TYPE__ b = INTM1;
+ int k1 = a << b;
+ int k2 = 10 << b;
+ int k3 = a << INTM1;
+}
diff --git gcc/testsuite/c-c++-common/Wshift-overflow-3.c
gcc/testsuite/c-c++-common/Wshift-overflow-3.c
index e69de29..ed57d5d 100644
--- gcc/testsuite/c-c++-common/Wshift-overflow-3.c
+++ gcc/testsuite/c-c++-common/Wshift-overflow-3.c
@@ -0,0 +1,59 @@
+/* PR c++/55095 */
+/* { dg-do compile { target int32 } } */
+/* { dg-options "-O -Wshift-overflow" } */
+/* { dg-additional-options "-std=gnu90" { target c } } */
+/* { dg-additional-options "-std=c++03" { target c++ } } */
+
+#define INTM1 (sizeof (int) * __CHAR_BIT__ - 1)
+#define INTM2 (sizeof (int) * __CHAR_BIT__ - 2)
+#define LLONGM1 (sizeof (long long) * __CHAR_BIT__ - 1)
+#define LLONGM2 (sizeof (long long) * __CHAR_BIT__ - 2)
+
+int i1 = 1 << INTM1;
+int i2 = 9 << INTM1; /* { dg-warning "requires 36 bits to represent" } */
+int i3 = 10 << INTM2; /* { dg-warning "requires 35 bits to represent" } */
+int i4 = __INT_MAX__ << 2; /* { dg-warning "requires 34 bits to represent" } */
+int i5 = __INT_MAX__ << INTM1; /* { dg-warning "requires 63 bits to represent"
} */
+int i6 = -1 << INTM1;
+int i7 = -9 << INTM1; /* { dg-warning "requires 36 bits to represent" } */
+int i8 = -10 << INTM2; /* { dg-warning "requires 35 bits to represent" } */
+int i9 = -__INT_MAX__ << 2; /* { dg-warning "requires 34 bits to represent" }
*/
+int i10 = -__INT_MAX__ << INTM1; /* { dg-warning "requires 63 bits to
represent" } */
+
+int r1 = 1 >> INTM1;
+int r2 = 9 >> INTM1;
+int r3 = 10 >> INTM2;
+int r4 = __INT_MAX__ >> 2;
+int r5 = __INT_MAX__ >> INTM1;
+int r6 = -1 >> INTM1;
+int r7 = -9 >> INTM1;
+int r8 = -10 >> INTM2;
+int r9 = -__INT_MAX__ >> 2;
+int r10 = -__INT_MAX__ >> INTM1;
+
+unsigned u1 = 1 << INTM1;
+unsigned u2 = 9 << INTM1; /* { dg-warning "requires 36 bits to represent" } */
+unsigned u3 = 2U << INTM1;
+unsigned u4 = 9U << INTM1;
+unsigned u5 = 10U << INTM2;
+
+long long int l1 = 1LL << LLONGM1;
+long long int l2 = 9LL << LLONGM1; /* { dg-warning "requires 68 bits to
represent" } */
+long long int l3 = 10LL << LLONGM2; /* { dg-warning "requires 67 bits to
represent" } */
+long long int l4 = __LONG_LONG_MAX__ << 2; /* { dg-warning "requires 66 bits
to represent" } */
+long long int l5 = __LONG_LONG_MAX__ << LLONGM1; /* { dg-warning "requires 127
bits to represent" } */
+long long int l6 = -1LL << LLONGM1;
+long long int l7 = -9LL << LLONGM1; /* { dg-warning "requires 68 bits to
represent" } */
+long long int l8 = -10LL << LLONGM2; /* { dg-warning "requires 67 bits to
represent" } */
+long long int l9 = -__LONG_LONG_MAX__ << 2; /* { dg-warning "requires 66 bits
to represent" } */
+long long int l10 = -__LONG_LONG_MAX__ << LLONGM1; /* { dg-warning "requires
127 bits to represent" } */
+
+void
+fn (void)
+{
+ const int a = 10;
+ const __SIZE_TYPE__ b = INTM1;
+ int k1 = a << b; /* { dg-warning "requires 36 bits to represent" } */
+ int k2 = 10 << b; /* { dg-warning "requires 36 bits to represent" } */
+ int k3 = a << INTM1; /* { dg-warning "requires 36 bits to represent" } */
+}
diff --git gcc/testsuite/c-c++-common/Wshift-overflow-4.c
gcc/testsuite/c-c++-common/Wshift-overflow-4.c
index e69de29..92f8cf8 100644
--- gcc/testsuite/c-c++-common/Wshift-overflow-4.c
+++ gcc/testsuite/c-c++-common/Wshift-overflow-4.c
@@ -0,0 +1,59 @@
+/* PR c++/55095 */
+/* { dg-do compile { target int32 } } */
+/* { dg-options "-O" } */
+/* { dg-additional-options "-std=gnu90" { target c } } */
+/* { dg-additional-options "-std=c++03" { target c++ } } */
