[Bug c++/96511] New: Incorrect placement-new warning
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96511
Bug ID: 96511
Summary: Incorrect placement-new warning
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mserdarsanli at gmail dot com
Target Milestone: ---
Below code causes the warning in the last line, which seems to be incorrect. It
affects all versions starting from GCC 8
Compiler explorer: https://godbolt.org/z/xhf6cr
#include
struct Foo {
Foo() = default;
Foo(int _a) : a(_a) {}
int a = 0;
};
void f()
{
Foo arr[2];
new (arr) Foo(10); // ok
new (arr + 0) Foo(10); // ok
new (&arr[0]) Foo(10); // ok
new (&arr[1]) Foo(15); // ok
new (arr + 1) Foo(15); // warning: placement new constructing an object of
type 'Foo' and size '4' in a region of type 'Foo [2]' and size '0'
[-Wplacement-new=]
}
[Bug tree-optimization/92180] New: Missed optimization on casting __builtin_ia32_rdtsc result to int32
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92180
Bug ID: 92180
Summary: Missed optimization on casting __builtin_ia32_rdtsc
result to int32
Product: gcc
Version: 9.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: mserdarsanli at gmail dot com
Target Milestone: ---
Link: https://godbolt.org/z/wcIN0a
#include
uint32_t foo1() {
return __builtin_ia32_rdtsc();
}
uint64_t foo2() {
return __builtin_ia32_rdtsc();
}
Generates assembly:
foo1():
rdtsc
sal rdx, 32
or rax, rdx
ret
foo2():
rdtsc
sal rdx, 32
or rax, rdx
ret
While clang generates better code for foo1
foo1(): # @foo1()
rdtsc
ret
[Bug tree-optimization/91409] New: Missed optimization on `labels as values` expression
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91409 Bug ID: 91409 Summary: Missed optimization on `labels as values` expression Product: gcc Version: 9.1.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: mserdarsanli at gmail dot com Target Milestone: --- I recently posted about this on SO, but it did not gain much traction: https://stackoverflow.com/questions/55987401/gcc-clang-labels-as-values-computing-offsets-at-runtime The missed optimization is when using `labels as values` feature and computing address difference. The expression `&&label2 - &&label1` generates code that does the subtraction on runtime, while it might be possible to compute it on compile time. Godbolt link: https://godbolt.org/z/zZdFYo
[Bug tree-optimization/91019] New: Missed optimization on sequential memcpy calls
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91019
Bug ID: 91019
Summary: Missed optimization on sequential memcpy calls
Product: gcc
Version: 9.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: mserdarsanli at gmail dot com
Target Milestone: ---
#include
#include
void encode_v1(uint8_t *buf, uint64_t a1, uint16_t a2) {
memcpy(buf, &a1, 6);
memcpy(buf+6, &a2, 2);
}
void encode_v2(uint8_t *buf, uint64_t a1, uint16_t a2) {
memcpy(buf, &a1, 8);
memcpy(buf+6, &a2, 2);
}
Two functions above should be equivalent, packing arguments into buffer.
`encode_v1` copies 6 bytes, then 2 bytes.
`encode_v2` copies 8 bytes, then replaces last two bytes.
Functionally they are the same, while v2 generates better assembly.
