[Bug analyzer/94365] false positive leak when using container_of-like constructs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94365 dimitri at ouroboros dot rocks changed: What|Removed |Added CC||dimitri at ouroboros dot rocks --- Comment #1 from dimitri at ouroboros dot rocks --- Thanks for filing this one. We're using a double-linked-list implementation which also has this construct using offsetof and are also seeing false positives in these parts of the code. I thought the analyzer may have trouble with the list pointers, but I think it will actually be the offsetof that is causing it.
[Bug tree-optimization/101039] New: Some simple fold_cond_expr_with_comparison with CMP 0 is not simplified
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101039
Bug ID: 101039
Summary: Some simple fold_cond_expr_with_comparison with CMP 0
is not simplified
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Take at -O2:
int f0(int A)
{
// A == 0? A : -Asame as -A
if (A == 0) return A;
return -A;
}
int f1(int A)
{
// A != 0? A : -Asame as A
if (A != 0) return A;
return -A;
}
int f2(int A)
{
// A >= 0? A : -Asame as abs (A)
if (A >= 0) return A;
return -A;
}
int f3(int A)
{
// A > 0? A : -Asame as abs (A)
if (A > 0) return A;
return -A;
}
int f4(int A)
{
// A <= 0? A : -Asame as -abs (A)
if (A <= 0) return A;
return -A;
}
int f5(int A)
{
// A < 0? A : -Asame as -abs (A)
if (A < 0) return A;
return -A;
}
-- CUT ---
Only f1-f3 are optimized at the gimple level. f0, f4, f5 are not.
With -Dint=float -Ofast, only f0 is not optimized but note f1 takes until
*.phiopt3 be optimized; and unlike int, f4 and f5 are optimized in phiopt2.
Note phiopt1 is still confused by predictor but I think there might be another
bug for that.
[Bug c++/101040] New: [11 Regression] Internal compiler error: in get_or_insert_ctor_field, at cp/constexpr.c:3571
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101040
Bug ID: 101040
Summary: [11 Regression] Internal compiler error: in
get_or_insert_ctor_field, at cp/constexpr.c:3571
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: git at foonathan dot net
Target Milestone: ---
Minimal repro: https://godbolt.org/z/n71dhjPox
```
// This class has to be empty.
struct empty
{};
// This class has to be empty.
struct single
{
// This member has to be no_unique_address.
[[no_unique_address]] empty obj;
};
// This class has to be empty and derived from single.
struct derived : single
{
// This constructor has to be constexpr and take a forwarding reference.
template
constexpr derived(Arg&& arg) : single{arg}
{}
};
auto obj = derived{empty{}};
```
Fails on GCC 11.1 and trunk:
```
source>:21:27: in 'constexpr' expansion of 'derived(empty())'
:21:27: internal compiler error: in get_or_insert_ctor_field, at
cp/constexpr.c:3571
21 | auto obj = derived{empty{}};
| ^
0x1d322a9 internal_error(char const*, ...)
???:0
0x71fc09 fancy_abort(char const*, int, char const*)
???:0
0xa58de0 store_init_value(tree_node*, tree_node*, vec**, int)
???:0
0x818a14 cp_finish_decl(tree_node*, tree_node*, bool, tree_node*, int)
???:0
0x94812d c_parse_file()
???:0
0xacb002 c_common_parse_file()
???:0
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See
[Bug middle-end/67809] Empty pointer-chasing loops aren't optimized out
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67809 Gareth Lloyd changed: What|Removed |Added CC||gar...@ignition-web.co.uk --- Comment #11 from Gareth Lloyd --- Looks like as of GCC 10.1 this optimisation exists This bug can be closed?
[Bug target/101041] New: z13: Inefficient handling of vector register passed to function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101041
Bug ID: 101041
Summary: z13: Inefficient handling of vector register passed to
function
Product: gcc
Version: 8.3.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: jens.seifert at de dot ibm.com
Target Milestone: ---
#include
vector unsigned long long mul64(vector unsigned long long a, vector unsigned
long long b)
{
return a * b;
}
creates:
_Z5mul64Dv2_yS_:
.LFB9:
.cfi_startproc
ldgr%f4,%r15
.cfi_register 15, 18
lay %r15,-192(%r15)
.cfi_def_cfa_offset 352
vst %v24,160(%r15),3
vst %v26,176(%r15),3
lg %r2,160(%r15)
lg %r1,176(%r15)
lgr %r4,%r2
lg %r0,168(%r15)
lgr %r2,%r1
lg %r1,184(%r15)
lgr %r5,%r0
lgr %r3,%r1
vlvgp %v2,%r4,%r5
vlvgp %v0,%r2,%r3
vlgvg %r4,%v2,0
vlgvg %r1,%v2,1
vlgvg %r2,%v0,0
vlgvg %r3,%v0,1
msgr%r2,%r4
msgr%r1,%r3
lgdr%r15,%f4
.cfi_restore 15
.cfi_def_cfa_offset 160
vlvgp %v24,%r2,%r1
br %r14
Store to stack of v24,v26, then lg+lgr for all 4 parts, then constructing new
vector register v0 and v2 and then extract the 4 elements again using vlgvg.
