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cgen: minimise sizeof(EmptyStruct) to 0 for gcc/clang and to 1 for tcc/msvc, by changing EMPTY_STRUCT_DECLARATION and EMPTY_STRUCT_INITIALIZATION (#16733)

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This commit is contained in:
Delyan Angelov
2022-12-22 21:47:39 +02:00
committed by GitHub
parent e01dac885c
commit fc5826b7ca
9 changed files with 135 additions and 34 deletions
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18
vlib/builtin/array.v
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@@ -47,9 +47,13 @@ fn __new_array_with_default(mylen int, cap int, elm_size int, val voidptr) array
len: mylen
cap: cap_
}
// x := []EmptyStruct{cap:5} ; for clang/gcc with -gc none,
// -> sizeof(EmptyStruct) == 0 -> elm_size == 0
// -> total_size == 0 -> malloc(0) -> panic;
// to avoid it, just allocate a single byte
total_size := u64(cap_) * u64(elm_size)
if cap_ > 0 && mylen == 0 {
arr.data = unsafe { malloc(total_size) }
arr.data = unsafe { malloc(__at_least_one(total_size)) }
} else {
arr.data = vcalloc(total_size)
}
@@ -78,7 +82,7 @@ fn __new_array_with_array_default(mylen int, cap int, elm_size int, val array, d
cap_ := if cap < mylen { mylen } else { cap }
mut arr := array{
element_size: elm_size
data: unsafe { malloc(u64(cap_) * u64(elm_size)) }
data: unsafe { malloc(__at_least_one(u64(cap_) * u64(elm_size))) }
len: mylen
cap: cap_
}
@@ -99,7 +103,7 @@ fn __new_array_with_map_default(mylen int, cap int, elm_size int, val map) array
cap_ := if cap < mylen { mylen } else { cap }
mut arr := array{
element_size: elm_size
data: unsafe { malloc(u64(cap_) * u64(elm_size)) }
data: unsafe { malloc(__at_least_one(u64(cap_) * u64(elm_size))) }
len: mylen
cap: cap_
}
@@ -156,7 +160,7 @@ fn (mut a array) ensure_cap(required int) {
cap *= 2
}
new_size := u64(cap) * u64(a.element_size)
new_data := unsafe { malloc(new_size) }
new_data := unsafe { malloc(__at_least_one(new_size)) }
if a.data != unsafe { nil } {
unsafe { vmemcpy(new_data, a.data, u64(a.len) * u64(a.element_size)) }
// TODO: the old data may be leaked when no GC is used (ref-counting?)
@@ -601,13 +605,9 @@ pub fn (a &array) clone() array {
// recursively clone given array - `unsafe` when called directly because depth is not checked
[unsafe]
pub fn (a &array) clone_to_depth(depth int) array {
mut size := u64(a.cap) * u64(a.element_size)
if size == 0 {
size++
}
mut arr := array{
element_size: a.element_size
data: vcalloc(size)
data: vcalloc(u64(a.cap) * u64(a.element_size))
len: a.len
cap: a.cap
}