This is the assembly with -O3 (https://godbolt.org/z/i6TMiY)
encode_v1(unsigned char*, unsigned long, unsigned short):
mov eax, esi
shr rsi, 32
mov WORD PTR [rdi+6], dx
mov DWORD PTR [rdi], eax
mov WORD PTR [rdi+4], si
ret
encode_v2(unsigned char*, unsigned long, unsigned short):
mov QWORD PTR [rdi], rsi
mov WORD PTR [rdi+6], dx
ret
[Bug middle-end/54202] Overeager warning about freeing non-heap objects
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54202
Serdar Sanli changed:
What|Removed |Added
CC||mserdarsanli at gmail dot com
--- Comment #9 from Serdar Sanli ---
A simpler example not involving any globals, causing Wfree-nonheap-object
warning since GCC11
https://godbolt.org/z/MYn1zrjE4
===
struct Foo {
void allocate(int n);
void deallocate();
int *_data;
};
void Foo::allocate(int n) {
_data = new int[n] - 1;
}
void Foo::deallocate() {
delete[] (_data+1);
}
[Bug c++/108587] New: `decltype(x) x;` in struct declaration causes "changes meaning of" error
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108587
Bug ID: 108587
Summary: `decltype(x) x;` in struct declaration causes "changes
meaning of" error
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mserdarsanli at gmail dot com
Target Milestone: ---
Godbolt link: https://godbolt.org/z/rjEGPKcE7
void fine() {
int x;
struct {
int x;
} v = {
.x = x,
};
}
void not_fine() {
int x;
struct {
decltype(x) x; // error: declaration of 'int not_fine()x' changes meaning of 'x' [-fpermissive]
} v = {
.x = x,
};
}
[Bug c++/108597] New: internal compiler error with -Wduplicated-cond
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108597
Bug ID: 108597
Summary: internal compiler error with -Wduplicated-cond
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mserdarsanli at gmail dot com
Target Milestone: ---
https://godbolt.org/z/Kdvd5hzYK
compile below with -Wduplicated-cond and it will crash
template
struct MyStruct {
void check(int &x) {
if (&x == &_a) {
} else if (&x == &_b) {
}
}
int _a;
int _b;
};
[Bug c++/108597] internal compiler error with -Wduplicated-cond
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108597 --- Comment #1 from Serdar Sanli --- stacktrace from my gcc 12.2.0: 0xe2534f crash_signal /root/source/gcc-12.2.0/gcc/toplev.cc:322 0xb0f049 location_wrapper_p(tree_node const*) /root/source/gcc-12.2.0/gcc/tree.h:4160 0xb0f049 tree_strip_any_location_wrapper(tree_node*) /root/source/gcc-12.2.0/gcc/tree.h:4172 0xb0f049 operand_compare::operand_equal_p(tree_node const*, tree_node const*, unsigned int) /root/source/gcc-12.2.0/gcc/fold-const.cc:2987 0xb100fb operand_compare::operand_equal_p(tree_node const*, tree_node const*, unsigned int) /root/source/gcc-12.2.0/gcc/fold-const.cc:3363 0xb0f3f1 operand_compare::operand_equal_p(tree_node const*, tree_node const*, unsigned int) /root/source/gcc-12.2.0/gcc/fold-const.cc:3227 0x9a6f07 warn_duplicated_cond_add_or_warn(unsigned int, tree_node*, vec**) /root/source/gcc-12.2.0/gcc/c-family/c-warn.cc:2537 0x894e18 cp_parser_selection_statement /root/source/gcc-12.2.0/gcc/cp/parser.cc:13108 0x86f5d5 cp_parser_statement /root/source/gcc-12.2.0/gcc/cp/parser.cc:12296 0x893fe1 cp_parser_implicitly_scoped_statement /root/source/gcc-12.2.0/gcc/cp/parser.cc:14423 0x895239 cp_parser_selection_statement /root/source/gcc-12.2.0/gcc/cp/parser.cc:13186 0x86f5d5 cp_parser_statement /root/source/gcc-12.2.0/gcc/cp/parser.cc:12296 0x87016d cp_parser_statement_seq_opt /root/source/gcc-12.2.0/gcc/cp/parser.cc:12850 0x87021f cp_parser_compound_statement /root/source/gcc-12.2.0/gcc/cp/parser.cc:12802 0x88ec73 cp_parser_function_body /root/source/gcc-12.2.0/gcc/cp/parser.cc:25071 0x88ec73 cp_parser_ctor_initializer_opt_and_function_body /root/source/gcc-12.2.0/gcc/cp/parser.cc:25122 0x88fdbe cp_parser_function_definition_after_declarator /root/source/gcc-12.2.0/gcc/cp/parser.cc:31257 0x8900e3 cp_parser_late_parsing_for_member /root/source/gcc-12.2.0/gcc/cp/parser.cc:32189 0x86a06e cp_parser_class_specifier_1 /root/source/gcc-12.2.0/gcc/cp/parser.cc:26190 0x86af46 cp_parser_class_specifier /root/source/gcc-12.2.0/gcc/cp/parser.cc:26214
[Bug c++/108613] New: GCC12 internal compiler error on __int128_t in type_traits header
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108613
Bug ID: 108613
Summary: GCC12 internal compiler error on __int128_t in
type_traits header
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mserdarsanli at gmail dot com
Target Milestone: ---
https://godbolt.org/z/M1o34e6cx
Below code crashes GCC versions starting with GCC 12. It is only stuff from std
library headers, I've copied bits from preprocessed output.
