On 18/12/23 09:36 +0100, Martin Küttler wrote:
This is a small change to libstdc++ which does not change any behavior.
Please CC the libstd...@gcc.gnu.org list on all libstdc++ patches, as
documented at https://gcc.gnu.org/lists.html
Otherwise I won't see the patches unless I happen to glance at the
gcc-patches archive by chance.
This change has two, ihmo positive, implications:
- The implicit conversion from double to int is avoided (Avoiding a
warning).
I don't see any warning here. What do you see?
- No floating point number is used at all, which could be significant
in some scenarios.
Yes, it seems worth doing for this reason. I'll test+push the patch,
thanks.
Looking at path::_List::reserve now, we probably also want to avoid
overflow. Although a path with INT_MAX/1.5 components seems
implausible for 32-bit and 64-bit targets, it could be a problem for
16-bit targets. I'll take care of that too.
------------
diff --git a/libstdc++-v3/src/c++17/fs_path.cc
b/libstdc++-v3/src/c++17/fs_path.cc
index d65b5482e8b..b47ed0aa7aa 100644
--- a/libstdc++-v3/src/c++17/fs_path.cc
+++ b/libstdc++-v3/src/c++17/fs_path.cc
@@ -447,8 +447,9 @@ path::_List::reserve(int newcap, bool exact = false)
if (curcap < newcap)
{
- if (!exact && newcap < int(1.5 * curcap))
- newcap = 1.5 * curcap;
+ const int nextcap = curcap + curcap / 2;
+ if (!exact && newcap < nextcap)
+ newcap = nextcap;
void* p = ::operator new(sizeof(_Impl) + newcap * sizeof(value_type));
std::unique_ptr<_Impl, _Impl_deleter> newptr(::new(p) _Impl{newcap});
