vec macro into_boxed codegen regression #71861
Description
This is a regression from stable 1.42.0 to the latest beta & nightly
found because of this: https://internals.rust-lang.org/t/more-efficient-boxed-slice-creation/12271
pub fn bar2(n: usize) -> Box<[u32]> {
vec![0; n].into_boxed_slice()
}I think the regression happened because of a missed optimization to inline alloc::raw_vec::RawVec<T,A>::allocate_in::{{closure}}, so it generates unnecessary panic handlers
alloc::raw_vec::RawVec<T,A>::allocate_in::{{closure}}:
push rax
call qword ptr [rip + alloc::raw_vec::capacity_overflow@GOTPCREL]
ud2
example::bar2:
push r14
push rbx
push rax
mov ecx, 4
mov rax, rdi
mul rcx
jo .LBB1_5
mov rbx, rdi
mov r14, rax
test rax, rax
je .LBB1_4
mov esi, 4
mov rdi, r14
call qword ptr [rip + __rust_alloc_zeroed@GOTPCREL]
test rax, rax
je .LBB1_6
mov rcx, rax
.LBB1_4:
mov rax, rcx
mov rdx, rbx
add rsp, 8
pop rbx
pop r14
ret
.LBB1_5:
call alloc::raw_vec::RawVec<T,A>::allocate_in::{{closure}}
ud2
.LBB1_6:
mov esi, 4
mov rdi, r14
call qword ptr [rip + alloc::alloc::handle_alloc_error@GOTPCREL]
ud2core::ptr::drop_in_place:
mov rsi, qword ptr [rdi + 8]
test rsi, rsi
je .LBB0_2
shl rsi, 2
test rsi, rsi
je .LBB0_2
mov rdi, qword ptr [rdi]
mov edx, 4
jmp qword ptr [rip + __rust_dealloc@GOTPCREL]
.LBB0_2:
ret
alloc::raw_vec::RawVec<T,A>::allocate_in::{{closure}}:
push rax
call qword ptr [rip + alloc::raw_vec::capacity_overflow@GOTPCREL]
ud2
alloc::raw_vec::RawVec<T,A>::allocate_in::{{closure}}:
push rax
mov rax, qword ptr [rdi]
mov rsi, qword ptr [rdi + 8]
mov rdi, rax
call qword ptr [rip + alloc::alloc::handle_alloc_error@GOTPCREL]
ud2
example::bar2:
push r15
push r14
push rbx
sub rsp, 32
mov ecx, 4
xor esi, esi
mov rax, rdi
mul rcx
mov rbx, rax
setno al
jo .LBB3_18
mov r14, rdi
mov sil, al
shl rsi, 2
mov qword ptr [rsp + 8], rbx
mov qword ptr [rsp + 16], rsi
test rbx, rbx
je .LBB3_3
mov rdi, rbx
call qword ptr [rip + __rust_alloc_zeroed@GOTPCREL]
mov rsi, rax
.LBB3_3:
test rsi, rsi
je .LBB3_19
mov rax, rbx
shr rax, 2
mov qword ptr [rsp + 8], rsi
mov qword ptr [rsp + 16], rax
mov qword ptr [rsp + 24], r14
cmp rax, r14
je .LBB3_15
jb .LBB3_10
test rbx, rbx
je .LBB3_15
lea r15, [4*r14]
cmp rbx, r15
je .LBB3_14
mov edx, 4
mov rdi, rsi
mov rsi, rbx
test r15, r15
je .LBB3_9
mov rcx, r15
call qword ptr [rip + __rust_realloc@GOTPCREL]
test rax, rax
je .LBB3_16
mov rsi, rax
mov rbx, r15
jmp .LBB3_14
.LBB3_9:
call qword ptr [rip + __rust_dealloc@GOTPCREL]
xor ebx, ebx
mov esi, 4
.LBB3_14:
mov qword ptr [rsp + 8], rsi
shr rbx, 2
mov qword ptr [rsp + 16], rbx
.LBB3_15:
mov rax, rsi
mov rdx, r14
add rsp, 32
pop rbx
pop r14
pop r15
ret
.LBB3_18:
call alloc::raw_vec::RawVec<T,A>::allocate_in::{{closure}}
ud2
.LBB3_19:
lea rdi, [rsp + 8]
call alloc::raw_vec::RawVec<T,A>::allocate_in::{{closure}}
ud2
.LBB3_10:
lea rdi, [rip + .L__unnamed_1]
lea rdx, [rip + .L__unnamed_2]
mov esi, 36
call qword ptr [rip + core::panicking::panic@GOTPCREL]
ud2
.LBB3_16:
mov esi, 4
mov rdi, r15
call qword ptr [rip + alloc::alloc::handle_alloc_error@GOTPCREL]
ud2
mov rbx, rax
lea rdi, [rsp + 8]
call core::ptr::drop_in_place
mov rdi, rbx
call _Unwind_Resume@PLT
ud2
.L__unnamed_1:
.ascii "Tried to shrink to a larger capacity"
.L__unnamed_3:
.ascii "/rustc/f05a5240440b3eaef1684a7965860fab40301947/src/libcore/macros/mod.rs"
.L__unnamed_2:
.quad .L__unnamed_3
.asciz "I\000\000\000\000\000\000\000\n\000\000\000\t\000\000"