[lld][ELF] filter out section symbols when use BP reorder (#151685)
When using Temporal Profiling with the BP algorithm, we encounter an
issue with the internal function reorder. In cases where the symbol
table contains entries like:
```
Symbol table '.symtab' contains 45 entries:
Num: Value Size Type Bind Vis Ndx Name
10: 0000000000000000 0 SECTION LOCAL DEFAULT 18 .text.L1
11: 0000000000000000 24 FUNC LOCAL DEFAULT 18 L1
````
The zero-sized section symbol .text.L1 gets stored in the secToSym map
first. However, when the function lookup searches for L1 (as seen in
[BPSectionOrdererBase.inc:191](https://github.com/llvm/llvm-project/blob/main/lld/include/lld/Common/BPSectionOrdererBase.inc#L191)),
it fails to find the correct entry in rootSymbolToSectionIdxs because
the section symbol has already claimed that slot.
This patch fixes the issue by skipping zero-sized symbols during the
addSections process, ensuring that function symbols are properly
registered for lookup.
MC: Refine ALIGN relocation conditions
Each section now tracks the index of the first linker-relaxable
fragment, enabling two changes:
* Delete redundant ALIGN relocations before the first linker-relaxable
instruction in a section. The primary example is the offset 0
R_RISCV_ALIGN relocation for a text section aligned by 4.
* For alignments larger than the NOP size after the first
linker-relaxable instruction, ALIGN relocations are now generated, even in
norelax regions. This fixes the issue #150159.
The new test llvm/test/MC/RISCV/Relocations/align-after-relax.s
verifies the required ALIGN in a norelax region following
linker-relaxable instructions.
By using a fragment index within the subsection (which is less than or
equal to the section's index), the implementation may generate redundant
ALIGN relocations in lower-numbered subsections before the first
linker-relaxable instruction.
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[DA] Fix the check between Subscript and Size after delinearization (#151326)
Delinearization provides two values: the size of the array, and the
subscript of the access. DA checks their validity (`0 <= subscript <
size`), with some special handling. In particular, to ensure `subscript
< size`, calculate the maximum value of `subscript - size` and check if
it is negative. There was an issue in its process: when `subscript -
size` is expressed as an affine format like `init + step * i`, the value
in the last iteration (`start + step * (num_iterations - 1)`) was
assumed to be the maximum value. This assumption is incorrect in the
following cases:
- When `step` is negative
- When the AddRec wraps
This patch introduces extra checks to ensure the sign of `step` and
verify the existence of nsw/nuw flags.
Also, `isKnownNonNegative(S - smax(1, Size))` was used as a regular
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vfs: Add support for file cloning to VOP_COPY_FILE_RANGE
NFSv4 has a separate CLONE operation from COPY with
a couple of semantics differences. Unlike COPY, CLONE
must complete the "copy on write" and cannot return
partially copied. It also is required to use offsets (and
the length if not to EOF) that are aligned to a buffer
boundary.
Since VOP_COPY_FILE_RANGE() can already do "copy on write"
for file systems that support it, such as ZFS with block
cloning enabled, all this patch does is add a flag called
COPY_FILE_RANGE_CLONE so that it will conform to the
rule that it must do a "copy on write" to completion.
The patch also adds a new pathconf(2) name _PC_CLONE_BLKSIZE,
which acquires the blocksize requirement for cloning and
returns 0 for file systems that do not support the
"copy on write" feature. (This is needed for the NFSv4.2
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15.0: Update main to -PRERELEASE
This marks the start of the FreeBSD 15.0 release cycle; the tree is now
in "code slush".
Developers are encouraged to prioritize fixing bugs over adding new
featuresa t this time. Commit approval from re@ is not required but
if new features introduce problems they may be removed from the
upcoming release.
Approved by: re (implicit)
