[Bug tree-optimization/82703] Wrong addition of std::array components with -O2 -ftree-loop-vectorize -ftree-slp-vectorize (works fine with -O2)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82703 --- Comment #2 from Frédéric Bron --- Created attachment 42465 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42465=edit save-temps for g++ 7.2.0
[Bug tree-optimization/82703] Wrong addition of std::array components with -O2 -ftree-loop-vectorize -ftree-slp-vectorize (works fine with -O2)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82703 --- Comment #1 from Frédéric Bron --- Created attachment 42464 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42464=edit save-temps for g++ 7.2.1
[Bug tree-optimization/82703] New: Wrong addition of std::array components with -O2 -ftree-loop-vectorize -ftree-slp-vectorize (works fine with -O2)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82703 Bug ID: 82703 Summary: Wrong addition of std::array components with -O2 -ftree-loop-vectorize -ftree-slp-vectorize (works fine with -O2) Product: gcc Version: 7.2.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: frederic.bron at m4x dot org Target Milestone: --- Created attachment 42463 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42463=edit Minimal example to reproduce the bug The small program attached to this message should always pass, i.e. not print any error. This is the case with -O2. This is also the case with clang++ 4.0.1 with -O3. However with g++ and "-O2 -ftree-loop-vectorize -ftree-slp-vectorize", v3[1] is 2.0 instead of 4.0. Note that if I change double to int, long, long long, float or long double, I have no error. Also if I do not construct Array from int[3] but from double[3], it works and if I remove a useless line, it works... Tested on linux Fedora 26 x86_64 with g++ 7.2.0 and 7.2.1 on westmere, broadwell, skylake. To reproduce failure: g++ -O2 -g -std=c++14 bug.cpp -ftree-loop-vectorize -ftree-slp-vectorize && ./a.out g++ 7.2.0 that shows the bug: Using built-in specs. COLLECT_GCC=g++-7.2.0 COLLECT_LTO_WRAPPER=/softs/gcc-7.2.0/libexec/gcc/x86_64-pc-linux-gnu/7.2.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: /softs/build/gcc-7.2.0/configure --prefix=/softs/gcc-7.2.0 --program-suffix=-7.2.0 --with-gmp-include=/softs/gmp-6.1.2/include --with-gmp-lib=/softs/gmp-6.1.2/lib --with-mpfr-include=/softs/mpfr-3.1.5/include --with-mpfr-lib=/softs/mpfr-3.1.5/lib --with-mpc-include=/softs/mpc-1.0.3/include --with-mpc-lib=/softs/mpc-1.0.3/lib --with-isl-include=/softs/isl-0.16.1/include --with-isl-lib=/softs/isl-0.16.1/lib --disable-isl-version-check --enable-lto --enable-nls --disable-multilib Thread model: posix gcc version 7.2.0 (GCC) g++ 7.2.1 that shows the bug: Using built-in specs. COLLECT_GCC=g++ COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/7/lto-wrapper OFFLOAD_TARGET_NAMES=nvptx-none OFFLOAD_TARGET_DEFAULT=1 Target: x86_64-redhat-linux Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,objc,obj-c++,fortran,ada,go,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl --enable-libmpx --enable-offload-targets=nvptx-none --without-cuda-driver --enable-gnu-indirect-function --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux Thread model: posix gcc version 7.2.1 20170915 (Red Hat 7.2.1-2) (GCC)
[Bug c++/49812] New: strange return type for built-in operator++(int, int)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49812
Summary: strange return type for built-in operator++(int, int)
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: frederic.b...@m4x.org
The following code attempts to detect if operator++ returns void or not.
The program writes true (meaning that operator++ returns void) instead of
false.
msvc 10 and icpc 12.0 are right in writing false.
The standard states in 13.6/3 (Built-in operators):
For every pair (T, VQ), where T is an arithmetic type, and VQ is
either volatile
or empty, there exist candidate operator functions of the form
VQ T operator++(VQ T);
T operator++(VQ T, int);
That means that for an int volatile variable the corresponding built-in
operator should be:
int operator++(int volatile , int);
which should bind well with operator,(const int, returns_void_t).
#include iostream
#include iomanip
namespace detail {
typedef char yes_type;
struct no_type { char padding[8]; };
struct returns_void_t {};
static yes_type returns_void(returns_void_t);
static no_type returns_void(int);
}
template typename T int operator,(const T, ::detail::returns_void_t);
template typename T int operator,(const volatile T,
::detail::returns_void_t);
#define RETURNS_VOID(Expr)\
sizeof(::detail::yes_type)\
==\
sizeof(::detail::returns_void(((Expr), ::detail::returns_void_t(
int main() {
int volatile one_int_volatile;
std::coutstd::boolalphaRETURNS_VOID:
(RETURNS_VOID((one_int_volatile++)))'\n';
return 0;
}
[Bug c++/49812] strange return type for built-in operator++(int, int)
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49812 --- Comment #1 from Frédéric Bron frederic.bron at m4x dot org 2011-07-22 08:58:31 UTC --- Created attachment 24809 -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=24809 program that fails This program should write false but writes true.
[Bug c++/49462] New: comparison of const bool and pointer does not yield an error
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49462 Summary: comparison of const bool and pointer does not yield an error Product: gcc Version: 4.5.3 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassig...@gcc.gnu.org ReportedBy: frederic.b...@m4x.org The following code should produce the error ISO C++ forbids comparison between pointer and integer when compiled with g++ -std=c++98 -pedantic-errors. When the bool is not const or volatile of const volatile, the error is produced. Only when bool is only const, the error is not produced. Same problem with all comparison operators ==, !=, , =, , =. int * pi=0; bool const b=0; pi==b; b==pi;