+
+#define INTM1 (sizeof (int) * __CHAR_BIT__ - 1)
+#define INTM2 (sizeof (int) * __CHAR_BIT__ - 2)
+#define LLONGM1 (sizeof (long long) * __CHAR_BIT__ - 1)
+#define LLONGM2 (sizeof (long long) * __CHAR_BIT__ - 2)
+
+int i1 = 1 << INTM1;
+int i2 = 9 << INTM1;
+int i3 = 10 << INTM2;
+int i4 = __INT_MAX__ << 2;
+int i5 = __INT_MAX__ << INTM1;
+int i6 = -1 << INTM1;
+int i7 = -9 << INTM1;
+int i8 = -10 << INTM2;
+int i9 = -__INT_MAX__ << 2;
+int i10 = -__INT_MAX__ << INTM1;
+
+int r1 = 1 >> INTM1;
+int r2 = 9 >> INTM1;
+int r3 = 10 >> INTM2;
+int r4 = __INT_MAX__ >> 2;
+int r5 = __INT_MAX__ >> INTM1;
+int r6 = -1 >> INTM1;
+int r7 = -9 >> INTM1;
+int r8 = -10 >> INTM2;
+int r9 = -__INT_MAX__ >> 2;
+int r10 = -__INT_MAX__ >> INTM1;
+
+unsigned u1 = 1 << INTM1;
+unsigned u2 = 9 << INTM1;
+unsigned u3 = 2U << INTM1;
+unsigned u4 = 9U << INTM1;
+unsigned u5 = 10U << INTM2;
+
+long long int l1 = 1LL << LLONGM1;
+long long int l2 = 9LL << LLONGM1;
+long long int l3 = 10LL << LLONGM2;
+long long int l4 = __LONG_LONG_MAX__ << 2;
+long long int l5 = __LONG_LONG_MAX__ << LLONGM1;
+long long int l6 = -1LL << LLONGM1;
+long long int l7 = -9LL << LLONGM1;
+long long int l8 = -10LL << LLONGM2;
+long long int l9 = -__LONG_LONG_MAX__ << 2;
+long long int l10 = -__LONG_LONG_MAX__ << LLONGM1;
+
+void
+fn (void)
+{
+ const int a = 10;
+ const __SIZE_TYPE__ b = INTM1;
+ int k1 = a << b;
+ int k2 = 10 << b;
+ int k3 = a << INTM1;
+}
diff --git gcc/testsuite/c-c++-common/Wshift-overflow-5.c
gcc/testsuite/c-c++-common/Wshift-overflow-5.c
index e69de29..c9f4643 100644
--- gcc/testsuite/c-c++-common/Wshift-overflow-5.c
+++ gcc/testsuite/c-c++-common/Wshift-overflow-5.c
@@ -0,0 +1,11 @@
+/* PR c++/55095 */
+/* { dg-do compile { target int32 } } */
+/* { dg-options "-O -Wshift-overflow=2" } */
+/* { dg-additional-options "-std=c++11" { target c++ } } */
+
+#define INTM1 (sizeof (int) * __CHAR_BIT__ - 1)
+#define LLONGM1 (sizeof (long long) * __CHAR_BIT__ - 1)
+
+int i1 = 1 << INTM1; /* { dg-warning "requires 33 bits to represent" } */
+unsigned u1 = 1 << INTM1; /* { dg-warning "requires 33 bits to represent" } */
+long long int l1 = 1LL << LLONGM1; /* { dg-warning "requires 65 bits to
represent" } */
diff --git gcc/testsuite/g++.dg/cpp1y/left-shift-1.C
gcc/testsuite/g++.dg/cpp1y/left-shift-1.C
index e69de29..a24caae 100644
--- gcc/testsuite/g++.dg/cpp1y/left-shift-1.C
+++ gcc/testsuite/g++.dg/cpp1y/left-shift-1.C
@@ -0,0 +1,11 @@
+// PR c++/55095
+// { dg-do compile { target c++14 } }
+// { dg-options "-Wshift-overflow=2" }
+// { dg-require-effective-target int32plus }
+
+#define INTM1 (sizeof (int) * __CHAR_BIT__ - 1)
+#define LLONGM1 (sizeof (long long) * __CHAR_BIT__ - 1)
+
+int i1 = 1 << INTM1;
+unsigned u1 = 1 << INTM1;
+long long int l1 = 1LL << LLONGM1;
diff --git gcc/testsuite/gcc.c-torture/execute/pr40386.c
gcc/testsuite/gcc.c-torture/execute/pr40386.c
index f39f1de..c701304 100644
--- gcc/testsuite/gcc.c-torture/execute/pr40386.c
+++ gcc/testsuite/gcc.c-torture/execute/pr40386.c
@@ -1,4 +1,4 @@
-/* { dg-options "-fno-ira-share-spill-slots" } */
+/* { dg-options "-fno-ira-share-spill-slots -Wno-shift-overflow" } */
extern void abort (void);
extern void exit (int);
diff --git gcc/testsuite/gcc.dg/c90-left-shift-2.c
gcc/testsuite/gcc.dg/c90-left-shift-2.c
index e69de29..f79ab8b 100644
--- gcc/testsuite/gcc.dg/c90-left-shift-2.c
+++ gcc/testsuite/gcc.dg/c90-left-shift-2.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-std=iso9899:1990 -pedantic-errors" } */
+
