[libc++] Avoid non-trivial assignment in `__uninitialized_allocator_copy_impl`
__uninitialized_allocator_copy_impl has an optimization that replaces allocator_traits::construct with std::copy for raw pointer ranges when the element type is trivially copy constructible and trivially copy assignable.
The copy-assignment trait only checks whether assignment from const T& is trivial. That is weaker than the expression used by std::copy, which evaluates *out = *in. If overload resolution selects a different non-trivial assignment operator for that expression, std::copy can call that operator on uninitialized storage.
Const-qualify the input pointers in the optimized overload instead. This makes the std::copy expression assign from const T&, matching the existing is_trivially_copy_assignable check, preserving the optimized path when that assignment is trivial, and falling back to placement construction otherwise.
Add a vector copy-constructor regression test with a type whose defaulted copy assignment is trivial but whose templated assignment operator is selected for non-const lvalue sources.
Tested with:
build/bin/llvm-lit -q build/runtimes/runtimes-bins/libcxx/test --filter='(vector.cons/copy.pass|uninitialized_allocator_copy\\.pass)'
build/bin/llvm-lit -q build/runtimes/runtimes-bins/libcxx/test --param std=c++20 --filter='vector.cons/copy.pass'
build/bin/llvm-lit -q build/runtimes/runtimes-bins/libcxx/test --param std=c++11 --filter='vector.cons/copy.pass'
[libc++] Avoid non-trivial assignment in `__uninitialized_allocator_copy_impl`
__uninitialized_allocator_copy_impl has an optimization that replaces allocator_traits::construct with std::copy for raw pointer ranges when the element type is trivially copy constructible and trivially copy assignable.
The copy-assignment trait only checks whether assignment from const T& is trivial. That is weaker than the expression used by std::copy, which evaluates *out = *in. If overload resolution selects a different non-trivial assignment operator for that expression, std::copy can call that operator on uninitialized storage.
Const-qualify the input pointers in the optimized overload instead. This makes the std::copy expression assign from const T&, matching the existing is_trivially_copy_assignable check, preserving the optimized path when that assignment is trivial, and falling back to placement construction otherwise.
Add a regression test with a type whose defaulted copy assignment is trivial but whose templated assignment operator is selected for non-const lvalue sources.
Tested with:
build/bin/llvm-lit -q build/runtimes/runtimes-bins/libcxx/test --filter='uninitialized_allocator_copy(\\.pass|_template_op_assign)'
[RFC][NFCI][Constants] Add `Constant::isZeroValue`
The old `isZeroValue` was removed because it was functionally identical to
`Constant::isNullValue`. Currently, a "null value" in LLVM means a zero value.
We are moving toward changing the semantics of `ConstantPointerNull` to
represent a semantic null pointer instead of a zero-valued pointer. As a result,
the meaning of "null value" will also change in the future.
This PR series is the first step toward renaming the two widely used "null
value" interfaces to "zero value". As the first PR in the series, this change
adds a "new" `isZeroValue` alongside `isNullValue`, and makes `isNullValue` call
`isZeroValue` directly. Then, all uses of `isNullValue` in LLVM are replaced
with `isZeroValue`. Uses in other projects will be updated in separate PRs.
The plan is to eventually remove `isNullValue` after all uses have been
migrated.
[AMDGPU] Add `.amdgpu.info` section for per-function metadata
AMDGPU object linking requires the linker to propagate resource usage
(registers, stack, LDS) across translation units. To support this, the compiler
must emit per-function metadata and call graph edges in the relocatable object
so the linker can compute whole-program resource requirements.
This PR introduces a `.amdgpu.info` ELF section using a tagged, length-prefixed
binary format: each entry is encoded as:
```
[kind: u8] [len: u8] [payload: <len> bytes]
```
A function scope is opened by an `INFO_FUNC` entry (containing a symbol
reference), followed by per-function attributes (register counts, flags, private
segment size) and relational edges (direct calls, LDS uses, indirect call
signatures). String data such as function type signatures is stored in a
companion `.amdgpu.strtab` section.
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[AMDGPU] Add VOP1 DPP8 pseudo infrastructure
Add VOP_DPP8_Pseudo/VOP1_DPP8_Pseudo classes for DPP8 instructions, similar to
the existing VOP_DPP_Pseudo/VOP1_DPP_Pseudo pattern.
[VPlan] Lift isUsedByLoadStoreAddr into vputils, operate on VPValue(NFC) (#196415)
Extract the helper previously scoped to VPReplicateRecipe::computeCost
and make it available from VPlanUtils so other transforms can query
whether a VPValue is used as part of another load or store's address.
Also relax the input type from VPUser * to VPValue *: the worklist now
tracks VPValues directly, and traversal is gated on the user being a
VPSingleDefRecipe before walking its own users. This is NFC for the
existing caller.
