Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
On Wed, Jul 22, 2015 at 07:48:47AM -0500, Segher Boessenkool wrote:
vmx.exp sets a bunch of options and the test overrides that now. Options
like -maltivec are pretty important for this test to work -- it #includes
altivec.h, which does #error unless -maltivec is set, and things go downhill
from that. unpack-be-order.c works, unpack.c blows up.
Ah, right.
Does your compiler maybe default to -maltivec?
I suppose -- I didn't see any failures on cfarm 112, but I was able to
reproduce the unpack.c fail on cfarm 110. Turned out I should've used
dg-additional-options. Thanks.
Tested vmx.exp on powerpc64-unknown-linux-gnu, applying to trunk.
2015-07-22 Marek Polacek pola...@redhat.com
* gcc.dg/vmx/unpack.c: Use dg-additional-options rather than
dg-options.
diff --git gcc/testsuite/gcc.dg/vmx/unpack.c gcc/testsuite/gcc.dg/vmx/unpack.c
index e71a5a6..b3ec93a 100644
--- gcc/testsuite/gcc.dg/vmx/unpack.c
+++ gcc/testsuite/gcc.dg/vmx/unpack.c
@@ -1,4 +1,4 @@
-/* { dg-options -Wno-shift-overflow } */
+/* { dg-additional-options -Wno-shift-overflow } */
#include harness.h
Marek
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
On Wed, Jul 22, 2015 at 08:35:12AM -0400, David Edelsohn wrote:
On Tue, Jul 21, 2015 at 5:59 AM, Marek Polacek pola...@redhat.com wrote:
On Mon, Jul 20, 2015 at 04:23:08PM -0400, David Edelsohn wrote:
This seems to have caused a number of new failures in the PPC
testsuite for vmx/unpack.
Sorry about that. Should be fixed with this patch I'm about to commit.
2015-07-21 Marek Polacek pola...@redhat.com
* gcc.dg/vmx/unpack-be-order.c: Use -Wno-shift-overflow.
* gcc.dg/vmx/unpack.c: Likewise.
This doesn't fully fix the failures.
Ouch. What other failures do you see? I've tried the patch on ppc64-linux
and didn't see any others.
It'd be very weird to see -Wshift-overflow warnings when -Wno-shift-overflow
is in effect.
--- gcc/testsuite/gcc.dg/vmx/unpack.c
+++ gcc/testsuite/gcc.dg/vmx/unpack.c
@@ -1,3 +1,5 @@
+/* { dg-options -Wno-shift-overflow } */
+
Should this be dg-additional-options ?
I did what was in gcc.dg/vmx/unpack-be-order.c, i.e. dg-options. Or does
using dg-additional-options help?
Marek
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
On Wed, Jul 22, 2015 at 02:39:14PM +0200, Marek Polacek wrote: On Wed, Jul 22, 2015 at 08:35:12AM -0400, David Edelsohn wrote: On Tue, Jul 21, 2015 at 5:59 AM, Marek Polacek pola...@redhat.com wrote: On Mon, Jul 20, 2015 at 04:23:08PM -0400, David Edelsohn wrote: This seems to have caused a number of new failures in the PPC testsuite for vmx/unpack. Sorry about that. Should be fixed with this patch I'm about to commit. 2015-07-21 Marek Polacek pola...@redhat.com * gcc.dg/vmx/unpack-be-order.c: Use -Wno-shift-overflow. * gcc.dg/vmx/unpack.c: Likewise. This doesn't fully fix the failures. Ouch. What other failures do you see? I've tried the patch on ppc64-linux and didn't see any others. vmx.exp sets a bunch of options and the test overrides that now. Options like -maltivec are pretty important for this test to work -- it #includes altivec.h, which does #error unless -maltivec is set, and things go downhill from that. unpack-be-order.c works, unpack.c blows up. Does your compiler maybe default to -maltivec? Segher
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
On Tue, Jul 21, 2015 at 5:59 AM, Marek Polacek pola...@redhat.com wrote:
On Mon, Jul 20, 2015 at 04:23:08PM -0400, David Edelsohn wrote:
This seems to have caused a number of new failures in the PPC
testsuite for vmx/unpack.
Sorry about that. Should be fixed with this patch I'm about to commit.
2015-07-21 Marek Polacek pola...@redhat.com
* gcc.dg/vmx/unpack-be-order.c: Use -Wno-shift-overflow.