+#define INTM2 (sizeof (int) * __CHAR_BIT__ - 2)
+
+enum { A = 10 << INTM2 };
+int k = 10 << INTM2;
+
+void
+fn (int i)
+{
+ switch (i)
+ case 10 << INTM2: break;
+}
diff --git gcc/testsuite/gcc.dg/c90-left-shift-3.c
gcc/testsuite/gcc.dg/c90-left-shift-3.c
index e69de29..43942dd 100644
--- gcc/testsuite/gcc.dg/c90-left-shift-3.c
+++ gcc/testsuite/gcc.dg/c90-left-shift-3.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-std=iso9899:1990 -pedantic-errors" } */
+
+#define INTM1 (sizeof (int) * __CHAR_BIT__ - 1)
+
+enum { A = 1 << INTM1 };
+int k = 1 << INTM1;
+
+void
+fn (int i)
+{
+ switch (i)
+ case 1 << INTM1: break;
+}
diff --git gcc/testsuite/gcc.dg/c99-left-shift-2.c
gcc/testsuite/gcc.dg/c99-left-shift-2.c
index e69de29..e35786e 100644
--- gcc/testsuite/gcc.dg/c99-left-shift-2.c
+++ gcc/testsuite/gcc.dg/c99-left-shift-2.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-std=iso9899:1999 -pedantic-errors -Wno-shift-overflow" } */
+
+#define INTM2 (sizeof (int) * __CHAR_BIT__ - 2)
+
+enum { A = 10 << INTM2 }; /* { dg-error "constant expression" } */
+int k = 10 << INTM2; /* { dg-error "constant expression" } */
+
+void
+fn (int i)
+{
+ switch (i)
+ case 10 << INTM2: break; /* { dg-error "constant expression" } */
+}
diff --git gcc/testsuite/gcc.dg/c99-left-shift-3.c
gcc/testsuite/gcc.dg/c99-left-shift-3.c
index e69de29..59d0f24 100644
--- gcc/testsuite/gcc.dg/c99-left-shift-3.c
+++ gcc/testsuite/gcc.dg/c99-left-shift-3.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-std=iso9899:1999 -pedantic-errors -Wno-shift-overflow" } */
+
+#define INTM1 (sizeof (int) * __CHAR_BIT__ - 1)
+
+enum { A = 1 << INTM1 }; /* { dg-error "constant expression" } */
+int k = 1 << INTM1; /* { dg-error "constant expression" } */
+
+void
+fn (int i)
+{
+ switch (i)
+ case 1 << INTM1: break; /* { dg-error "constant expression" } */
+}
diff --git gcc/testsuite/gcc.dg/pr40501.c gcc/testsuite/gcc.dg/pr40501.c
index e6ce217..7610a20 100644
--- gcc/testsuite/gcc.dg/pr40501.c
+++ gcc/testsuite/gcc.dg/pr40501.c
@@ -1,5 +1,5 @@
/* { dg-do compile { target alpha*-*-* ia64*-*-* i?86-*-* x86_64-*-* s390x-*-*
} } */
-/* { dg-options "-O2" } */
+/* { dg-options "-O2 -Wno-shift-overflow" } */
/* { dg-require-effective-target lp64 } */
/* PR middle-end/40501 */
diff --git gcc/testsuite/gcc.dg/vect/pr33373.c
gcc/testsuite/gcc.dg/vect/pr33373.c
index 8da4371..efba2ab 100644
--- gcc/testsuite/gcc.dg/vect/pr33373.c
+++ gcc/testsuite/gcc.dg/vect/pr33373.c
@@ -1,3 +1,4 @@
+/* { dg-options "-Wno-shift-overflow" } */
/* { dg-do compile } */
void DOSMEM_FillIsrTable(int*isr) {
int i;
diff --git gcc/testsuite/gcc.dg/vect/vect-shift-2-big-array.c
gcc/testsuite/gcc.dg/vect/vect-shift-2-big-array.c
index 46909ca..85ff0e0 100644
--- gcc/testsuite/gcc.dg/vect/vect-shift-2-big-array.c
+++ gcc/testsuite/gcc.dg/vect/vect-shift-2-big-array.c
@@ -1,3 +1,4 @@
+/* { dg-options "-Wno-shift-overflow" } */
/* { dg-require-effective-target vect_shift } */
/* { dg-require-effective-target vect_int } */
/* Check the standard integer types for left and right shifts to see if the
diff --git gcc/testsuite/gcc.dg/vect/vect-shift-2.c
gcc/testsuite/gcc.dg/vect/vect-shift-2.c
index 68186db..6199cd6 100644
--- gcc/testsuite/gcc.dg/vect/vect-shift-2.c
+++ gcc/testsuite/gcc.dg/vect/vect-shift-2.c
@@ -1,3 +1,4 @@
+/* { dg-options "-Wno-shift-overflow" } */
/* { dg-require-effective-target vect_shift } */
/* { dg-require-effective-target vect_int } */
/* Check the standard integer types for left and right shifts to see if the
Marek
