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* [gcc r13-4371] libstdc++: Fix src/c++17/memory_resource for H8 targets [PR107801]
@ 2022-11-28 16:57 Jonathan Wakely
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From: Jonathan Wakely @ 2022-11-28 16:57 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:75e562d2c4303d3918be9d1563284b0c580c5e45
commit r13-4371-g75e562d2c4303d3918be9d1563284b0c580c5e45
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon Nov 28 13:28:53 2022 +0000
libstdc++: Fix src/c++17/memory_resource for H8 targets [PR107801]
This fixes compilation failures for H8 multilibs. For the normal
multilib (ILP16L32?), the chunk struct does not have the expected size,
because uint32_t is type long and has alignment 4 (by default). This
forces sizeof(chunk) to be 12 instead of the expected 10. We can fix
that by using bitset::size_type instead of uint32_t, so that we only use
a 16-bit size when size_t and pointers are 16-bit types.
For the I32LP16 multilibs that use -mint32 int is wider than size_t
and so arithmetic expressions involving size_t promote to int. This
means we need some explicit casts back to size_t.
libstdc++-v3/ChangeLog:
PR libstdc++/107801
* src/c++17/memory_resource.cc (chunk::_M_bytes): Change type
from uint32_t to bitset::size_type. Adjust static assertion.
(__pool_resource::_Pool::replenish): Cast to size_t after
multiplication instead of before.
(__pool_resource::_M_alloc_pools): Ensure both arguments to
std::max have type size_t.
Diff:
---
libstdc++-v3/src/c++17/memory_resource.cc | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/libstdc++-v3/src/c++17/memory_resource.cc b/libstdc++-v3/src/c++17/memory_resource.cc
index 0bd94dbc6a7..a1854c55bd0 100644
--- a/libstdc++-v3/src/c++17/memory_resource.cc
+++ b/libstdc++-v3/src/c++17/memory_resource.cc
@@ -505,7 +505,7 @@ namespace pmr
}
// Allocated size of chunk:
- uint32_t _M_bytes = 0;
+ bitset::size_type _M_bytes = 0;
// Start of allocated chunk:
std::byte* _M_p = nullptr;
@@ -579,7 +579,7 @@ namespace pmr
// For 16-bit pointers it's five pointers (10 bytes).
// TODO pad 64-bit to 4*sizeof(void*) to avoid splitting across cache lines?
static_assert(sizeof(chunk)
- == sizeof(bitset::size_type) + sizeof(uint32_t) + 2 * sizeof(void*));
+ == 2 * sizeof(bitset::size_type) + 2 * sizeof(void*));
// An oversized allocation that doesn't fit in a pool.
struct big_block
@@ -734,7 +734,7 @@ namespace pmr
_M_blocks_per_chunk = std::min({
max_blocks,
__opts.max_blocks_per_chunk,
- (size_t)_M_blocks_per_chunk * 2
+ size_t(_M_blocks_per_chunk * 2)
});
}
}
@@ -1057,7 +1057,8 @@ namespace pmr
// Decide on initial number of blocks per chunk.
// At least 16 blocks per chunk seems reasonable,
// more for smaller blocks:
- size_t blocks_per_chunk = std::max(size_t(16), 1024 / block_size);
+ size_t blocks_per_chunk = 1024 / block_size;
+ blocks_per_chunk = std::max(size_t(16), blocks_per_chunk);
// But don't exceed the requested max_blocks_per_chunk:
blocks_per_chunk
= std::min(blocks_per_chunk, _M_opts.max_blocks_per_chunk);
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