template< class > struct remove_cv;
template< class _Tp> using __remove_cv_t = typename remove_cv< _Tp> ::type;
template< class _Tp, _Tp __v>
struct integral_constant {
static constexpr inline _Tp value = (__v);
typedef _Tp value_type;
typedef integral_constant type;
constexpr operator value_type() const noexcept { return value; }
constexpr value_type operator()() const noexcept { return value; }
};
using false_type = integral_constant< bool, false> ;
template< class ...> struct __or_;
template<> struct __or_< > : public false_type {};
template< class , class > struct is_same;
template< class _Tp, class ..._Types> using __is_one_of = __or_< is_same< _Tp,
_Types> ...> ;
template< class _Tp> using __is_signed_integer = __is_one_of< _Tp ,
signed char, signed short, signed int, signed long, signed long long,
signed __int128_t> ;
---
Stacktrace:
0xe2534f crash_signal
/root/source/gcc-12.2.0/gcc/toplev.cc:322
0x7c0535 grokdeclarator(cp_declarator const*, cp_decl_specifier_seq*,
decl_context, int, tree_node**)
/root/source/gcc-12.2.0/gcc/cp/decl.cc:12373
0x7c73fc groktypename(cp_decl_specifier_seq*, cp_declarator const*, bool)
/root/source/gcc-12.2.0/gcc/cp/decl.cc:5514
0x8797d5 cp_parser_type_id_1
/root/source/gcc-12.2.0/gcc/cp/parser.cc:24250
0x87c4f3 cp_parser_template_type_arg
/root/source/gcc-12.2.0/gcc/cp/parser.cc:24272
0x87c659 cp_parser_template_argument
/root/source/gcc-12.2.0/gcc/cp/parser.cc:18803
0x87c659 cp_parser_template_argument_list
/root/source/gcc-12.2.0/gcc/cp/parser.cc:18727
0x87c659 cp_parser_enclosed_template_argument_list
/root/source/gcc-12.2.0/gcc/cp/parser.cc:32059
0x87da7f cp_parser_template_id
/root/source/gcc-12.2.0/gcc/cp/parser.cc:18266
0x87e239 cp_parser_class_name
/root/source/gcc-12.2.0/gcc/cp/parser.cc:25713
0x875d8e cp_parser_qualifying_entity
/root/source/gcc-12.2.0/gcc/cp/parser.cc:7116
0x875d8e cp_parser_nested_name_specifier_opt
/root/source/gcc-12.2.0/gcc/cp/parser.cc:6798
0x88cf6c cp_parser_simple_type_specifier
/root/source/gcc-12.2.0/gcc/cp/parser.cc:19765
0x86aea5 cp_parser_type_specifier
/root/source/gcc-12.2.0/gcc/cp/parser.cc:19424
0x87b3d0 cp_parser_type_specifier_seq
/root/source/gcc-12.2.0/gcc/cp/parser.cc:24364
0x879744 cp_parser_type_id_1
/root/source/gcc-12.2.0/gcc/cp/parser.cc:24164
0x87c117 cp_parser_type_id
/root/source/gcc-12.2.0/gcc/cp/parser.cc:24260
0x87c117 cp_parser_alias_declaration
/root/source/gcc-12.2.0/gcc/cp/parser.cc:21778
0x897f37 cp_parser_template_declaration_after_parameters
/root/source/gcc-12.2.0/gcc/cp/parser.cc:31316
0x89827a cp_parser_explicit_template_declaration
/root/source/gcc-12.2.0/gcc/cp/parser.cc:31598
[Bug c++/108613] [12/13 Regression] GCC12 internal compiler error on __int128_t in type_traits header
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108613 --- Comment #6 from Serdar Sanli --- > Where did you get this from? The header uses signed __int128 > here, not signed __int128_t. Just checked and __GLIBCXX_TYPE_INT_N_0 is also __int128 for me. int128_t seem to come from somewhere else, in my case it is in cuda compiler generated code. Sorry for not being clear and wasting time, snippet I copied was only intended as a repro, not as a bug report on stdlibc++.
[Bug c++/119467] New: Missed optimization on wrapping builtin function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119467
Bug ID: 119467
Summary: Missed optimization on wrapping builtin function
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mserdarsanli at gmail dot com
Target Milestone: ---
Compiling below wrapper function
```
double powi(double a, int x)
{
return __builtin_powi(a, x);
}
```
generates assembly below:
```
powi(double, int):
sub rsp, 8
call__powidf2
add rsp, 8
ret
```
while if I replace calleee with any other function, it generates better code
with single jmp instruction:
```
extern double another_func(double a, int x);
double powi(double a, int x)
{
return another_func(a, x);
}
```
generates:
```
powi(double, int):
jmp another_func(double, int)
```
