https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127674
Bug ID: 127674
Summary: new[]/delete[] pair kept when we use
__builtin_assume_aligned
Product: gcc
Version: 16.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: saicharan at astrome dot co
Target Milestone: ---
The unused new[]/delete[] pair is not eliminated at -O3 when the pointer
is passed through __builtin_assume_aligned.
void f() {
unsigned char *p = new unsigned char[23];
p = static_cast<unsigned char *>(__builtin_assume_aligned(p, 8));
delete[] p;
}
Assembly generated for x86-64:
"f()":
sub rsp, 8
mov edi, 23
call "operator new[](unsigned long)"
add rsp, 8
mov rdi, rax
jmp "operator delete[](void*)"
Removing the __builtin_assume_aligned line eliminates the redundant pair.
Compiler Explorer link: https://godbolt.org/z/K78ovdYrr
