https://github.com/llvmbot created
https://github.com/llvm/llvm-project/pull/95264
Backport 382f70a877f0 d129ea8d2fa3
Requested by: @DimitryAndric
>From bc2f4cbcc3e734c0ae847964f0c7f1912e770e16 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionn...@gmail.com>
Date: Wed, 24 Jan 2024 09:28:58 -0500
Subject: [PATCH 1/2] [libc++][NFC] Rewrite function call on two lines for
clarity (#79141)
Previously, there was a ternary conditional with a less-than comparison
appearing inside a template argument, which was really confusing because
of the <...> of the function template. This patch rewrites the same
statement on two lines for clarity.
(cherry picked from commit 382f70a877f00ab71f3cb5ba461b52e1b59cd292)
---
libcxx/include/string | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/libcxx/include/string b/libcxx/include/string
index ba169c3dbfc9e..618ceb71b26b4 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -1943,8 +1943,8 @@ private:
if (__s < __min_cap) {
return static_cast<size_type>(__min_cap) - 1;
}
- size_type __guess =
- __align_it < sizeof(value_type) < __alignment ? __alignment /
sizeof(value_type) : 1 > (__s + 1) - 1;
+ const size_type __boundary = sizeof(value_type) < __alignment ?
__alignment / sizeof(value_type) : 1;
+ size_type __guess = __align_it<__boundary>(__s + 1) - 1;
if (__guess == __min_cap)
++__guess;
return __guess;
>From e803d6ad5a06fadd9755f4afe058acd69dd11089 Mon Sep 17 00:00:00 2001
From: Vitaly Buka <vitalyb...@google.com>
Date: Thu, 2 May 2024 14:26:38 -0700
Subject: [PATCH 2/2] [libcxx] Align `__recommend() + 1` by __endian_factor
(#90292)
This is detected by asan after #83774
Allocation size will be divided by `__endian_factor` before storing. If
it's not aligned,
we will not be able to recover allocation size to pass into
`__alloc_traits::deallocate`.
we have code like this
```
auto __allocation = std::__allocate_at_least(__alloc(), __recommend(__sz) + 1);
__p = __allocation.ptr;
__set_long_cap(__allocation.count);
void __set_long_cap(size_type __s) _NOEXCEPT {
__r_.first().__l.__cap_ = __s / __endian_factor;
__r_.first().__l.__is_long_ = true;
}
size_type __get_long_cap() const _NOEXCEPT {
return __r_.first().__l.__cap_ * __endian_factor;
}
inline ~basic_string() {
__annotate_delete();
if (__is_long())
__alloc_traits::deallocate(__alloc(), __get_long_pointer(),
__get_long_cap());
}
```
1. __recommend() -> even size
2. `std::__allocate_at_least(__alloc(), __recommend(__sz) + 1)` - > not
even size
3. ` __set_long_cap() `- > lose one bit of size for __endian_factor == 2
(see `/ __endian_factor`)
4. `__alloc_traits::deallocate(__alloc(), __get_long_pointer(),
__get_long_cap())` -> uses even size (see `__get_long_cap`)
(cherry picked from commit d129ea8d2fa347e63deec0791faf389b84f20ce1)
---
libcxx/include/string | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/libcxx/include/string b/libcxx/include/string
index 618ceb71b26b4..56e2ef09947f4 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -1943,10 +1943,10 @@ private:
if (__s < __min_cap) {
return static_cast<size_type>(__min_cap) - 1;
}
- const size_type __boundary = sizeof(value_type) < __alignment ?
__alignment / sizeof(value_type) : 1;
+ const size_type __boundary = sizeof(value_type) < __alignment ?
__alignment / sizeof(value_type) : __endian_factor;
size_type __guess = __align_it<__boundary>(__s + 1) - 1;
if (__guess == __min_cap)
- ++__guess;
+ __guess += __endian_factor;
return __guess;
}
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