* gcc.dg/vmx/unpack.c: Likewise.
This doesn't fully fix the failures.
* gcc.target/powerpc/quad-atomic.c: Likewise.
diff --git gcc/testsuite/gcc.dg/vmx/unpack.c gcc/testsuite/gcc.dg/vmx/unpack.c
index 3c13163..e71a5a6 100644
--- gcc/testsuite/gcc.dg/vmx/unpack.c
+++ gcc/testsuite/gcc.dg/vmx/unpack.c
@@ -1,3 +1,5 @@
+/* { dg-options -Wno-shift-overflow } */
+
Should this be dg-additional-options ?
#include harness.h
#define BIG 4294967295
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
On Mon, Jul 20, 2015 at 04:23:08PM -0400, David Edelsohn wrote:
This seems to have caused a number of new failures in the PPC
testsuite for vmx/unpack.
Sorry about that. Should be fixed with this patch I'm about to commit.
2015-07-21 Marek Polacek pola...@redhat.com
* gcc.dg/vmx/unpack-be-order.c: Use -Wno-shift-overflow.
* gcc.dg/vmx/unpack.c: Likewise.
* gcc.target/powerpc/quad-atomic.c: Likewise.
diff --git gcc/testsuite/gcc.dg/vmx/unpack-be-order.c
gcc/testsuite/gcc.dg/vmx/unpack-be-order.c
index e174433..6eb98f4 100644
--- gcc/testsuite/gcc.dg/vmx/unpack-be-order.c
+++ gcc/testsuite/gcc.dg/vmx/unpack-be-order.c
@@ -1,4 +1,4 @@
-/* { dg-options -maltivec=be -mabi=altivec -std=gnu99 -mno-vsx } */
+/* { dg-options -maltivec=be -mabi=altivec -std=gnu99 -mno-vsx
-Wno-shift-overflow } */
#include harness.h
diff --git gcc/testsuite/gcc.dg/vmx/unpack.c gcc/testsuite/gcc.dg/vmx/unpack.c
index 3c13163..e71a5a6 100644
--- gcc/testsuite/gcc.dg/vmx/unpack.c
+++ gcc/testsuite/gcc.dg/vmx/unpack.c
@@ -1,3 +1,5 @@
+/* { dg-options -Wno-shift-overflow } */
+
#include harness.h
#define BIG 4294967295
diff --git gcc/testsuite/gcc.target/powerpc/quad-atomic.c
gcc/testsuite/gcc.target/powerpc/quad-atomic.c
index 0d7089b..dc0e3a8 100644
--- gcc/testsuite/gcc.target/powerpc/quad-atomic.c
+++ gcc/testsuite/gcc.target/powerpc/quad-atomic.c
@@ -3,7 +3,7 @@
/* { dg-skip-if { powerpc*-*-*spe* } { * } { } } */
/* { dg-require-effective-target p8vector_hw } */
/* { dg-skip-if do not override -mcpu { powerpc*-*-* } { -mcpu=* } {
-mcpu=power8 } } */
-/* { dg-options -mcpu=power8 -O2 } */
+/* { dg-options -mcpu=power8 -O2 -Wno-shift-overflow } */
/* Test whether we get the right bits for quad word atomic instructions. */
#include stdlib.h
Marek
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
On Fri, Jul 17, 2015 at 03:51:33PM -0600, Jeff Law wrote: I'll approve the C++ parts given how simple they are :-) Thanks, I've committed the patch now after another regtest/bootstrap. Marek
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
This seems to have caused a number of new failures in the PPC testsuite for vmx/unpack. - David
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
Ping^6. On Fri, Jul 10, 2015 at 03:23:43PM +0200, Marek Polacek wrote: Ping^5. On Fri, Jul 03, 2015 at 09:42:39AM +0200, Marek Polacek wrote: Ping^4. On Fri, Jun 26, 2015 at 10:08:51AM +0200, Marek Polacek wrote: I'm pinging the C++ parts. On Fri, Jun 19, 2015 at 12:44:36PM +0200, Marek Polacek wrote: Ping. On Fri, Jun 12, 2015 at 11:07:29AM +0200, Marek Polacek wrote: Ping. On Fri, Jun 05, 2015 at 10:55:08AM +0200, Marek Polacek wrote: On Thu, Jun 04, 2015 at 09:04:19PM +, Joseph Myers wrote: The C changes are OK. Jason, do you want to approve the C++ parts? Marek
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