Expected 4 * vlgvg + 2 * msgr + vlvgp
[Bug c/101042] New: Bogus -Wstringop-overread with 11.1.0 and -O1 because of a call to printf _after_ assertions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101042
Bug ID: 101042
Summary: Bogus -Wstringop-overread with 11.1.0 and -O1 because
of a call to printf _after_ assertions
Product: gcc
Version: 11.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: ypsah+6a11ea7d-369c-4db1-b3f4-60ced987a559 at devyard dot
org
Target Milestone: ---
Created attachment 50989
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50989&action=edit
reproducer.c
Hi,
It looks like printf-ing a pointer after running assertions on it throws gcc 11
off:
#include
#include
#include
#include
enum field_type {
INTEGER,
STRING,
};
struct field {
enum field_type type;
union {
int integer;
const char *string;
};
};
int
main()
{
const struct field FIELD = {
.type = INTEGER,
.integer = 1,
};
struct field *field = calloc(1, sizeof(struct field));
assert(field);
assert(field->type == FIELD.type);
printf("field = %p\n", field);
switch (field->type) {
case STRING:
assert(strcmp(field->string, FIELD.string) == 0);
break;
default:
break;
}
free(field);
return 0;
}
$ gcc -Werror -O0 reproducer.c # <== Runs fine
$ gcc -Werror -O1 reproducer.c
In file included from reproducer.c:1:
reproducer.c: In function ‘main’:
reproducer.c:34:16: error: ‘strcmp’ reading 1 or more bytes from a region of
size 0 [-Werror=stringop-overread]
34 | assert(strcmp(field->string, FIELD.string) == 0);
|^~~
cc1: all warnings being treated as errors
Any optimization level above 0 yields the warning.
If you remove the printf() statement, or place it before one of the two
assert(), the warning goes away.
Downgrading to 10.2.0 also fixes the issue.
[Bug c++/101029] [10/11/12 regression] unexpected error: non-constant condition for static assertion in gcc 10/11, but not 9 (clang also fine)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101029 --- Comment #6 from CVS Commits --- The master branch has been updated by Jason Merrill : https://gcc.gnu.org/g:08e1ff9d6e5a419d5b4a60c077df549e81601d9b commit r12-1404-g08e1ff9d6e5a419d5b4a60c077df549e81601d9b Author: Jason Merrill Date: Fri Jun 11 16:55:30 2021 -0400 c++: constexpr and array[0] [PR101029] build_vec_init_elt exits early if we're initializing a zero-element array, so build_vec_init needs to do the same to avoid trying to instantiate things after we've already started throwing important bits away. PR c++/101029 gcc/cp/ChangeLog: * init.c (build_vec_init): Shortcut [0] case. gcc/testsuite/ChangeLog: * g++.dg/ext/array4.C: New test.
[Bug tree-optimization/101042] Bogus -Wstringop-overread with 11.1.0 and -O1 because of a call to printf _after_ assertions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101042 Andrew Pinski changed: What|Removed |Added Component|c |tree-optimization --- Comment #1 from Andrew Pinski --- The probelm is GCC does not know that printf cannot change field->type.
[Bug c/39985] Type qualifiers not actually ignored on function return type
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=39985 Martin Uecker changed: What|Removed |Added CC||muecker at gwdg dot de --- Comment #10 from Martin Uecker --- It seems this is fixed in 11.1: https://gcc.godbolt.org/z/nMqz8sG1v
[Bug c++/101043] New: ICE in check_noexcept_r for lambda conditional noexcept via requires expression
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101043
Bug ID: 101043
Summary: ICE in check_noexcept_r for lambda conditional
noexcept via requires expression
Product: gcc
Version: 10.3.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: jbassett271 at gmail dot com
Target Milestone: ---
GCC has an internal compiler error for requires expressions inside the noexcept
clause of a lambda inside a templated function:
https://godbolt.org/z/oWhq9sf8M
template
struct set {
bool contains(T const&) const { return true; }
};
template
void intersect(set const& lhs, set const& rhs) {
auto f = [&](T1&& _1) noexcept(requires {
{ rhs.contains(_1) } noexcept;
}) {
return rhs.contains(_1);
};
}
int main() {
set lhs;
set rhs;
intersect(lhs, rhs);
}
Error message:
: In instantiation of 'void intersect(const set&, const set&)
[with T = int]':
:18:21: required from here
:9:7: internal compiler error: in check_noexcept_r, at cp/except.c:1123
9 | { rhs.contains(_1) } noexcept;
| ~~^~~
Please submit a full bug report,
with preprocessed source if appropriate.
See
[Bug fortran/100683] Array initialization refuses valid
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100683 --- Comment #5 from José Rui Faustino de Sousa --- I am having trouble reproducing this. Can you provide some more detail on your setup? Best regards, José Rui
[Bug rtl-optimization/101044] New: -ABS(A) produces two neg instructions
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101044
Bug ID: 101044
Summary: -ABS(A) produces two neg instructions
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Target: x86_64-linux-gnu
Take:
int f4(int A)
{
return A <= 0? A : -A;
}
int f5(int A)
{
return A < 0? A : -A;
}
int f2(int A)
{
A = A < 0 ? -A : A;
return -A;
}
CUT ---
On x86_64 we get two neg for each of these functions now, we used to get none
sometime ago.
Right now we get for each of them:
movl%edi, %eax
negl%eax
cmovs %edi, %eax
negl%eax
- CUT ---
Note aarch64 seems to be fine:
cmp w0, 0
csneg w0, w0, w0, lt