On 07/17/2015 02:09 AM, Marek Polacek wrote: Ping^6. On Fri, Jul 10, 2015 at 03:23:43PM +0200, Marek Polacek wrote: Ping^5. On Fri, Jul 03, 2015 at 09:42:39AM +0200, Marek Polacek wrote: Ping^4. On Fri, Jun 26, 2015 at 10:08:51AM +0200, Marek Polacek wrote: I'm pinging the C++ parts. On Fri, Jun 19, 2015 at 12:44:36PM +0200, Marek Polacek wrote: Ping. On Fri, Jun 12, 2015 at 11:07:29AM +0200, Marek Polacek wrote: Ping. On Fri, Jun 05, 2015 at 10:55:08AM +0200, Marek Polacek wrote: On Thu, Jun 04, 2015 at 09:04:19PM +, Joseph Myers wrote: The C changes are OK. Jason, do you want to approve the C++ parts? I'll approve the C++ parts given how simple they are :-) jeff
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
Ping^5. On Fri, Jul 03, 2015 at 09:42:39AM +0200, Marek Polacek wrote: Ping^4. On Fri, Jun 26, 2015 at 10:08:51AM +0200, Marek Polacek wrote: I'm pinging the C++ parts. On Fri, Jun 19, 2015 at 12:44:36PM +0200, Marek Polacek wrote: Ping. On Fri, Jun 12, 2015 at 11:07:29AM +0200, Marek Polacek wrote: Ping. On Fri, Jun 05, 2015 at 10:55:08AM +0200, Marek Polacek wrote: On Thu, Jun 04, 2015 at 09:04:19PM +, Joseph Myers wrote: The C changes are OK. Jason, do you want to approve the C++ parts? Marek
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
Ping^4. On Fri, Jun 26, 2015 at 10:08:51AM +0200, Marek Polacek wrote: I'm pinging the C++ parts. On Fri, Jun 19, 2015 at 12:44:36PM +0200, Marek Polacek wrote: Ping. On Fri, Jun 12, 2015 at 11:07:29AM +0200, Marek Polacek wrote: Ping. On Fri, Jun 05, 2015 at 10:55:08AM +0200, Marek Polacek wrote: On Thu, Jun 04, 2015 at 09:04:19PM +, Joseph Myers wrote: The C changes are OK. Jason, do you want to approve the C++ parts? Marek
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
I'm pinging the C++ parts. On Fri, Jun 19, 2015 at 12:44:36PM +0200, Marek Polacek wrote: Ping. On Fri, Jun 12, 2015 at 11:07:29AM +0200, Marek Polacek wrote: Ping. On Fri, Jun 05, 2015 at 10:55:08AM +0200, Marek Polacek wrote: On Thu, Jun 04, 2015 at 09:04:19PM +, Joseph Myers wrote: The C changes are OK. Jason, do you want to approve the C++ parts? Marek
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
Ping. On Fri, Jun 12, 2015 at 11:07:29AM +0200, Marek Polacek wrote: Ping. On Fri, Jun 05, 2015 at 10:55:08AM +0200, Marek Polacek wrote: On Thu, Jun 04, 2015 at 09:04:19PM +, Joseph Myers wrote: The C changes are OK. Jason, do you want to approve the C++ parts? Marek
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
Ping. On Fri, Jun 05, 2015 at 10:55:08AM +0200, Marek Polacek wrote: On Thu, Jun 04, 2015 at 09:04:19PM +, Joseph Myers wrote: The C changes are OK. Jason, do you want to approve the C++ parts? Thanks, Marek
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
On Thu, Jun 04, 2015 at 09:04:19PM +, Joseph Myers wrote: The C changes are OK. Jason, do you want to approve the C++ parts? Thanks, Marek
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
On Wed, 3 Jun 2015, Marek Polacek wrote:
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?
The C changes are OK.
--
Joseph S. Myers
jos...@codesourcery.com
Re: [C/C++ PATCH] Implement -Wshift-overflow (PR c++/55095) (take 3)
On Tue, Jun 02, 2015 at 09:25:32PM +0200, Marek Polacek wrote:
On Fri, May 29, 2015 at 08:49:58PM +, 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
